Evaluating features in an image possibly corresponding to an intersection of a pallet stringer and a pallet board

• US 8,934,672 B2
• Filed: 10/16/2012
• Issued: 01/13/2015
• Est. Priority Date: 10/19/2011
• Status: Active Grant

• Current Assignee: Crown Equipment Corporation
• Original Assignee: Crown Equipment Corporation
• Inventors: Holeva, Lee F., Elston, Edwin R., Jensen, Eric L., Seelinger, Michael J., Yoder, John-David S.
• Primary Examiner(s): NAKHJAVAN, SHERVIN K
• Application Number:
  US13/652,510
• Publication Number:
  US 20130101166A1
• Time in Patent Office: 819 Days
• Field of Search: None
• US Class Current: 382/103
• CPC Class Codes: B66F 9/122 longitudinally movable
• CPC Class Codes: B66F 9/24 Electrical devices or systems
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 7/13 Edge detection
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51

Abstract

A programmable computer-implemented method is provided for finding possible corners of a pallet in an image. The method may comprise: acquiring a grey scale image including one or more pallets; determining, using a computer, horizontal cross correlations between the image and a first step-edge template to generate a set of horizontal cross correlation results; determining, using the computer, vertical cross correlations between the image and a second step-edge template to generate a set of vertical cross correlation results; and determining, using the computer, a first set of pixels, each such pixel respectively corresponding to a possible first corner of the one or more pallets, using a first corner template, the set of horizontal cross correlation results and the set of vertical cross correlation results.

Claims

1. A programmable computer-implemented method for finding possible corners of a pallet in an image comprising:

acquiring a grey scale image including one or more pallets;

determining, using a computer, horizontal cross correlations between the image and a first step-edge template to generate a set of horizontal cross correlation results;

determining, using said computer, vertical cross correlations between the image and a second step-edge template to generate a set of vertical cross correlation results; and

determining, using said computer, a first set of pixels, each such pixel respectively corresponding to a possible first corner of the one or more pallets, using a first corner template, the set of horizontal cross correlation results and the set of vertical cross correlation results.

2. The method of claim 1, further comprising:

comparing, using said computer, each pixel in the first set of pixels to a first threshold value and generating a second set of pixels corresponding to a second set of possible first corners based on the comparison between the first threshold value and each pixel in the first set; and

sliding, using said computer, a local maxima-locating window over the second set of pixels and eliminating all pixels from the second set of pixels in each placement of the window except for the pixel having a maximum value such that a third set of pixels corresponding to a third set of possible first corners are defined.

3. The method of claim 2, wherein generating the second set of pixels further comprises comparing each pixel in the first set of pixels to the first threshold value and eliminating pixels that are less than the first threshold value so as to generate the second set of pixels.

4. The method of claim 1, further comprising:

determining, using said computer, a fourth set of pixels, each such pixel respectively corresponding to a possible second corner of the one or more pallets using a second corner template, the set of horizontal cross correlation results and the set of vertical cross correlation results;

comparing, using said computer, each pixel in the fourth set of pixels to a second threshold value and generating a fifth set of pixels corresponding to a second set of possible second corners based on the comparison of the second threshold value and each pixel in the fourth set; and

sliding, using said computer, a local maxima-locating window over the fifth set of pixels and eliminating all pixels from the fifth set of pixels in each placement of the window except for the pixel having a maximum value such that a sixth set of pixels corresponding to a third set of possible second corners are defined.

5. The method of claim 4, wherein generating the fifth set of pixels further comprises comparing each pixel in the fourth set to the second threshold value and eliminating pixels that are less than the second threshold value so as to generate the fifth set of pixels.

6. The method of claim 4, wherein said second corner template is defined by an S×

T window and said determining a fourth set of pixels comprises;

generating a second corner image having the fourth set of pixels by sliding the second corner template window concurrently over the set of horizontal cross correlation results and the set of vertical cross correlation results wherein;

during each placement of the second corner template window as it slides concurrently over the horizontal and vertical cross correlation results, receiving along one predefined inner vertical column of the window one or more corresponding horizontal cross correlation results, negating those received horizontal cross correlation results, receiving along one predefined outside horizontal row of the window one or more corresponding vertical cross correlation results, identifying the minimum value of the cross correlation results in the one predefined vertical column and the one predefined horizontal row, and assigning the identified minimum value as a respective value in the fourth set of pixels.

7. The method of claim 1, wherein the first corner template is defined by an M×

N window and said determining the first set of pixels comprises;

generating a first corner image having the first set of pixels by sliding the first corner template window concurrently over the set of horizontal cross correlation results and the set of vertical cross correlation results.

