A METHOD OF AREA LOCALIZATION OF MEAT, IN PARTICULAR FISH, WHICH IS INITIALLY SUBJECTED TO ILLUMINATION

Abstract: A method of area localization of a piece of meat, in particular fish, which is initially subjected to illumination. To perform automated localization of the exact position of various occurrences as well as meat texture, the piece of meat is illuminated in a predetermined patterm to provide contour information, which is recorded in a direction different from the illumination direction, said contour information being then used for providing additional information on the nature and the exact position of occurrences within the contour of the piece of meat.

Description: A method of area localization of meat, in particular fish, which is initially subjected to illumination The invention concerns a method of area localization of meat, in particular fish, which is initially sub- jected to illumination. Various illumination techniques are known in connec¬ tion with determination of the quality of meat pro¬ ducts, where illumination of such meat products-by means of a special device provides contour information on the surface nature of the products, or so-called texture, via contrast occurrences, where localization proper of defects can e.g. be performed by means of a UV recording in another optical system. These previous techniques have thus been based on exa- mination and control measures concerning meat fillets in particular of a boneless type. The techniques have therefore not been able to ensure to a sufficient de¬ gree that the sliced fillets have been completely free of bone occurrences while maintaining an optimum meat amount, so these known techniques are not suitable for the special localization accuracy which is required in connection with correct boning and removal of im¬ purities and the like. Alternatively, both image recordings might be provided in a combined system, the fillet being initially irradi¬ ated with infrared and/or visible light in connection with being irradiated with ultra-violet light. The image thus produced therefore gives information on both the surface characteristics and the occurrences. The object of the invention is to provide a method wherein it is possible, in determined areas of in par- ticular fish, to perform automatic localization of the exact position of occurrences, such as e.g. bones, im¬ purities, fins, as well as optionally the texture in general, and so that the fillets can subsequently be subjected to very careful, automated processing optionally in the form of cutting and slicing in the areas in ques¬ tion. With further boning it is thus possible to obtain a completely clean and boneless fillet in this manner while maintaining the greatest possible amount of meat. This object is obtained by a method where a fish-fillet is initially subjected to illumination in a predetermined pattern, which provides a segmented surface characteristic of the fillet. The light characteristic thus produced, when recording an image in a direction different from the illumination direction, produces unambiguous infor¬ mation on the contour variations of the object, but also on the nature of the texture. This contour information entails that subsequently the detection of undesirable occurrences can be concentrated to the characteristic sub-areas of the object produced via the illumination. The resulting additional information is then used for focusing of the object on areas in which the occurrences are disposed. In the sub-areas thus encircled, it is now possible to locate the shape and type of the fillet and to localize the thick and thin areas, the bones, impurities and texture in general of the fillet, via contrast formations in the contour information. The actual detection of various occurrences in or on the fillet may advantageously be provided by means of the sequence of the contour lines, e.g. angular measure¬ ments of curve tangents to the fish contour so that areas having determined curve shapes are used for indi- eating the location of various impurities, it being possible to perform calculations of this type for each light beam in the transverse direction of the f.ish. This is stated in claim 2. In connection with additional strengthening of the area localization it is possible to combine the con¬ tour information provided via the initial illumination with statistical data for the fish type in question. These statistical data give the system instructions concerning the approximate location of the characte¬ ristic sub-areas, known by experience, of the individual type of fish. It will thus be appreciated that the use of statistical data for preceding definition of the characteristic areas of the fish will have importance in connection with the processing accuracy and speed obtainable in a fish cleaning plant, where said methods are used in connection with subsequent stations for cutting, slicing and boning. This is stated in claim 3. When the additional information provided on the ' basis of the contour information modifies the search of con¬ tour information away from the trivial areas so that this is increased in the given, characteristic areas, knowledge on the characteristic sub-areas is obtained more rapidly and with greater certainty where even occurrences insignificant in terms of area, so-called ray bones and black membranes, can be detected. These occurrences are extremely difficult to distinguish without a relatively careful search of the contour information. As will be appreciated from the foregoing, the method of the invention is based on the wish for a completely automated processing line, where