WO1994003793A1

WO1994003793A1 - Method for determining the kind and distribution of tissue in living organisms

Info

Publication number: WO1994003793A1
Application number: PCT/NO1993/000122
Authority: WO
Inventors: Torbjörn HALLGREN; Leif Bjerkan; Bernt Brandal; Noralf Ryen; Nils Harald BJÖRSHOL
Original assignee: Sinvent As
Priority date: 1992-08-07
Filing date: 1993-08-04
Publication date: 1994-02-17
Also published as: EP0654143A1; NO923094L; NO923094D0

Abstract

In a method for determining the kind and distribution of tissue in living organisms (1), especially the food content in e.g. crabs, the organism (1) is situated between a light source (2) for visible and infrared light, and a camera (3) connected to a computer (4). The organism (1) is candled by the visible and infrared light, the camera (3) is registrating this candeling, and the result is analysed by the computer (4). The camera (3) shoots a plane image of the object in one or more wavelength ranges, and data derived from the image or the images is analysed, by, in particular, comparing data descriptive of regions of the registered images, to corresponding data from images of corresponding objects of known quality. Based upon this analysis, the objects are sorted into predetermined quality classes.

Description

Method for determining the kind and distribution of tissue in living organisms.

The present invention relates to a method for determining the kind and distribution of tissue in living organisms, as stated in the introductory part of claim 1.

There have been developed a number of methods for investigation of organic tissue. Many of these methods can only be used with dead tissue. Candling of fish fillets using visible light to uncover remaining bones, is a well known example of such a method. The method is manual or automatic, and is conducted by the fish fillet being transported over a backlit transparent glass plate. The pieces which do not satisfy certain standards, are rejected. Candling of eggs is another example. However, the candling methods generally cannot be used in a simple manner with living, undivided organisms which in practice are often impenetrable by light. Candling investigations by a human observator may also lead to great stress for the person performing the work, since a very strong light must be used.

For living material, it is known to use X-rays and ultra sound. X-rays have the disadvantage that extensive shading must be put in place. For ultra sound difficulties arise due to the interferance noise in the method. The method is also poor in differentiating between tissues having the same density.

The article "Protein, fett og vann i fisk kan males ved infrarødt lys", by Henning M. Sollid, Fiskeriforskning nr. 1, 1991, describes the use of a more general analytical technique used in fish. The method is called "Near Infrared Transmision" (NIT). The method uses a beam of infrared light transmitted through a sample of crushed tissue, as in this case, of salmon fillet. The sample is of a standarised shape and size. The instrument is successivaly transmits light having 100 defined wavelengths throught the sample. The individual materials in the sample will influence the infrared light. The influence will vary with the wavelength in a way which is specific for the material that is measured. The part of the light which shines through the sample is registered and the result is processed in a computer. The measuring results are compared with stored comparative values for matter to be measured. The comparative values are determined by conducting measurements in a great number of samples which then are analysed chemically. The method is an alternative to routine chemical analysis. The method is well suited for homogeneous material but can not be used in a section where tissues of different kinds are present. Therefore, it can also not be used for living organisms.

For some animals, e.g. crabs, it is preferred to be able to evaluate the food content before slaughtering. Today this is performed as a rough estimate and with a great deal of uncertainity. It is of interest to be able to take crabs which are not approved, back to feeding.

It is therefore an object with present invention to provide a method which can be used to determine tissues distributed in regions of living organisms.

The object of the invention is acheived with a method having features as stated in the characterizing part of patent claim 1. Further features will be clear from the dependent claims.

In the following the invention shall be described in more detail using an example of an embodiment and with reference to the enclosed drawings in which:

Fig. la discloses the principle for equipment for conducting a method according to present invention,

Fig. lb discloses the principle of alternative equipment for conducting a method according to present invention,

Fig. 2 shows an object which is to be measured using a method according to present invention, Fig. 3 shows an example of arranging a light source for use in connection with present invention, and

Fig. 4 shows an example of an arrangement of a video camera for use in connection with present invention.

