WO2002025945A1 - Method for transmitting and displaying image information - Google Patents

Abstract

The invention relates to a method, transmitter equipment and receiver equipment for transmitting image information. Two or more image levels (1, 2, 3) are simultaneously transmitted to a receiver, and the user can produce desired image combinations (8) onto a display by selecting a specific image level or levels to be visible and leaving a remaining level or levels invisible. In other words, an image information transmission (25) to be transmitted, such as a multiplex in a digital television system (20) or a WWW page, is composed of two or more image levels to be transferred simultaneously and belonging to the same program or WWW page. The user may compile a customized service on the receiver display by selecting the desired image levels, i.e. transparent films, for use.

Description

METHOD FOR TRANSMITTING AND DISPLAYING IMAGE INFORMATION

BACKGROUND OF THE INVENTION

[0001] The invention relates generally to methods for transmitting information to a receiver in a transmission system and for displaying the information on the receiver display.

[0002] The Internet refers generally to interconnected networks supporting TCP/IP-based (Transport Control Protocol/Internet Protocol) applications, such as the World Wide Web (WWW), SMTP (Simple Message Transport Protocol), e-mail or FTP (File Transfer Protocol). The different parts of the Internet are often referred to as sub-networks, and they are interconnected by gateways or routers. Computers connected to the network are called hosts. One host computer is often a client, while another is a server. A client is a computer which requests for services or receives them from another computer in the network. A server is a computer providing services for other computers in the network.

[0003] The main reason for the explosion in the use of the Internet has been the WWW which allows text, graphics, audio information and video information to be arranged in a desired manner into a document located in the net. The result is a multimedia package for which a desired layout can be designed. In addition, a WWW page may include hyperlinks to other pages, whereby large web sites can be set up with easy transfer from one page to another. The content and layout of a WWW page is determined using what is known as a mark-up language. A commonly used mark-up language is HTML (Hyper Text Mark-up Language), although today the XML (Extended Mark-up Language) and the WML (Wireless Mark-up Language), which are better suited particularly for the display capacity of wireless terminals, are gaining ground. The mark-up language is used for determining the content of the WWW page and how the user's browser is to show the content on the client display. When the user wishes to view a particular WWW page, he uses the browser to command the page (document) in question to be retrieved. The page, which may be an HTML file stored on the same computer or on a local area network server, is opened by the browser (such as the Netscape Navigator or Microsoft Explorer) and shown on the display. However, the requested document often resides on a server connected to the Internet to which the browser sends the request for the page. In that case, an HTML code is loaded from the server to the client computer and the browser displays the document to the user according to the HTML specifications.

[0004] New digital broadcast networks have been developed in different parts of the world for transmitting radio and television broadcasts. These networks include the digital radio network DAB (Digital Audio Broadcasting) and the digital television network DVB (Digital Video Broadcasting). The DVB system employs MPEG (Moving Picture Expert Group) standards for source-coding and multiplexing audio visual signals. Television programs are technically composed of three elements: audio and video information and additional information supporting these. In the DVB system each one of these signals is arranged into a separate packet to form a corresponding packet stream referred to as a Packetized Elementary Stream (PES). A single television broadcast thus comprises an audio-PES, video-PES and an additional information-PES. These elementary streams (PES) are multiplexed to provide a standard data stream, or a Transport Stream (TS). The transport stream TS, called a multiplex, may contain elementary streams related to a plural number of programs. Each TS packet contains a four-bit header comprising a packet identification code (PID). Packets belonging to one and the same service carry the same PID. The header data further comprises a sequence number to ensure that the packets will be decoded in the correct order. In addition, the TS header field is used for transferring PID values into Service Information SI tables. The determining of PID values for SI data has been specified in the ETS 300 468 [7]. The PES packets making up the data load to be transferred in the TS transfer stream packets comprise a PES header field, which always comes after the TS header field. The PES header field carries a presentation time stamp (PST) which is used to achieve audio/video synchronization. To synchronize data associated with a program, a decode time stamp (DTS) may be added to the header field. Audio, video and data PES packets relating to the same program 1 are multiplexed using a program map table (PMT). The PMT is a TS packet the load of which consists of the PIDs of each packetized elementary stream PES of program 1. In addition to the identification code, the header field of the PES packet comprises a stream_type. StreamJD and streamjype values are set according to Table 2-18 and Table 229 of the ISO/IEC13818-1. Program 2 is multiplexed according to a separate PMT, etc. The separate programs are in turn multiplexed by applying a program association table (PAT) to form the TS. The data load of the PAT (which is also a TS packet) consists of PIDs for each PMT. The receiver always finds the PAT using PID=0 which always opens the entire program transfer structure of the TS. Together with a NIT, i.e. a Network Information Table, the PAT and the PMT form Program Specific Information (PSI) which contains the information about the content of the TS in question. In addition, the DVB specifies the service information SI included in the TS multiplex, the service information complementing the program-specific service information PSI by providing data which assists in the automated tuning of the receiver and in specifying the service type, and additional data to be displayed to the user. According to the DVB standard, a PID 0x0011 is further used for transmitting a Service Description Table SDT, for example, and a PID 0x0012 for transmitting an Event Information Table (EIT). The SI bit stream of the SDT lists all the TS services from the TS in question. The SDT is described in a descriptor of the SDT in which all the services and the related descriptors are listed with reference to the ID of the TS. These descriptors (service descriptions) allow additional information to be obtained from individual packetized elementary streams. The descriptions are added to the service identification service_id of each service. The SI data, which forms part of the DVB bit streams, provides the user with information assisting the user in the selection of services and/or events. An event relates to grouped elementary broadcast streams which begin and end at a predefined time and which belong to a common service, such as a first half of a football match, or a commercial. The receiver may configure itself automatically to a selected service. The SI information comprises for example an SDT (Service Description Table) which contains the names of the services and their producers, for example, and an Event Information Table EIT which comprises information relating to events or programs, such as duration, starting time, or the name of an event. Lately digital television has also been associated with an Electronic Program Guide EPG which may be based on specific data belonging to the SI field. The DVB system also comprises teletext. Teletext data is conveyed in the above PES packets, which are in turn transferred in TS packets. The PSI information of a particular service provides the packet ID of the teletext stream associated with the service. The DVB system can also be used for transmitting graphic objects, such as subtitles, for display on the television display. Sub-titling information is transmitted as a separate PES.

