Color sorting system and method

• US 5,085,325 A
• Filed: 09/29/1989
• Issued: 02/04/1992
• Est. Priority Date: 03/08/1988
• Status: Expired due to Term

• Current Assignee: Key Technology, Inc. (Duravant LLC), Simco/Ramic Corporation
• Original Assignee: Simco/Ramic Corporation
• Inventors: Cavin, deceased, Dennis, Coolidge, Arthur W., Betts, Norman L., Jones, Clarence S., Moser, Jeffrey M., McGarvey, Kenneth J.
• Primary Examiner(s): Huppert, Michael S.
• Assistant Examiner(s): WACYRA, EDWARD MICHAEL
• Application Number:
  US07/415,056
• Time in Patent Office: 858 Days
• Field of Search: 209/576, 209/577, 209/580-582, 209/587, 209/939, 364/526, 356/23, 356/402, 356/406, 356/407, 356/425, 382/17
• US Class Current: 209/580
• CPC Class Codes: B07C 5/3422 using video scanning devices, e.g. TV-cameras
• CPC Class Codes: Y10S 209/939 Video scanning

Abstract

Color sorting system and method which are particularly suitable for sorting fruits and vegetables. The objects to be sorted are scanned with a color video camera, and the signals from the camera are digitized and utilized to address a look up table. The look up table is preloaded to provide reject data at those addresses for colors to be rejected. Several techniques for loading the look up table are disclosed. Then, on an online basis, the successive images address the look up table and the reject data is analyzed to drive appropriate reject apparatus. In one embodiment, the data from the look up table is applied to a spatial filter, and objects are rejected only if they have a certain number or sequence of unacceptable colors.

Claims

1. Apparatus for processing moving items having a plurality of color values, comprising:

a look up table with addressable memory locations corresponding to said color values and with an indicating datum stored at each of said locations indicating an item or a portion thereof has acceptable or rejectable color values;

color camera means for capturing an image of said moving items;

normalizing means for providing normalized color values of said image from said color camera means;

addressing means using said normalized color values for addressing said look up table;

color value expanding means for providing around a central color value a range of color values having said indicating datum stored in corresponding look up table locations to compensate for any one of system noise, a range of color variation, or optical variations; and

memory means responsive to said stored datum in said look up table locations corresponding to the captured image of the moving items for storing processing data used to process said moving items.

2. Apparatus as in claim 1 in which said normalizing means includes analog gain adjusting means for normalizing said color values.

3. Apparatus as in claim 1 where said memory means includes a memory matrix with at least the same number of elements as there are in the captured image.

4. Apparatus as in claim 1 where said color camera means includes flash illumination means for effectively stopping the motion of the image of said moving items.

5. Apparatus as in claim 1, including a secondary look up table for off line usage.

6. A method of real time image recognition of moving items having a plurality of color values for processing the items on the basis of color variations, comprising the following steps:

constructing a look up table having memory locations addressable by the color values of items or portions thereof to be processed, where each addressable memory location is stored with a datum indicating an item or a portion thereof has acceptable or rejectable color values;

capturing a color image of said moving items;

normalizing said color values of said captured color image and using said normalized color values to address said look up table;

expanding around a central color value a range of color values having said datum stored in corresponding look up table locations to compensate for any of system noise, a range of color variation, and optical variations; and

reading out said datum from said look up table and determining which items or portions thereof are to be processed based on said acceptable or rejectable values as determined by said datum.

7. A method as in claim 6, where said normalization includes compensating for ambient conditions.

8. A method as in claim 6, where said normalization is also utilized in said step of constructing said look up table.

9. A method as in claim 7 where in said step of constructing said look up table, selected rejectable color values are placed on a color television monitor and blinked at a rate viewable by an observer.

10. A method of analyzing and processing moving items corresponding to images represented by rows of pixels, each pixel having a value, said method comprising the following steps:

capturing one of said images;

normalizing each pixel value of said one of said captured images;

designating pixels within said image, said pixels representing moving items, or portions thereof, and satisfying a criterion for processing said moving items;

expanding around the value of said designated pixels a range of pixel values to compensate for any one of system noise, a range of color variation, or optical variations;

storing a datum within a look up table at look up table locations addressed by said range of pixel values; and

reading out said datum from said look up table locations and determining said processing of moving items or portions thereof, based on said criterion represented by said read out datum.

11. A method as in claim 10, including the step of digitizing each of said pixel values into a number, said number representing an address of said look up table.

