System and method for reading direct part marking (DPM) codes on objects
A system and method of inspection may include capturing image data by a stereo imaging device. A determination as to whether noise indicative of a transparent or specular object exists in the image data may be made. A report that a transparent or specular object was captured in the image data may be made.
1. A method of inspection, comprising:
capturing stereo image data inclusive of a direct part marking (DPM) code on an object;
rectifying the captured stereo image data to produce rectified image data from the captured stereo image data;
generating a depth map inclusive of the DPM code from the rectified image data; and
reading the DPM code from the depth map.
2. The method according to claim 1 , further comprising applying the captured stereo image data to a stereo matching map to cause a pair of images of the captured stereo image data to be in a common map coordinate system.
3. The method according to claim 1 , wherein rectifying the captured stereo image data includes rectifying the captured stereo image data to produce rectified image data that is 2D data representative of a 3D image.
4. The method according to claim 1 , wherein capturing stereo image data includes capturing stereo image data using a pair of linear cameras.
5. The method according to claim 4 , wherein capturing stereo image data includes capturing stereo image data inclusive of color spectrum information.
6. The method according to claim 1 , wherein capturing stereo image data includes capturing stereo image data using a pair of two-dimensional (2D) image sensors.
7. The method according to claim 1 , further comprising configuring an illumination device to illuminate the DPM code on the object.
8. The method according to claim 7 , wherein configuring the illumination device includes configuring an LED illumination device.
9. The method according to claim 8 ,
wherein configuring an illumination device includes configuring an illumination device capable of selectably illuminating in one wavelength from a plurality of selectable wavelengths; and
controlling the illumination device to a selected wavelength.
10. The method according to claim 9 , further comprising:
selecting a first selectable wavelength of the illumination device to illuminate the DPM code;
causing the stereo imaging device to image the DPM code illuminated with the first wavelength;
selecting a second selectable wavelength of the illumination device to illuminate the DPM code;
causing the stereo imaging device to image the DPM code illuminated with the second wavelength; and
selecting which of the first wavelength or second wavelength causes the DPM code to result in a depth map with higher contrast.
11. The method according to claim 1 , further comprising automatically determining information content of the DPM code.
12. The method according to claim 11 , further comprising using color information of the object in automatically determining the alphanumeric values.
13. An inspection system, comprising:
a stereo imaging device configured to capture stereo image data inclusive of a direct part marking (DPM) code on an object; and
a processing unit in communication with said stereo imaging device, and configured to:
rectify the captured stereo image data to produce rectified image data from the captured stereo image data;
generate a depth map inclusive of the DPM code from the rectified image data; and
read the DPM code from the depth map.
14. The inspection system according to claim 13 , wherein said processing unit is further configured to apply the captured stereo image data to a stereo matching map to cause a pair of images of the captured stereo image data to be in a common map coordinate system.
15. The inspection system according to claim 13 , wherein the rectified image data is 2D data representative of a 3D image.
16. The inspection system according to claim 13 , wherein the stereo imaging device includes a pair of linear cameras.
17. The inspection system according to claim 16 , wherein the pair of linear cameras are color linear cameras.
18. The inspection system according to claim 13 , wherein the stereo imaging device includes a pair of two-dimensional (2D) image sensors.
19. The inspection system according to claim 13 , further comprising an illumination device configured to illuminate the DPM code on the object.
20. The inspection system according to claim 19 , wherein the illumination device is an LED illumination device.
21. The inspection system according to claim 19 , wherein the illumination device is configured to selectably illuminate in one wavelength from a plurality of selectable wavelengths.
22. The inspection system according to claim 19 , wherein said processing unit is further configured to:
select a first selectable wavelength of the illumination device to illuminate the DPM code;
cause said stereo imaging device to image the DPM code illuminated with the first wavelength;
select a second selectable wavelength of the illumination device to illuminate the DPM code;
cause said stereo imaging device to image the DPM code illuminated with the second wavelength; and
select which of the first wavelength or second wavelength causes the DPM code to result in a depth map with higher contrast.
23. The inspection system according to claim 13 , wherein said processing unit is further configured to automatically determine information content of the DPM code.
24. The inspection system according to claim 23 , wherein said processing unit is further configured to use color information of the object in automatically determining the alphanumeric values.