[0005] A characteristic of these prior art image transmission and display methods is that they provide the same image information to all users. Internet allows more individual services or services directed to smaller groups to be offered by guiding the users to different WWW pages. Digital television systems allow different program packets to be produced for different user groups, but this consumes the transmission capacity of the system.

SUMMARY OF THE INVENTION

[0006] It is an object of the invention to provide an improved transmission and display method for presenting image information directed to different user groups or users. [0007] This and other objects and advantages of the invention are achieved with a method according to claim 1 , receiver equipment according to claims 22 and 23, transmitter equipment according to claim 29 and a metalanguage document according to claim 33.

[0008] According to an underlying idea of the invention, two or more image levels are transmitted simultaneously from the transmitting end to the receiving end, the user being allowed to selectively choose or combine desired image entities to be displayed by selecting a particular image level or levels for display and by leaving the remaining image level or levels invisible. In other words, an image information item to be transmitted, such as a multiplex or a WWW page in a digital television system, consists of two or more image levels which belong to the same program or WWW page and are to be transmitted simultaneously. The user may compile his own service onto the display by selecting the desired image levels, i.e. transparent films, for use. In a first preferred embodiment, most of the image information to be transmitted may be shared by all the users, additional image levels being used for transmitting additional information simultaneously and the user being able to activate the additional information to be visible on top of the common image information. Since the amount of transmission capacity needed for transmitting the additional image levels accounts for a relatively small portion of the capacity needed for transmitting the final combination (most of the capacity being needed for the broadcast), the invention allows individual services to be provided to the users at significantly lower transmission capacities than in prior art methods, where a separate WWW page or television program would have had to be transferred for each individual combination. [0009] The invention can be used for example in interactive network games where the background image of a game is broadcast to all the users, whereas player-specific image information is transmitted on separate image levels. A feedback conversation or the copy or images of a commercial relating to a TV program can also be transmitted on separate image levels such that the user may select to display them or remove them from the display as desired.

[0010] Image levels can be attached to other image information transmitted in the transmission system in various ways. When graphics and video signals are concerned, separate colour codes may be used for different image levels. In other words, a specific colour or colour code is associated with a specific image level and is only displayed if the level concerned has been activated by the user.

[0011] Another alternative suitable for use in connection with a DVB multiplex, for example, is to use a data stream associated with the primary image information for transmitting additional image levels. The image levels are preferably separated from one another at the application level in the receiver, in which case the transmission system does not need to support the image level transmission of the invention. This allows the content producer to freely modify his services based on image levels, and they are available to the user provided that he has an application (equipment, for example) supporting the service. In a digital television system, such as the DVB, the data stream may be transmitted as a data transmission service which is guided to the corresponding application. It is also possible to transmit additional image level information in a data transmission service in which a separate sub-data flow is determined for each image level. The image levels can be separated from one another in the receiver by using tags added to the specifications (such as the SDT in the DVB) defined using a metalanguage describing the services of the transmission system. In that case the receiver is arranged to separate the sub- data streams on the basis of the meta language describing the services of the transmission system and to show the data corresponding to the image level selected by the user.

[0012] In an embodiment of the invention, the WWW page to be transmitted to the user includes information relating to a plural number of image levels, the browser displaying to the user only the image levels that are defined in the document as levels to be displayed. The user may also selectively open and hide different image levels and thereby flexibly change the content of the display without having to wait for a new page to be loaded from the server each time when he wishes to change the content of the page. This speeds up the browsing of the information. The user may also combine image levels to produce a desired combined version of the page. This allows a single WWW page loaded from the server to be used for producing different versions suitable for different users and user groups. The different image levels can be added to the WWW page for example by incorporating a new tag, a level tag, into the mark-up language used. Information associated with a specific level is placed between the level tags corresponding to the level in question. For example, an HTML file may contain five image levels comprising different kinds of text for display on the same location on the display. The browser displays the HTML document according to the image level specifications selected by the user. Another alternative for implementing image levels in a meta-language document (such as the HTML) is to use different colour codes for different image levels.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In the following, the invention will be described in connection with preferred embodiments and with reference to the accompanying drawings, in which Figure 1 illustrates the compiling of an image consisting of image levels onto a display in accordance with the invention;

Figure 2 illustrates the transmission of image levels from the content provider through a DVB transmission network to a receiver and the compiling of an image to be displayed at the receiver in accordance with the invention;

Figure 3 illustrates an example of the contents of a background image and image levels and a compiled image;

Figure 4 illustrates an interactive hybrid system in which the image information is sent to the receiver through a DVB system and the receiver is provided with an Internet return channel to the server of the content provider;

Figures 5A and 5B are flow diagrams illustrating the implementation of a game based on network levels of the invention in the interactive system of

Figure 4;

Figure 6 is a block diagram of a DVB receiver of the invention; Figure 7 illustrates a page map; and Figure 8 illustrates a visibility control menu.

PREFERRED EMBODIMENTS OF THE INVENTION

[0014] The present invention can be applied in different kinds of transmission systems in which information is transferred to a receiver for display. In the following, the invention is described with reference to examples in which image information is transferred between a WWW server and a client browser and transmitted through a digital video broadcast (DVB) system to a receiver.

[0015] The basic principle of the present invention is illustrated in Figure 1. The image information to be displayed consists of two or more image levels. In the example of Figure 1 there are three image levels: a background image 1, image level 1 and image level. The content of the background image is illustrated with a rectangle 1 , the content of image level 1 with an ellipsis 2 and the content of image level 2 with a triangle 3. The background image, image level 1 and image level 2 are supplied to visibility controllers 4, 5 and image level 3 to controller 6. Controllers 4, 5 and 6 control the visibility of each image level on the display according to visibility control 9 provided by the user. The simplest visibility control is an ON/OFF-type control where the image level is set to be either visible or invisible. Another possible control is one in which visibility is adjusted step by step or steplessly between visibility and invisibility. When a background image is concerned, it is also possible to adjust the degree of transparency, i.e. to what extent the image underneath (such as a TV program) is visible through the background image and image levels 2 and 3. In the example of Figure 1 , the controller 4 sets the background image and image level 2 to be completely visible, whereas image level 1 is set to be invisible. The transparency value of the background image can also determine the absolute visibility level of the 100% visibility of other image levels. The image information is supplied from the controllers 4, 5 and 6 to a combiner 7 which combines the image levels according to the settings provided by the user. In this case the combiner 7 produces on the display an image 8 consisting of the background image 1 and the triangle 3 obtained from image level 2 and placed onto the background picture. If the user wanted to change and display image level 1, he would use signal 9 to guide controllers 5 and 6 to set image level 1 to be fully visible (100%) and image level 3 to be invisible (0%). In that case the combiner 7 would produce an image with the ellipsis 2 on top of the rectangle 1 on the display.

