Method and apparatus for automatically optimizing optical contrast in automated equipment
View Patent ↗Techniques for automatically adjusting and/or optimizing the color and/or intensity of the illuminating light used in a vision system is presented. The intensity of each of a plurality of illuminating light colors is allowed to be independently adjusted to adapt the illumination light based on the color of a part feature against the part feature background of a part being viewed by the vision system to produce high contrast between the part feature and background. Automated contrast optimization may be achieved by stepping through all available color combinations and evaluating the contrast between the part feature and background to select a color combination having a “best” or acceptable contrast level. Alternatively, contrast optimization may be achieved by performing a “smart” search in which a high contrast coarse illumination light is first selected, and then all available color combinations within range of the selected coarse illumination color are stepped through to select a fine illumination color resulting in optimal contrast.
1. An electronic vision system, comprising:
an illumination light generator capable of generating illumination light of a plurality of different illumination light colors and/or intensities and which illuminates a part feature against a part feature background;
a camera which images the part feature against the part feature background;
a contrast tester which measures a contrast level between said part feature and said part feature background; and
an illumination system controller which is responsive to the contrast level and to acceptable contrast criteria to adjust the illumination light generator to illuminate the part feature against the part feature background to one of the plurality of different illumination light colors and/or intensities such that the contrast level meets the acceptable contrast criteria, wherein the illumination system controller steps through a set of available coarse illumination colors and then steps through a set of available fine illumination colors within a predetermined range of the coarse illumination colors resulting in a highest contrast level.
2. An electronic vision system in accordance with claim 1 , wherein the illumination system controller adjusts the illumination light generator to illuminate the part feature against the part feature background by:
selecting one of the plurality of different illumination light colors and/or intensities;
controlling the illumination light generator to illuminate the part feature against the part feature background with the selected illumination light color and/or intensity;
measuring a contrast level corresponding to the selected illumination light color and/or intensity between the part feature and the part feature background;
determining whether the contrast level corresponding to the selected illumination light color and/or intensity meets the acceptable contrast criteria; and
repeating the selecting step through the determining step if the contrast level corresponding to the selected illumination light color and/or intensity does not meet the acceptable contrast criteria.
3. An electronic vision system in accordance with claim 2 , wherein the selected illumination light color and/or intensity comprises one of the plurality of different illumination light colors and/or intensities resulting in a highest contrast level.
4. An electronic vision system in accordance with claim 3 , wherein the illumination system controller steps through the set of available coarse illumination colors and selects one of said available coarse illumination colors which meets said acceptable contrast criteria, and then steps through the set of available fine illumination colors within a predetermined range of said selected coarse illumination color and selects one of said available fine illumination colors resulting in a highest contrast level.
5. An electronic vision system in accordance with claim 1 , wherein the illumination light generator comprises a plurality of LEDs each of which is independently controlled by the illumination system controller.
6. An electronic vision system in accordance with claim 1 , wherein said illumination light generator comprises:
a plurality of light-emitting diodes (LEDs) each configured to operate in a plurality of illumination states.
7. An electronic vision system in accordance with claim 6 , wherein said plurality of LEDs comprise at least two colors of LEDs.
8. An electronic vision system in accordance with claim 6 , wherein said plurality of LEDs comprise red, green, and blue LEDs.
9. A method for automatically adapting illumination light in a vision system to a color of a part feature against a part feature background of a part being viewed by said vision system, comprising:
selecting at least one of group consisting of a coarse and fine illumination color from a set of available coarse and fine illumination colors;
setting said illumination light in said vision system to said selected illumination color;
measuring a contrast level corresponding to the selected illumination color between said part feature and said part feature background;
determining whether said measured contrast level corresponding to the selected illumination color meets acceptable contrast criteria; and
repeating said selecting step through said determining step if said measured contrast level corresponding to the selected illumination color does not meet said acceptable contrast criteria.
10. The method of claim 9 , further comprising:
repeating said selecting step through said determining step until a contrast level corresponding to each illumination color in the set of available illumination colors is obtained;
setting the illumination light to the illumination color in the set of available illumination colors having a highest corresponding contrast level.