Fig. la shows an arrangement for measuring living organisms according to present invention. A crab 1 is situated at a transparent plate 6, and a light source 2 is placed under the plate. The light passing through the crab is regisered by a video camera 3. The images from the camera are digitized and processed using a computer 4.

The light source 2 can be a halogen incandescent lamp which emits strong radiation in the wavelength range 400 to 2000 nm. Between the object 1 and the camera 3, a filter 5 can be situated, the filter being exchangeable thereby making it possible to choose light in different wavelength bands. The transparent plate 6 can be a clear glass plate or a translucent or dim glass plate. If a clear glass plate is used, light from the light source 2 is spread e.g. using the focus collimator 7 or a spreading lens. The dim glass plate or the collimator helps spreading or diffuse the light so that light source 2 is "hidden" to the camera. Another way in "hiding" the light source, is to use an objective having so narrow focus that the crab itself covers the lightsource.

The plate 6 is a type of glass which does not loose much transparency in the wave¬ length area in question. At suitable time intervals, the plate should be washed with water, and this water should be swept away. In the vicinity of the object 1, one or more gray references 8 may be placed, such as a gray filter which is trans- illuminated.

The transparent plate can be exchanged by a grid made from a non-refracting and non-reflecting material. This grid can be a conveyor, so that mechanisms for transporting the crab to and from the glass plate can be avoided. Measurements are conducted after the crab has been drugged, so that it would lies calmly on the glass plate 6. This can be done by cooling, e.g. using carbon ice. The light from the light source 2 is switched on, and a candle image is registered by the camera 3. Optionally the filter 5 can be exchanged and a new measurement performed. One or more measurements can be performed. When a plurality of measurements are done, the measurements are taken in different wavelength ranges. The first measurement may e.g. be conducted using light in the range 400 to 900 n and the second measurement in the range 1400 to 1600 nm. The measurements are thus performed in the range from visible light and up to the infrared range. If there is a great variation in the density from measured object to measured object, it may be necessary to change the aperture adjustment or the integration time for the camera 3. To compensate for this, either the known reference 8 for grey shades is measured together with the object, or changes in camera parameters are known because they are controlled by the computer. Corrections can thus be computed. When measuring with the arrangement in Fig. la, the crab lies with its upper side up (directed to the camera). Fig. lb shows a variant of the measuring arrangement. As an alternative to drugging the crab, it can be put on its back during measurement. In this case the light source is situated above, and the camera below the measuring object, so that the crab is once again directed with its upper side toward the camera. Fig. 3 illustrates a possible way of arranging the light source. The light source 2 itself is situated within a container 21. The light emits through an aperture 22, having a size which can be selected for the size of the object being measured, so that no aperture is visible from the camera. The plane 23 in which the aperture is situated, is extended in area so that it covers the whole visible area of the camera. The plane is arranged with a light trap 24 so that a dark background is provided. Optionally, a collimator 7 or a spreading lens can be situated in the aperture opening. Fig. 4 shows a possible way to arrange the camera. The camera 3 is situated within a container 31 which is arranged so that light which enters cannot exit. In this way undesired, reflected light on the upper side of the crab is avoided. The container is black inside. It has a flange 32 with a light trap 34. Also in the bottom, a light trap 33 is situated. When the measuring arrangement is according to Fig. lb, the transparent glass plate will lie directly on the flange 32. The light trap 34 is then not necessary. However, if the measurement arrangement in Fig. la is used, the light trap 34 will hinder reflection or spread of light on the upper side of the crab.

The method of measurment is that images are taken of the object 1. The following quality determination is conducted in the computer 4 using n mearsuring values which among other things will show sex, size, transmission in different areas and form and shape of these areas. The measured values are compared to previously stored comparision values in a computer. In this way, type and distribution of tissue in the object is determined. The stored calibrated datas is provided by expert evaluation of a sufficiently great number of samples of crabs. The evaluation is done by opening the crabs after they have first been photographed and boiled.