[0016] As will be described in greater detail below, the principle of Figure 1 can be applied in most diverse transmission systems. Figure 2 shows an embodiment of the invention in which image information comprising a plural number of image levels is transmitted through the DVB network. Image levels of Figure 1 comprising the rectangle 1 in the background image, the ellipsis 2 on image level 1 and the triangle 3 on image level 2 are produced by the service or content provider at the transmitting end. The information relating to each image level is preferably supplied to encryption units 21 , 22 and 23, in which each image level can be separately encrypted. The image levels are then combined in a combiner 24 to provide a single transmission 25 comprising the information of all the image levels to be transferred (in this case the rectangle 1 , the ellipsis 2 and the triangle 3). This combined transmission 25 is transferred through the DVB transmit network 20 to a receiver in which a separator 26 separates the different image levels from the combined transmission 25 and supplies them to decoders 27, 28 and 29 which decode the encoding, if any. Each decoded piece of image level information is then supplied to the respective visibility controller 4, 5, or 6 which sets each image level to be visible or invisible, according to the user's commands, as described in connection with Figure 1. The different pieces of image level information are then supplied to the combiner 7 to form an image 8, as in Figure 1 , for display. If the encryption units 21 , 22 and 23 use their own codes to encrypt the separate image levels, the receivers are only able to use those image levels for which they have the correct code. Otherwise decryption is not possible. [0017] One way to carry out the transfer and/or encryption of the image levels is to use colour codes. A separate colour code, or codes, is used for each image level, and the receiver repeats the information related to the code only if the image level in question has been selected. For example, the background image of Figures 1 and 2 could be transferred using a standard blue colour code (OOOOFF), image level 1 using a red colour code (FFOOOO) and image level 2 using a green colour code (008000). In that case, the receiver in the example of Figure 1 would set red to be invisible or transparent, and the image compiled on the display would consist of a blue rectangle 1 and a green triangle 3. When changing the image level, the receiver would set green to be invisible or transparent and red visible, in which case the combination 8 would consist of a blue rectangle and a red ellipsis. However, the received broadcast would comprise all three colours and three image levels. This transfer of image levels can be carried out with any colour codes or colour code ranges. In an embodiment of the invention, standard colour codes are converted to a format which is unknown to ordinary receivers, for example a blue colour code could be converted to ABFOFF, a red colour code to FFOABC, and a green colour code to AB8000. A receiver supporting the image level concept of the invention would identify the colour codes of the different image levels and convert them back to standard colour codes supported by the receiver application, at the same time as the visibility or transparency of the image levels is being set. The converted standard colour codes are then supplied to the end application, which displays the image levels selected by the user.

[0018] Figure 3 shows one example of the content of the background image and image levels 1 to 2 of Figures 1 and 2. The background 1 is transmitted using the blue colour code, for example, and it comprises advertisement title fields 31 associated with electronic commerce. In Figure 3, the fields 31 show the name of the items to be sold (strawberries) and the user's address and telephone number. The content of the title fields 31 , in this case the name and telephone number of the farm, are transmitted on image level 1 (using red text, for example). On image level 2, blue text colour, for example, is used for transmitting alternative title field content 33 of the background image 1 , in this case the name and telephone number of a farm 2. All the information 31 , 32 and 33 is transmitted to the receiver, where the user selects the desired image level which is displayed together with the background image on the display. In this case the combined image 8 consists of the background image together with the title fields and the content 32 of image level 1. Image level 2 has not been selected and remains therefore invisible. The user may browse the address information of different farms simply by changing the image level. The colour coding of the image levels can be changed in the application, and the data of the selected image level can also be displayed using always the same colour. The application can also be implemented to provide adjustable transparency of the background image level. An adjustable background image level allows a TV program, for example, to be viewed through the background image. [0019] Figure 4 illustrates an interactive system in which the image information is sent to the receiver through the DVB system 20. In other words, a radio-frequency broadcast 45 is transmitted from a transmit antenna 44 to a reception antenna 46 connected to a terminal 43 in the digital TV system, for example, such as a Set-Top Box (STB) or a digital television set. The digital TV terminal is in turn connected via a network terminal 42, such as a modem, to the public switched telephone network or to another transmission system serving as an Internet return channel 41 for the content server 40. The content server 40 generates image level information according to the invention, the information being transmitted through the DVB system 20 to the receiver. The Internet return channel allows the user of the digital television terminal 43 to submit inquiries to the server 40 to examine the information provided by the vendors of a desired product, for example, the replies to the inquiries being transmitted back to the receiver through the transmission system 20. This arrangement allows for example electronic commerce to be carried out such that the information of all vendors of a particular product can be sent to the recipient by using a single background image and a plural number of image levels containing the actual changing content. This allows for more efficient data transfer and quicker browsing than conventional solutions in which each time a background image is sent it is accompanied by a different text version. In the case illustrated in Figure 3, for example, the combined image 8 would be sent twice, first provided with the information associated with the background image and state 1 and then with information of the background image and state 2. In a WWW application, for example, separate HTML pages would need to be transmitted for displaying the background image and state 1 and for displaying the background image and the information associated with state 2. According to the invention, both the background image and the information associated with states 1 and 2 are transmitted once in the same transmission or document, from which the browser then selects the image level desired by the user. In the following, this embodiment will be examined in greater detail. [0020] The interactive system of Figure 4 can also be used more generally for providing services applying the concept of the invention. The services reside on an Internet or media server 40 and they are provided to the clients' terminals 43 for selection in the form of an Internet service or as a broadcast through an electronic program guide, for example. A client communicating with the server 40 over the Internet return channel selects a service and, in response, he receives the colour code or image level code associated with the service. These codes may be liable to a charge or they may be optional. In a digital television system, for example, the services in question might include sub-titling, banner advertisements or competition rules associated with a program, for example, which may be displayed or remain hidden, according to choice. A most concrete example of the opportunities provided by the present invention is a game application which will be described in greater detail below. In the game application, the levels to be selected for display can be used as a platform for games in the Internet or in a digital TV system. In a strategy game, for example, a module of the game program can be downloaded to the client's computer and it provides the functions of the game and the game world platform for use to the player. Each player will have a separate image level, which is shown on top of the game platform. As is characteristic of strategy games, the player builds his own world according to the functions of the game on his image level provided through the transfer network. The system architecture may be like the one shown in Figure 4, for example, if the image information is sent through the DVB system and the return connection 41 is implemented through a telecommunications system. Information associated with each player's own image level alone needs to be transmitted over the return channel 41, not the entire image. Correspondingly, the server 40 needs to store and manage only the information associated with the image level of each player, whereby significant savings in resources are obtained. Similarly, when the player moves in the game from his own field to another field where there is already for example two players, i.e. moves from one image level to another, it is sufficient to only send the image level information through the DVB system and not the information associated with the entire image (i.e. including the background image). This game application assumes that the game platform underneath the image level remains the unchanged and only the information relating to the players' image levels can be influenced, i.e. that changes as the game proceeds.