12. A method as in claim 10, where said items move at a speed and where said images are taken at a rate dependent on the speed of said moving items and the digitization of the image occurs at a video pixel readout rate.

13. A method as in claim 10 where each pixel is converted into a number representing its color or black and white shade, said digital number representing an address vector for said look up table.

14. A method as in claim 10, where said look up table is constructed from a precalculated set of values derived from a previously measured set of pixel values.

15. A method as in claim 10 where said processing is accomplished by a predetermined algorithm relating to contiguous relationship of pixel data from said look up table.

16. Apparatus for processing moving items in accordance with color, comprising:

means for providing normalized color value signals corresponding to colors on the moving items,

a first look up table having memory locations addressed by the normalized color value signals, each of said addressed locations having a stored datum indicating whether the colors to which the signals correspond are acceptable or not,

a second look up table having addressable memory locations, each of which having accept/reject datum stored therein,

logic means responsive to the output of the first look up table for directly addressing the memory locations of the second look up table, and

means responsive to the addressed accept/reject datum from the second look up table for controlling the processing of the moving items.

17. The apparatus of claim 16 wherein the logic means for directly addressing the memory locations of the second look up table includes means for converting a serial stream of output data from the first look up table to multibit address signals for the second look up table.

18. A method of processing moving items in accordance with color, comprising the steps of:

storing accept/reject datum at addressable locations in first and second look up tables to indicate whether address signals applied to the look up tables represent acceptable colors,

providing normalized color value signals corresponding to colors at a plurality of sites on the moving items,

addressing the first look up table with the normalized color value signals to provide said first look up table datum as output signals which indicate whether the colors at the sites on the moving items are acceptable,

addressing the second look up table in accordance with a group of the output signals to provide said second look up table datum of processing signals which indicate whether the group of output signals is acceptable, and

controlling the processing of the items in accordance with the processing signals.

19. The method of claim 18 wherein the second look up table is addressed by converting a serial stream of output data from the first look up table to a multibit address signal, and applying the multibit address signal to the second look up table.

20. In apparatus for sorting items in accordance with color on a moving conveyor belt:

a. means for providing color value signals corresponding to colors at a plurality of sites on the conveyor belt;

b. a look up table having memory locations addressed by the color value signals;

c. means for loading the memory locations with data indicating whether the colors corresponding to the signals which address the locations are acceptable or not, said means comprising;

(1) means for representing a sample color as a point in a three dimensional coordinate system in which three predetermined colors are plotted along first, second and third mutually perpendicular axes;

(2) means for determining the spherical coordinates r,φ

,Θ

of the sample color, where r is the length of a vector extending from the origin to the point representing the sample color, φ

is the angle between the first axis and the vector, and Θ

is the angle between the second axis and the component of the vector in the plane of the second and third axes;

(3) means for dithering the values of the spherical coordinates to define an ellipsoidal region in the coordinate system representing a range of colors centered generally about the sample color; and

(4) means for storing data in the look up table at memory locations corresponding to the coordinates of points within the ellipsoidal region; and

d. means responsive to data read from the look up table for controlling the course of the items on the conveyor belt.

21. The apparatus of claim 20 wherein the means for storing data in the look up table includes means for comparing the value of r for different points in the coordinate system with r_MIN and r_MAX, where r_MIN and r_MAX are the minimum and maximum values of r in the ellipsoidal region, means for comparing the values of φ

and Θ

for a given point with the minimum and maximum values of φ and

Θ

in the ellipsoidal region if the value of r for the given point is between r_MIN and r_MAX, and means for loading data into a memory location having an address corresponding to the coordinates of the given point if the values of r, φ and

Θ

for the point are between the minimum and maximum values of r, φ and

Θ

in the ellipsoidal region.

22. In a method for sorting items in accordance with color on a moving conveyor belt, the steps of:

a. providing color value signals corresponding to colors at a plurality of sites on the conveyor belt;

b. addressing memory locations in a look up table with the color value signals;

c. loading the memory locations with data indicating whether the colors corresponding to the signals which address the locations are acceptable or not, by the steps of;

(1) representing a sample color as a point in a three dimensional coordinate system in which three predetermined colors are plotted along first, second and third mutually perpendicular axes;

(2) determining the spherical coordinates r,φ

,Θ

of the sample color, where r is the length of a vector extending from the origin to the point representing the sample color, φ

is the angle between the first axis and the vector, and Θ

is the angle between the second axis and the component of the vector in the plane of the second and third axes;

(3) dithering the values of the spherical coordinates to define an ellipsoidal region in the coordinate system representing a range of colors centered generally about the sample color; and

(4) storing data in the look up table at memory locations corresponding to the coordinates of points within the ellipsoidal region; and

d. controlling the course of the items on the conveyor belt in response to data read from the look up table.