treatment stations for the actual boning are already performed mechanically today, while the so-called trimming, for which the area localization of the invention forms the ground¬ work, takes place manually. Of course, this involves a relatively great consumption of time, and moreover not all undesirable occurrences are localized and re¬ moved with certainty. The invention will be explained more fully below with reference to the drawing, in which figs. 1 and 2 are a top view and a side view, respective¬ ly, of a fish fillet, fig. 3 is a cross-sectional view of the fish fillet illustrated in figs. 1 and 2, from which it appears how the fish fillet is subjected to illumination and image recording, and fig. 4 shows the contour information of an illuminated fish fillet. Figs. 1-3 show an example of a fish fillet 1 and are to illustrate how such a fillet may have an irregular surface extent and rim contour, of which in particular fig. 3 shows how the meat thickness may vary over the fish fillet. It will be appreciated that for various types of fish close connection exists between the meat occurrences, i.e. thickness, surface extent, location of bones, fins, impurities and other matter. Fig. 3 also shows how in a first step of the detection process the fish fillet is subjected to illumination which is here provided in the form of a plurality of arranged lines of light transversely to the longitudi- nal direction of the fillet. The illumination is here made by means of a light source 2 which emits light directed obliquely to the supporting plane of the fillet, which, after illumination, is subjected to image record¬ ing with a camera 3 placed perpendicularly above the fillet. It will be appreciated that when recording an image in a direction different from the direction of illumination, the streaks of light will display a surface contour of the fillet showing its thick and thin areas, etc. This contour information appears from fig. 4. The resulting graph drawing will thus immediately segment the fish fillet so as to provide knowledge on the special nature of the fillet and thus knowledge on characteristic sub-areas. This contour information thus forms the basis for the actual search of the various occurrences of the fillet, which may be provided by various techniques. Of course, various types of fish have various locations of occur¬ rences of a more or less undesirable nature, it being appreciated that this advance knowledge about such circumstances can advantageously be utilized in the form of a sort of statistical data for the fish ' type in question. These statistical data can therefore be added to the system in the form of instructions con¬ cerning the location of the characteristic sub-areas, known by experience, of the individual type of fish, and these instructions may be combined with the actual search on the basis of the above-mentioned graph drawing. Accordingly, this additional information may be used for controlling the search of contour information to- wards the areas where impurities probably occur. It will therefore be appreciated that the use of these statistical data for preceding definition of the charac¬ teristic area of the fish in combination with the contour information will have importance in connection with the processing accuracy and speed which can be obtained in a fish cleaning plant. The actual search can there¬ fore be established by means of the angular measurements between curve tangents to the fish contour (see fig. 3 ) mentioned initially, where the areas with determined angular relations indicate that e.g. a fish bone is present in the area immediately below these. The information gathered hereby gives a set of data for the further processing of the fillet in subsequent stations so as to ensure correct cutting amounts, sliced lengths and sequence of slicing for the sub-areas of the individual fish. It is obtained in this manner that the fish fillets are examined and processed indi¬ vidually, thereby improving the overall product quality in a fish cleaning plant significantly.

Claims: P a t e n t C l a i m s 1. A method of area localization of a piece of meat, in particular fish, and comprising illumination of the piece of meat, c h a r a c t e r i z e d by performing the illumination with a source of light adapted to pro¬ duce a predetermined pattern, preferably consisting of lines, on a plane face, and recording an image of the light pattern formed on the piece of meat in.-a di¬ rection different from the illumination direction to provide light information which is then used for pro¬ ducing additional information on the nature and the exact location of occurrences within the contour of the piece of meat. 2. A method according to claim 1, c h a r a c t e r - i z e d by providing the additional information on the basis of angular relations between a plurality of tangents to a curve which represent the contour of the fish at a given point. 3. A method according to claims 1 and 2, c h a f a c - t e r i z e d by adding statistical data for the fish type in question for definition of its characteristic areas to improve the basis for the provision of the additional information. 4. A method according to claim 1, c h a r a c t e r - i z e d by using the additional information provided on the basis of the contour information for controlling the search of an item of contour information away from the trivial areas so that said search is increased in the given, characteristic areas.

Inventors: HAAGENSEN PETER, HAAGENSEN, PETER
Applicants: LUMETECH AS, LUMETECH A/S
Application year: 1989
Main classification: A22C25
IPC codes: A22C17, A22C25