[0021] The block diagrams of Figures 5A and 5B illustrate a game application, which is described with reference to the system architecture shown in Figure 4. The terminal 43 receives a DVB transmission 45 in which an electronic program guide EPG offers a network game (step 500). The user selects the game offered by the EPG and the game is downloaded from the DVB system to the client terminal 43 (step 502). The user starts the game by pressing the "start game" key and the terminal 43 sets up a connection through the return channel 41 to the server 40 (step 504). The server 40 provides player X with an image level in which the player will operate in the image information transmitted over the DVB network (step 506). The player takes into the use the resources of the image level provided and builds game resources until he reaches a port construction level (step 508). At this stage the Internet return connection 41 may be inactive, i.e. in an off-line mode. Nevertheless, the terminal may update the image level information supplied to it (the game resources it has built) to the server 40 either by own initiative or in response to a connection set-up request received from the DVB system (510). The object in the game is to conquer the opponent's image level, which can be accessed through a specific port. Before moving to the other player's image level, player X selects the game resources he needs to take with him (step 514). Player X then goes through the port and enters a game level used by player Y and either created earlier or after player X entered it (step 516). At this stage the Internet connection 41 to the server 40 is active, and the game resources player X brought with him to the game level are uploaded to the server 40. Next, the image level of player Y is downloaded to player X from the server 40 through the DVB network and the game resources brought by player X are loaded to the image level (step 518). As shown in Figure 5B, player X then tries to conquer the image level of player Y (step 520). In this game, the image information associated with the game is sent to the terminal 43 through the DVB network (forward traffic) and the return traffic from the server 43 to the server 40 takes place through the connection 41. Player X has a movable port through which he can escape, if necessary, from the image level of player Y back to his own image level, taking his resources with him (step 522). The game then returns to point A (step 512) in Figure 5A. If player X loses, i.e. player Y destroys all the game resources of the player X on player Y's own image level (step 524), the image level of player X is returned on the display (step 526). If player X wins, i.e. destroys the resources of player Y on player Y's image level and thus conquers Y's image level (step 528), player X moves to a new image level (of player Y or some other player) and builds more resources there to conquer that image level (step 530). At the same time, player Y returns to a previous image level, provided that he has one. Otherwise player Y will have to start a new game (step 532).

[0022] In the following, some examples of how the level technology of the invention can be implemented in the DVB system are illustrated. The implementation alternatives can be divided into two main categories:

A) Use of level technology is implemented at user application level without changes to data transmission services. B) Use of level technology is implemented by complementing the service specifications of the DVB standard such that the image elements of the different image levels are defined in SI and/or PSI files and transmitted. The image level to which a particular service is associated with is indicated in the different services and in the SI and/or PSI information. [0023] DVB services are defined in greater detail in SDT service descriptions. When image elements to be transferred in the DVB service are to be defined for the different levels in the metadata describing DVB services, this is carried out in the descriptor tables of the SDT services. Depending on the service used for transferring the image elements associated with the different image levels, a definition given in the metalanguage in the descriptor table of the corresponding service is used, which definition is either not defined in advance or it can be defined by the client and which, according to the invention, is agreed to define the image level of image element to be transferred. The invention is particularly well suitable for use in data services in the DVB.

[0024] Resources can be reserved from the DVB for data services of significant capacity in the following ways. 1. Data Piping for anonymous asynchronous services; 2. Data Streaming for synchronous or synchronized transfer of a bit stream; 3. Use of Multiprotocol Encapsulation DVB system for diverse telecommunications system services; 4. Data Carousel for periodic transfer of data files; if teletext pages are transferred as files, they are transferred using the data carousel. In addition to the above four, an object carousel for object broadcasting has been defined in accordance with the Network Independent Protocol specification of the DVB. [0025] The use of Data Carousel will be described below as an example of the use of the DVB data transfer service in a system employing image levels, although any other transfer method can also be used by employing the metadata allowed for in the descriptor table of each particular service for defining the image level. [0026] In the DVB system data can be transferred using a data carousel, for example. The data carousel is a hierarchical structure in which download datablocks (DDB) are assembled into data modules which in turn form a data group. The simplest version of the data carousel comprises only one control level which defines one data group. However, the data carousel may also comprise a hierarchically higher control level representing one super group which consists of two or more data groups. The use of the data carousel is described in the service information (SI) of the DVB multiplex. To be more precise, the Service Description Table (SDT) and the Event Information Table (EIT) comprise a data_broadcast_description field which indicates a download info indication message. Each data group is provided with a separate download info indication message which also contains a description of the data service type which allows a data carousel telecommunications application in the receiver to convey the data to an application appropriate for processing the kind of data in question. Download info indication message is also used for informing the data carousel application of the receiver about the hierarchical structure of the data packets belonging to a specific data service in the carousel. More specifically, module info bytes fields (mi-fields) of the download info indication message refer to the data modules of the data service and to the data blocks of the modules. Using the data hierarchy information obtained, the application is able to reconstruct the transmitted message. [0027] In the following, an example of the implementing of image levels in the DVB system will be described with reference to a data carousel and to Figure 6, which is a block diagram of a DVB receiver of the invention.