23. The method of claim 22 wherein the data is stored in the look up table by comparing the value of r for different points in the coordinate system with r_MIN and r_MAX, where r_MIN and r_MAX are the minimum and maximum values of r in the ellipsoidal region, comparing the values of φ

and Θ

for a given point with the minimum and maximum values of φ and

Θ

in the ellipsoidal region if the value of r for the given point is between r_MIN and r_MAX, and loading data into a memory location having an address corresponding to the coordinates of the given point if the values of r, φ and

Θ

for the point are between the minimum and maximum values of r, φ and

Θ

in the ellipsoidal region.

24. Apparatus for processing moving items in accordance with color on said items, comprising:

a. means for providing normalized color value signals corresponding to colors at a plurality of sites on an acceptable item and at a plurality of sites on an item to be rejected;

b. means responsive to the normalized color value signals for accumulating the number of occurrences of individual colors in the acceptable item and accumulating the number of occurrences of individual colors in the item to be rejected;

c. means for comparing the number of occurrences of the individual colors in the acceptable item with the number of occurrences of the colors in the item to be rejected;

d. a look up table having addressable memory locations corresponding to the colors for storing accept/reject datum corresponding to the relative number of occurrences of the colors in the acceptable item and the number of occurrences of the colors in the item to be rejected;

e. means for addressing the look up table with normalized color value signals corresponding to colors at a plurality of sites on the moving items to read the corresponding accept/reject datum out of the look up table; and

f. means responsive to the accept/reject datum from the look up table for controlling the processing of the items.

25. The apparatus of claim 24 wherein the means for accumulating the number of occurrences of the colors includes a first histogram memory with addressable memory locations corresponding to the colors for storing the number of occurrences of the colors for storing the number of occurrences of the colors in the acceptable item, a second histogram memory with addressable memory locations corresponding to the colors for storing the number of occurrences of the colors on the items to be rejected, and means for incrementing the accumulated number of occurrences in the first histogram memory locations in response to normalized color value signals of acceptable items, and means for incrementing the accumulated number of occurrences in the second histogram memory locations in response to normalized color value signals from items to be rejected.

26. The apparatus of claim 25 wherein the means for comparing the number of occurrences of the colors comprises means for applying address signals to the histogram memories to read the number of occurrences out of the memories, and means for dividing the number of occurrences from one of the memories by the number of occurrences from the other of said memories to provide color occurrence ratios.

27. The apparatus of claim 26 including means for comparing the color occurrence ratios with a threshold level to determine the accept/reject data to be stored in the look up table.

28. A method of processing moving items in accordance with color, comprising the steps of:

a. providing normalized color value signals corresponding to colors at a plurality of sites on an acceptable item and to colors at a plurality of sites on an item to be rejected;

b. accumulating the number of occurrences of individual colors in the acceptable item and accumulating the number of occurrences of individual colors in the item to be rejected in accordance with the normalized color value signals;

c. comparing the number of occurrences of the individual colors in the acceptable item with the number of occurrences of the individual colors in the item to be rejected;

d. storing accept/reject datum corresponding to the relative number of occurrences of the colors in the acceptable item and the number of occurrences of the colors in the item to be rejected in a look up table having addressable memory locations corresponding to the colors;

e. addressing the look up table with normalized color value signals corresponding to colors at a plurality of sites on the moving items to read the accept/reject datum out of the look up table; and

f. controlling the processing of the moving items in accordance with the accept/reject datum from the look up table.

29. The method of claim 28 wherein the number of occurrences of the colors are accumulated by addressing memory locations in a first histogram memory in accordance with the normalized color value signals for the acceptable item, addressing memory locations in a second histogram memory in accordance with the normalized color value signals for the item to be rejected, and incrementing the accumulated number of occurrences in the first histogram memory locations in response to occurrences of the acceptable normalized color value signals and in the second histogram memory locations in response to occurrences of the normalized color value signals for an item to be rejected.

30. The method of claim 29 wherein the number of occurrences of the colors are compared by applying address signals to the histogram memories to read the number of occurrences out of the memories, and dividing the number of occurrences from one of the memories by the number of occurrences from the other of said memories to provide color occurrence ratios.

31. The method of claim 30 including the steps of comparing the color occurrence ratios with a threshold level to determine the accept/reject data to be stored in the look up table.