The basis of the analysis of the images is that different substances which can be contained in the crab permit the escape of light of different wavelengths at different rates. The transmission ability of organic tissue mainly increases with increasingwavelengths, while the transmission ability of water is decreases. In Fig. 2 there is shown a drawing of a crab where interesting measuring regions are marked. The crab meat is most evident in regions 11. When the meat extends all the way out to the edges 17 of the shell, this is a sign that the crab is of good quality. In cases where this is a particularily high degree of filling, the breathing spaces 13 can also be partly filled. When the so called stomach 14 is of large size, which is not eatable, this is a sign of a low degree of filling. The mid region of the crab contains the so called cage 15. The roe of the female crab is situated around the cage and in the regions 11. The sex of the crab is determined in the area 16.

The brown meat 12, also called the liver, is well visible and is measured for size and density. The lighter the brown meat is, the higher the quality. For female crabs areas 15 and 11 are measured for roe. Measurements should further be conducted in the edge area of the meat 17, and in the breathing spaces 13. If the brown meat 12 is chipped, this is a sign of the crab being poorly filled. Both the brown meat 12 and eggs in female crabs in the areas 15 org 11 have a greater absorption than the rest of the tissue.

On the basis of the above mentioned, an analysis can be conducted to determine the "filling grade" (content of food) of a crab. Determining the sex is done on the basis of the shape of the crab shell. The final quality determination is done by comparing the distribution of light absorbing tissue with distribution in the preclassified calibrated samples.

The crab is classified in a predetermined number of quality classes which are determined through the preclassifying calibrating samples. When the computer has performed the final determination, an output of the computer may give a signal which indicates the determined class. This signal can be used for controlling an automat for transporting the crab from the glass plate to a collection site for this quality.

The method may also be used in connection with different measurements of the food content of crabs. In principle, it can be used in all materials where an invasive examination or analysis is not possible. What is specially discovered by using this method, is water against other materials, mainly organic tissue. But other kinds of substances having different absorption abilities can also be stated. It is necessary that the object has a certain transparency for visible and infrared light.

Claims

1. Method for determining the kind and distribution of tissue in living organisms (1), especially the food content in e.g. crabs, where the organism (1) is situated between a light source (2) for visible and infrared light, and a camera (3) connected to a computer (4), the organism (1) is candled by the visible and infrared light, the camera (3) registers this candeling, and the result is analysed by the computer (4), characterized by the camera (3) shoots a plane image of the object in one or more wavelength range, data derived from the image or the images is analysed, by in particular, comparing data descriptive of regions of the registered images, to corresponding data from images of corresponding objects of known quality, whereby the objects are sorted into predetermined quality classes.

2. Method according to claim 1, characterized by the measurements are being performed in one or more bands in this spectral range of 400 - 2000nm.

3. Method according to claim 1 or 2, characterized by the organism (1) being situated on a transparent medium (6).

4. Method according to claim 3, characterized by the transparent medium being a dim glass plate.

5. Method according to claim 3, characterized by the transparent medium being a clear glass plate.

6. Method according to claim 3, characterized by the transparent basis being a non-refracting and non-reflacting grid.

7. Method according to claim 6, characterized by the grid being arranged to be moveable as a conveyer, to transport the organism (1) relative to the camera (3).

8. Method according to any one of claims 1-7, characterized by a spreading unit (7) being arranged between the light source (2) and the transparent medium (6), preferably a defocus collimator (7) or a spreading lens.

9. Method according to any one of claims 1-8, characterized by the relation between an aperture (22) for the light source (2), the size of the object, and the camera's (3) lens being arranged so that the aperture (22) can not be seen from the camera (3).

10. Method according to any one of claims 1-9, characterized by a grey reference (8) being situated in the vicinity of the organism (1), and that this grey reference (8) is included in the picture to be analysed by the computer (4).

11. Method according to any one of claims 1-10 characterized by a light trap (24) being situated as a background for the object (1) seen from the camera (3).

12. Method according to any on of claims 1-11, characterized by the camera (3) being situated in a container (31) which absorbs so much of the incomming light that the reflected light does not contribute substantially to illumination of the object.