[0028] The content service provider buys a data carousel service from the holder of a DVB multiplex (a television broadcast company, for example). The content service provider receives one data group, for example, from the data carousel for use, the data group comprising a plural number of data modules. In addition, SI information is provided, in the above described manner, with information which allows the receiver to find the modules and data blocks of the group. The data can be arranged in the data carousel such that each image level of the invention is supplied to a separate data module in the data carousel whereby, from the receivers' point of view, the data is provided with a clear structure which simplifies the constructing of the applications. The data carousel descriptor tables can be provided with a definition indicating the image level at which the data concerned resides. This can be carried out for example in a private data byte field, which is a user definable field in the download info indication message. This field can be provided with an image level identification Level-ID, for example.

[0029] With reference to Figure 6, a decoder 60 in the receiver decodes the multiplex in a manner known per se and guides the MPEG2 elementary stream, i.e. audio and video, to corresponding MPEG decoders 61 and 62. The data blocks of the data carousel the decoder 60 guides to data carousel telecommunications software 63. The data carousel software 63 compiles the data arriving in the data carousel by using the above mentioned information fields and guides them to appropriate applications, such as a Java application 64, teletext 65, e-mail 66 or web browser 67. The Java application 64 is a Java class, for example, which is downloaded from the carousel 63. To run the Java class, the class employs a Java virtual machine 68 which it uses for creating windows and a page map based on the image levels onto a display 71. On the basis of SI information, the carousel telecommunications software thus separates the data modules belonging to different image levels and supplies them to the Java application 64 through different ports. The Java application 64 supplies the data associated with the image levels to the Java virtual machine 68 which processes their visibility and transparency according to the specifications and selections transmitted by the user via user interface 72. Hence, the Java virtual machine 68 operates according to the same principle as the controllers 4, 5 and 6 in Figures 1 and 2. The image level information is then supplied to a multimedia compositor 69 which combines the image level (or levels) selected by the user with the video signal received from the MPEG2 video decoder 62. The combined image information is supplied to a display adapter 70 and shown on the display 71. The multimedia compositor 69 may for example store each image level graphics or text into a separate memory block and use them to generate the content of a display memory 70 according to the image levels and the display source code defined for display by the user interface 72. The use interface can be used for providing the user with a 'page map' of the image levels from which the user can select an active image level. Figure 7 shows the display 71 with a page map 81 on the top left- hand corner. The page map lists image levels 1 to 4 of which level 1 is active. At the same time, the display 71 also displays image information 82 of level 1. The user 1 can change the image level which is on the display (typically on top of the background image) by moving the cursor to a new level on the side map and by activating the level. The side map 81 may also be provided with a 'visibility' link from which the user can activate the visibility control of the different image levels. Visibility control can be provided for example as a menu like the one shown in Figure 8. Each level in the menu is provided with a separate controller 90 which allows visibility to be adjusted by moving the cursor 91 in the controller. The cursor 91 can be moved for example using a mouse or the arrow keys of a remote-control device. With a 100% absolute visibility, the pixels in the graphics of the image level in question are shown independently, the object being topmost. In several applications, 100% visibility of image levels is preferably used as background image visibility value, if the application concerned is meant to display a video program, for example, through the background image. When graphics of a 100% absolute image level is topmost, it covers completely the graphics underneath. In Figure 8 the visibility value of image level 1 is set at 100%. If the visibility value is set at 0%, as for levels 2 and 3 in Figure 8, these levels are not shown on the display at all. If the visibility value is set between 0% and 100%, the superposed image level pixels are summed according to the ratio of the visibility values. In Figure 8, levels 4 and 5 are given visibility values 61 % and 41 %, respectively. These are proportional values; the summed visibility value cannot exceed the absolute 100% value.

[0030] In the data carousel application described in connection with Figure 6, each image level was transferred in a separate data module and therefore the levels could be separated in the data carousel telecommunications software. Alternatively, however, the image levels can also be left to be separated by the application, such as the Java application 64. In that case the above described level information does not need to be added to the DVB system data. Instead, the actual application data to be transferred must be provided with suitable metadata informing the image level to which each data block belongs. Otherwise the receiver operation may be similar to that described above. However, this alternative provides an advantage in that the level technology of the invention is fully independent of the DVB system. The image-level separation taking place at the application level can be carried out using for example an extension of HTML and Java, to be described below, which allows the image levels to separated using the web browser 67.

[0031] The implementation of the level technology of the invention by complementing the specifications of the DVB standard can be carried out in all services employing PES packets for transferring data in a data service. Within each service, a sub_stream_id can be assigned for each image level, i.e. the data service can be divided among the image levels as a separate sub- service. This extension is possible because in the standard the use of the sub_stream_id has been left for the user to determine. [0032] For each image level to be associated with a separate service, the program must be composed of a plural number of services by using SI and PSI.

[0033] If the image levels of the services to be associated with different image levels are defined in the DVB transfer service, the defining is carried out in the SI information, i.e. in the metadata on the service in question given in the descriptor tables of the DVB transfer service. As described above, SI information comprises a service descriptor table (SDT) and an event information table (EIT) in which each service is identified using a service identifier service_id. Each SDT sub-table describes the services contained in a particular transfer stream TS. The event information table EIT comprises data relating to events or programs, such as their duration, starting time or the title of the event. In addition, the EIT allows event information of different types to be sent. These service identifiers servicejd allow the services related to each image level to be identified in the decoder of the DVB receiver and the data to be directed to the correct destination. The SI information also allows the decoder of the receiver to be configured to correspond to the technical data of the service in question.

[0034] By defining image levels to the different data service sub- streams, it is possible to prioritize data service portions. The prioritization of video services by means of image levels can be implemented by adding the image levels to the events according to the following example.