11. A computer readable storage medium tangibly embodying computer program instructions for automatically adapting illumination light in a vision system to a color of a part feature against a part feature background of a part being viewed by said vision system, comprising the instructions of:
selecting at least one of group consisting of a coarse and fine illumination color from a set of available illumination colors;
setting said illumination light in said vision system to said selected illumination color;
measuring a contrast level corresponding to the selected illumination color between said part feature and said part feature background;
determining whether said measured contrast level corresponding to the selected illumination color meets acceptable contrast criteria; and
repeating said selecting step through said determining step if said measured contrast level corresponding to the selected illumination color does not meet said acceptable contrast criteria.
12. The computer readable storage medium of claim 11 , further comprising the instructions of:
repeating said selecting step through said determining step until a contrast level corresponding to each illumination color in the set of available illumination colors is obtained;
setting the illumination light to the illumination color in the set of available illumination colors having a highest corresponding contrast level.
13. An electronic vision system, comprising:
an illumination light generator capable of generating illumination light of a plurality of different illumination light colors and/or intensities and which illuminates a part feature against a part feature background;
a camera which images the part feature against the part feature background;
a contrast tester which measures a contrast level between said part feature and said part feature background; and
an illumination system controller which is responsive to the contrast level and to acceptable contrast criteria to adjust the illumination light generator to illuminate the part feature against the part feature background to one of the plurality of different illumination light colors and/or intensities such that the contrast level meets the acceptable contrast criteria, by at least selecting one of the plurality of different illumination light colors and/or intensities,
wherein the illumination system controller steps through a set of available coarse illumination colors and selects one of the available coarse illumination colors which meets the acceptable contrast criteria, and then steps through a set of available fine illumination colors within a predetermined range of the selected coarse illumination color and selects one of the available fine illumination colors resulting in a highest contrast level.
14. An electronic vision system in accordance with claim 13 , wherein the illumination system controller adjusts the illumination light generator to illuminate the part feature against the part feature background by:
controlling the illumination light generator to illuminate the part feature against the part feature background with the selected illumination light color and/or intensity;
measuring a contrast level corresponding to the selected illumination light color and/or intensity between the part feature and the part feature background;
determining whether the contrast level corresponding to the selected illumination light color and/or intensity meets the acceptable contrast criteria; and
repeating the selecting step through the determining step if the contrast level corresponding to the selected illumination light color and/or intensity does not meet the acceptable contrast criteria.
15. An electronic vision system in accordance with claim 14 , wherein the selected illumination light color and/or intensity comprises one of the plurality of different illumination light colors and/or intensities resulting in a highest contrast level.
16. An electronic vision system in accordance with claim 13 , wherein the illumination light generator comprises a plurality of LEDs each of which is independently controlled by the illumination system controller.
17. An electronic vision system in accordance with claim 13 , wherein said illumination generator comprises:
a plurality of light-emitting diodes (LEDs) each configured to operate in a plurality of illumination states.
18. An electronic vision system in accordance with claim 17 , wherein said plurality of LEDs comprise at least two colors of LEDs.
19. An electronic vision system in accordance with claim 17 , wherein said plurality of LEDs comprise red, green, and blue LEDs.
20. An electronic vision system, comprising:
an illumination light generator capable of generating illumination light of a plurality of different illumination light colors and/or intensities and which illuminates a part feature against a part feature background;
a camera which images the part feature against the part feature background;
a contrast tester which measures a contrast level between said part feature and said part feature background; and
an illumination system controller which is responsive to the contrast level and to acceptable contrast criteria to adjust the illumination light generator to illuminate the part feature against the part feature background to one of the plurality of different illumination light colors and/or intensities such that the contrast level meets the acceptable contrast criteria, wherein the illumination system controller adjusts the illumination light generator to illuminate the part feature against the part feature background by:
selecting one of the plurality of different illumination light colors and/or intensities comprising the illumination system controller stepping through a set of available coarse illumination colors and selecting one of the available coarse illumination colors which meets the acceptable contrast criteria, and then stepping through a set of available fine illumination colors within a predetermined range of the selected coarse illumination color and selecting one of the available fine illumination colors;
controlling the illumination light generator to illuminate the part feature against the part feature background with the selected illumination light color and/or intensity;
measuring a contrast level corresponding to the selected illumination light color and/or intensity between the part feature and the part feature background;
determining whether the contrast level corresponding to the selected illumination light color and/or intensity meets the acceptable contrast criteria; and
repeating the selecting step through the determining step if the contrast level corresponding to the selected illumination light color and/or intensity does not meet the acceptable contrast criteria.