[0035] A DVB service may be composed of events having a beginning and an end. This approach can be used when the sending and displaying of events is prioritized using the image level technology of the invention. Each event (such as a news item) is assigned a separate image level such that new, important news are always broadcast at image level 1 , and repeat broadcasts and less important news at lower image levels. For example, a person watching a movie through a personal TV system (the mass memory of the set top box functioning as a buffer memory), he may select news items of image level 1 that are broadcast during the movie for display. When a new, important news item of image level 1 is received during the movie, the movie is interrupted and the news broadcast is brought to the display. When the news event is completed, the mass memory allows the watching of the movie to be continued exactly from the point where it was interrupted. Another alternative is that news prioritized using the image levels are edited in the form of banners, for example, in which case the banner appears on the display on top of the movie. Further, the selection based on prioritizing programs with image levels can be used when a new service is to be composed of a program. For example, a real-time service (image level 1) of a stock exchange news service can be encrypted, and the same news can be sent without encryption when they arrive later through the service provider on image level 2. From the point of view of the image provider it is also possible to send a summary of the news at image level 1 , complementing additional details being then sent at lower image levels. The client may act as an interactive viewer by selecting in-depth information with the image levels, and, similarly, holders of a DVB multiplex can compose their program sets by selecting a desired number of content portions prioritized with the image levels for their broadcast. In a personal TV device, image-level prioritization can also be used for selecting program services to be recorded. To indicate prioritization as an image level is a matter of agreement, although it is logical, because in practice the image level principle and the image level technology of the invention are implemented when a banner, for example, is composed on top of another image.

[0036] The video image transfer of the invention on different image levels can also be used in connection with a mosaic service. A mosaic component is a collection of different video images forming a coded MBEG2 video stream. The video images are attached already at the transmitting end such that when displayed, each image takes up a specific portion of the display. This portion is referred to as a logical cell. Logical cells are composed of basic cells. A mosaic display can be divided into 8 x 8 basic cells at the most. A logical cell is a collection of basic cells which is defined using a specific mosaic identifier. As stated above, in this known mosaic service, the location, number and size of images on the display are determined already at the transmitting end. With the level technology according to the present invention, each video image can be sent at its own level and hence a video image can be selected through the user interface for each mosaic service square from the images of different levels determined in the basic cell. [0037] The level technology of the invention based on colour codes can also be used in connection with teletext. Instead of a standard colour code, part of a teletext service is combined with the teletext data stream of the service coded in colours that cannot be made visible without a change to a standard colour. In the service of the invention, the colour-coded portion of the pages is transmitted either as a separate teletext service or as a part of the service transmitted using the standard colour code. This procedure allows the teletext service to be extended with services liable to a charge. To be able to receive the service, the receiver is provided with an application or equipment capable of performing said colour code changes, and with information about the colour codes used in the TV broadcast is obtained.

[0038] The image level technology of the present invention is also applicable in other transmission system than the DVB. It can be used for example with an ordinary Internet connection between a WWW server and a client computer. As described above, in an ordinary metalanguage document, such as a document drawn up in HTML, the mark-up language defines how the client's web browser is to display the document on the display. For this purpose, the document comprises diverse definition tags, such as <p>, which indicates the beginning and end of a paragraph. According to the invention, a document content code can be provided with definitions indicating the level of the content of a particular page. This may take place for example by placing a new tag <layer> at the beginning and end of a document that is to be assigned a specific image level. Consequently, the client's web browser does not display the entire content of the document, but only the levels selected by the user. Most of the HTML document may consist of a background image, for example, which is not given a separate level specification, i.e. it must be shown by default. In addition, to document is provided with image levels comprising optional information which the user may activate to be visible or deactivate to be invisible. The browser may also display a page map showing the different levels on the display, similarly as the page map 81 in Figure 7. The user may selected the desired level from the page map 81 and activate that, as a result of which the content of the HTML page shown on the display will change. The browser may also be provided with the visibility or transparency control shown in Figure 8, for example. Another alternative is to set transparency in the programming code, for example as follows: <!docktype html public"-//w3c//dtd html 4.0 transitional//en"> <html> <head>

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">

<meta name="Author" content="Risto Makipaa">

<meta name="GENERATOR"content="Mozilla/4.72[en](Win98;l)

[Netscape]">

<Layer 1 Opacity = 100>

<Layer 2 Opacity = 0>

<Layer 3 Opacity = 0>

<title>lm , &ouml ;</title> </head> <body background="image.gif&>

[0039] Another alternative for moving from one image level to another in an HTML document is to use links embedded in the document. When the user activates a link referring to an image level through the user interface of the browser, the image level in question is displayed.

[0040] The following example illustrates layer specification in an HTML code:

<layer1 > HTML code for layer 1

<set layerl opacity- ' 100" order="top">

<layer2:> HTML code for layer 2

<set Iayer2 opacity="0" order="top">

<layer3:> HTML code for layer 3

<set Iayer3 opacity="0" order="top">

[0041] For interactive applications and applets the browser must create windows on the display, in addition to the HTML language. The Java language provides an abstract windowing tool kit (AWT) containing classes for constructing a Java graphical user interface. These classes may be referred to as components. A component class contains ordinary basic window components and menus. These classes are included in the above mentioned Java AWT. In the Java, Panel, Applet, Window or Frame components are arranged inside a Container component. Each user interface implemented using the Java language contains at least one Container component into which other components can be placed. To allow image levels to be used for displaying these components, new methods must be added to the Java software to allow the desired image to be defined. This can be carried out for example as follows:

import Java. awt.*; import java.awt.event.*; public class sample extends java.awt. Frame implements Action Listener, WindowListener {

Button b1 ; Text Field t1;

Public SampleO { this.setLayout(nulI); t1 = new TextField("l am a text field"); this.add(tl); t1.setBounds(50,50, 150,30); b1 = new Buttonf'Press to exit"); this.add(bl); b1.setBounds(50, 100,150,50); b1.addActionListener(this); this.setBounds(10,10,250,250); this.addWindowListener(this); this.setLayer(l) //New method for defining component image level this.setOpticity(100%) //New method for defining component transparency this.setVisible(true); } public void action Performed (ActionEvent anEvent) { if(anEvent.getSource()==b1) t1.setText(anEvent.getSource().toString()); return;

} public static void main (String args[]) { new Sample();

}

} public void windowclosing (windowEvent anEvent) { System. exit(O);

Return;

} public void window windoclosing (windowEvent anEvent) {

Return; } public void windowDeiconified (windowEvent anEvent) {

Return;

} public void windowDeiconified (windowEvent anEvent) { Return;

} public void windowOpened (windowEvent anEvent) { Return;

} public void windowActivated (windowEvent anEvent) {

Return;

} public void windowDeactivated (windowEvent anEvent) {

Return; }

}

[0042] If each one of the components in the Container component is to be described on a separate image level, the image level definition must be carried out component-specifically, for example as follows:

import java.awt.* import java.awt.event.*; public class sample extends java.awt.Frame implements Action Listener, WindowListener {

Button b1 ; TextField -1 ;

Public SampleO { this.setLayout(null); t1 = new TextField("l am a text field"); this.add(tl); t1.setBounds(50,50,150,30); t1.setLayer(1); //component-specific image level definition b1 = new Button("Press to exit"); this.add(bl); b1.setBounds(50, 100,150,50); b1.setLayer(1); // component-specific image level definition b1.addActionϋstener(this); this.setBounds(10,10,250,250); this.addWindowListener(this); this.setVisible(true);

} public void actionPerformed (ActionEvent anEvent) { if(anEvent.getSource()==b1) t1.setText(anEvent.getSource().toString()); return;

} public static void main (String args[]) { new SampleO;

} } public void windowclosing (windowEvent anEvent) {

System. exit(0);

Return;

} public void window windoclosing (windowEvent anEvent) {

Return; } public void windowDeiconified (windowEvent anEvent) { Return;

} public void windowDeiconified (windowEvent anEvent) {

Return;

} public void windowOpened (windowEvent anEvent) {

Return; } public void windowActivated (windowEvent anEvent) {

Return;

} public void windowDeactivated (windowEvent anEvent) { Return;

}

}

[0043] The DVB standard specifies a Multimedia Home Platform defining an application platform for multimedia applications. The definition includes a Java class which the standard terminal must support. The above described methods for determining image levels into a Java code are applicable in Java applications which are downloaded through a telecommunications system to a terminal and which employ image levels from which the client selects the desired image elements on the display according to the image levels. This requires that the Java class supported by the MHP and the Java virtual machine comprise support for the image levels defined in the Java code.

[0044] Instead of the image level definitions described above, or in addition to them, image levels can also be determined in a received electronic document by means of a colour code. Display adapters and applications, such as web browsers, each identify a specific set of colour codes, i.e. their own standard codes. If a content code is composed using other colour code values than standard codes, the display adapters and applications do not identify them and thus they cannot be shown as such on the display. On account of this, image levels can be included in the image information sent to the receiver by using colour code values deviating from the standard colour codes, and hence only devices and programs entitled to use image levels will be able to convert them into colours conforming to the standard and thereby make them visible on the display. In other words, the receiver must know the colour code conversion function and the related parameters. By using non-standard colour codes, the content of the image level in question is in a way encrypted. To carry out the colour code conversion, the web server or the client application could inquire about the conversion parameters of the software carrying out the colour code transform as a service access data. If the conversion is performed at the client's end, then encryption is particularly well suitable for broadcast- type transmissions because return traffic is not needed for the decryption. Colour code conversion provides light encryption which is particularly efficient from the point of view of network capacity use, because additional bits are not required in the transmission. The conversion function may take for example the following form:

standard colour = F (HTML code colour, conversion parameter)

[0045] Displays have about 32,500,500 colours and corresponding codes in use. All in all, an unlimited number of colour codes could be used and the conversion function for the colour code conversion could also be freely selected. The conversion function can be implemented as a software module to be attached to the client application. The browser application can also be complemented such that it bypasses graphic codes which are not identified.

[0046] In the above examples the described HTML documents (or documents composed using another programming language) are typically maintained on a WWW server located in the Internet, such as the server 40 in Figure 4. The client computer browser contacts the server in a conventional manner, and the requested WWW page can be transferred from the server with the browser similarly as in current solutions. The only difference is that a plural number of image levels to be displayed at different times are now transferred together with the document. The client computer browser being provided with software capable of separating the different image levels from one another, the user can activate different image levels to the display, as described above. It is to be noted that a metalanguage page can be distributed to the client computer also through the broadcast system. In that case it can be conveyed in the DVB receiver to a web browser 67, for example, which supports the functionality of the invention. The web browser 67 thus shows on the display 71 a combination image comprising the image levels selected by the user.

[0047] The above specification is only meant to illustrate the present invention. The details of the invention may vary within the scope and spirit of the accompanying claims.

Claims

1. A method for transmitting image information in a transmission system, such as a telecommunications system or a broadcast system 820), the method comprising the steps of transmitting image information (25) through the transmission system

(20) from a transmitting end to a receiving end; displaying the received image information on a display (71) at the receiving end, characterized by further comprising the steps of transmitting two or more image levels (1,2,3) simultaneously, enabling the user to selectively choose or combine (4,5,6) desired image combination (8) onto the display by selecting a specific image level or specific levels to be visible and a leaving remaining image level or levels invisible.

2. A method according to claim 1, characterized by comprising the steps of transmitting metadata describing the service through the transmission system from the transmitting end to the receiving end; transmitting two or more image levels (1,2,3) simultaneously, the levels being defined and referred to using said metadata and the user being able to selectively choose or combine desired image combinations onto the display (71) by selecting a specific image level or specific levels to be visible and leaving another image level or other levels invisible.

3. A method according to claim 2, characterized in that service metadata describes a data transfer service of the transmission system, transmitted metadata being used for determining at least one service for an additional image level (1,2,3), which is displayed or not, according to the user's choices, on the display on top of image information provided by some other service .

4. A method according to claim 3, characterized in that at least one of the image levels (1,2,3) consists of video information transmitted from the transmitting end to the receiving end; at least one additional image level is transmitted in addition to said video information, the image level being displayed or not, according to the user's choices, on the display (71) on top of the video information.

5. A method according to claim 4, characterized by comprising the steps of transmitting said at least one image level (1 ,2,3) coded into colour codes that the video information comprises; decoding at the receiving end said at least one image level from said colour codes and displaying the level according to the user's choices on the display on top of the video information.

6. A method according to claim ^characterized in that at least one of the image levels (1,2,3) consists of video information which is sent from the transmitting end to the receiving end; transmitting at least one additional image level, in addition to said video information, which is displayed or not, according to the user's choices on the display on top of the video information.

7. A method according to claim 6, characterized by comprising the steps of transmitting said at least one image level coded into said video information; decoding said at least one image level from the received video signal and displaying the level according to the user's choices on the display on top of the video information.

8. A method according to claim 7, characterized by comprising the steps of transmitting said at least one image level coded into colour codes that the video information comprises; decoding said at least one image level at the receiving end from said colour codes and displaying the level according to the user's choices on the display (71) on top of the video information.

9. A method according to claim 8, characterized by comprising the steps of transmitting the image level using a predetermined colour code for the level in the video signal; identifying said predetermined colour code at the receiving end as a code associated with the image level in question; displaying said image level on top of said video information only if the user selects said image level for display, whereas otherwise the image level is not displayed.

10. A method according to claim 6, characterized by comprising the steps of transmitting said at least one image level in a data stream associated with said video information, and either separating from the received data stream the image level selected by the user and displaying that on the display with the video information, or displaying on the display the video information as such, if the user does not select any of said at least one additional image level.

11. A method according to claim 10, characterized in that said video information is transmitted on a program channel of a digital broadcast system (20) and said data stream is transmitted in a single data transfer service; said data stream is routed (63) to an application (64) corresponding to the data transfer service in question at the receiving end; separating data associated with the image level selected by the user from the data stream in said application (64) and displaying the image level on the display (71)on top of said video information.

12. A method according to claim 10, characterized in that said video information is transmitted on a program channel of the digital video broadcast system (20) and the data stream comprising the image levels are transmitted in a single data transfer service in which a separate sub- data stream is determined for each image level; the receiver is arranged to separate (63) the sub-data flows from one another and to forward the image level selected by the user for display on the display (71) with the video information.

13. A method according to any one of the preceding claims, characterized in that the video information provides a background image and other image levels are optional image levels which can be displayed on the display on top of the background image according to the user's choice.

14. A method according to any one of claims 6 to 12, characterized in that in addition to said video information, at least two image levels are transferred, one of the image levels forming the background image (1), while the other image levels (2,3) are optional levels that can be displayed on the display on top of the background image (1) according to the user's choice, in which case the background images and other image levels are defined to be substantially transparent on the display.

15. A method according to claim 1 or any one of claims 6 to 14, characterized in that one of the image levels is a background image of an interactive network game, the image being shared by all users playing the network game; said other image levels are those of the individual players, the levels being used for displaying game events relating to the player in question and selected player-specifically such that each player is shown only the player's own game level, and possibly that of the opponent.

16. A method according to claim 1 or any one of claims 6 to 14, characterized in that one of the image levels is a background image (1) which comprises information such as information field titles (31) and which can be used as a common background for a plural number of other image levels; said image levels (2,3) comprise alternative contents, such as contents (32,33) of information fields included in the background image, which can be shown on top of the background image (1) according to the user's choice.

17. A method according to claim 1 or any one of claims 6 to 14, characterized in that the image levels comprise sub-titling which the user may select on top of the actual video information.

18. A method according to claim 1 or 2, characterized in that the service metadata is located in a metalanguage document of a file transferred over the transmission system from the transmitting end to the receiving end; the transferred metadata is used for determining at least one image element described in the document for an additional image level which is selected or not, according to the user's choices, for display on the display on top of image information produced by another service.

19. A method according to claim 1,2 or 18, characterized in that the service metadata is compiled in HTML; and at least one content part of the document is determined using a metalanguage level definition for an additional image level, the image level being displayed or not, according to the user's choices, on the display on top of image information produced by another service.

20. A method according to claim 1,2 or 18, characterized in that the service metadata is included in a document which belongs to a

Java class and at least one content part of the document is determined using a metalanguage level definition for an additional image level which is displayed or not, according to the user's choices, on the display on top of image information produced by another service.

21. Receiver equipment for receiving image information over a transmission system, such as a telecommunications system or broadcast system, and for displaying the information on a terminal display, characterized in that the receiver equipment comprises program modules for identifying metalanguage references describing a data transfer service, the references determining an image level for service or content parts of a document, and that the receiver equipment comprises program modules for providing the above mentioned desired image levels as selection alternatives when images and image combinations are being selected from the user interface onto a display.

22. Receiver equipment for receiving image information over a transmission system, such as a telecommunications system or broadcast system, and for displaying the information on a terminal display, characterized in that the received information comprises, in addition to primary image information, at least one additional image level (1,2,3) and that the device is arranged (68,69,72) to display or not to display the at least one additional image level, according to the user's choices, on the display (71) on top of the primary image information.

23. Equipment according to claim 21 or 22, c h a r a c t e r i z e d in that the equipment is a receiver (43) in a digital video broadcast network.

24. Equipment according to claim 21, 22, 23 or 24, characterized in that the equipment (43) comprises an Internet browser (67).

25. Equipment according to claim 21, 22 or 24, characterized in that the image information is a metalanguage document, such as an HTML document, which comprises primary image information that is always displayed and at least one additional image level defined with a metacode, the image level being made visible only when the browser is set to also display this image level.

26. Equipment according to any one of claims 21 to 25, characterized in that the different image levels employ different colour codes.

27. Equipment according to any one of claims 21 to 26, characterized in that the equipment separates the image levels from one another on a higher transmission system application level (64, 67), such as a browser (67).

28. Transmitter equipment for transmitting image information through a transmission system, such as a telecommunications system or broadcast system (20), to user equipment for display to the user on a display, characterized in that two or more image levels (1 ,2,3) are transmitted simultaneously from which the user is allowed to selectively choose or combine desired image entities (8) onto the display (71) by selecting a specific image level or specific levels to be visible and leaving another image level or other levels invisible.

29. Transmitter equipment according to claim 28, characterized in that one of the image levels (1,2,3) comprises primary image information, such as a video signal, and that, in addition to the primary image information, at least one additional image level is transmitted which is displayed or not, according to the user's choices, on the display on top of the primary image information.

30. Transmitter equipment according to claim 28 or 29, characterized in that the equipment is an Internet server (40).

31. Transmitter equipment according to claim 29 or 30, characterized in that the equipment is a transmitter in a digital video broadcast network.

32. Transmitter equipment according to claim 28, 29 or 30, characterized in that the image information is a metalanguage document, such as an HTML document, which comprises primary image information that always displayed and at least an additional image level defined with a metacode, the image level being made visible only when the browser of the user's equipment is set to display this image level as well.

33. A transmit device according to claim 32, characterized in that different image levels employ different colour codes.

34. A metalanguage document to be transmitted through a transmission system, such as a telecommunications system or a broadcast system, to user equipment for display to the user on a display, characterized in that the metalanguage document, such as an HTML document, comprises primary image information that is always displayed and at least an additional image level defined with a metacode, the image level being made visible only when the browser of the user's equipment is set to display this image level as well.

35. Transmitter equipment according to claim 34, characterized in that the different image levels employ different colour codes.