8. The method of claim 7, wherein determining the first set of pixels comprises:

during each placement of the first corner template window as it slides concurrently over the horizontal and vertical cross correlation results, receiving along one predefined vertical column of the window one or more corresponding horizontal cross correlation results, receiving along one predefined horizontal row of the window one or more corresponding vertical cross correlation results, identifying the minimum value of the cross correlation results in the one predefined vertical column and the one predefined horizontal row, and assigning the identified minimum value as a respective value in the first set of pixels.

9. The method of claim 8, wherein said one predefined vertical column comprises one outside vertical column and said one predefined horizontal row comprises one outside horizontal row.

10. The method of claim 8, wherein said assigning the identified minimum value comprises assigning the identified minimum value to the pixel of the first corner image which is located at a position corresponding to an intersection of the one predefined vertical column and the one predefined horizontal row.

11. A system for finding possible corners of a pallet in an image comprising:

an image acquisition component configured to acquire a grey scale image including one or more pallets;

a computer configured to determine horizontal cross correlations between the image and a first step-edge template to generate a set of horizontal cross correlation results;

said computer further configured to determine vertical cross correlations between the image and a second step-edge template to generate a set of vertical cross correlation results; and

said computer further configured to determine a first set of pixels, each such pixel respectively corresponding to a possible first corner of the one or more pallets using a first corner template, the set of horizontal cross correlation results and the set of vertical cross correlation results.

12. The system of claim 11, wherein:

said computer is further configured to compare each pixel in the first set of pixels to a first threshold value and to generate a second set of pixels corresponding to a second set of possible first corners based on the comparison between the first threshold value and each pixel in the first set; and

said computer is further configured to slide a local maxima-locating window over the second set of pixels and to eliminate all pixels from the second set of pixels in each placement of the window except for the pixel having a maximum value such that a third set of pixels corresponding to a third set of possible first corners are defined.

13. The system of claim 12, wherein to generate the second set of pixels said computer is further configured to compare each pixel in the first set of pixels to the first threshold value and eliminate pixels that are less than the first threshold value so as to generate the second set of pixels.

14. The system of claim 11, wherein said computer is further configured to:

determine a fourth set of pixels, each such pixel respectively corresponding to a possible second corner of the one or more pallets, using a second corner template, the set of horizontal cross correlation results and the set of vertical cross correlation results;

compare each pixel in the fourth set of pixels to a second threshold value and generate a fifth set of pixels corresponding to a second set of possible second corners based on the comparison of the second threshold value and each pixel in the fourth set; and

slide a local maxima-locating window over the fifth set of pixels and eliminate all pixels from the fifth set of pixels in each placement of the window except for the pixel having a maximum value such that a sixth set of pixels corresponding to a third set of possible second corners are defined.

15. The system of claim 14, wherein to generate the fifth set of pixels said computer is further configured to compare each pixel in the fourth set to the second threshold value and eliminate pixels that are less than the second threshold value so as to generate the fifth set of pixels.

16. The system of claim 14, wherein said second corner template is defined by an S×

T window and to determine said first set of pixels said computer is further configured to;

generate a second corner image having the fourth set of pixels by sliding the second corner template window concurrently over the set of horizontal cross correlation results and the set of vertical cross correlation results,

wherein during each placement of the second corner template window as it slides concurrently over the horizontal and vertical cross correlation results, said computer is configured to;

receive along one predefined inner vertical column of the window one or more corresponding horizontal cross correlation results,

negate those received horizontal cross correlation results,

receive along one predefined outside horizontal row of the window one or more corresponding vertical cross correlation results,

identify the minimum value of the cross correlation results in the one predefined vertical column and the one predefined horizontal row; and

assigning the identified minimum value as a respective value in the fourth set of pixels.

17. The system of claim 11, wherein the first corner template is defined by an M×

N window and to determine said first set of pixels said computer is further configured to;

generate a first corner image having the first set of pixels by sliding the first corner template window concurrently over the set of horizontal cross correlation results and the set of vertical cross correlation results.

18. The system of claim 17, wherein

during each placement of the first corner template window as it slides concurrently over the horizontal and vertical cross correlation results, said computer is further configured to:

receive along one predefined vertical column of the window one or more corresponding horizontal cross correlation results,

receive along one predefined horizontal row of the window one or more corresponding vertical cross correlation results,

identify the minimum value of the cross correlation results in the one predefined vertical column and the one predefined horizontal row; and

assign the identified minimum value as a respective value in the first set of pixels.

19. The system of claim 18, wherein said one predefined vertical column comprises one outside vertical column and said one predefined horizontal row comprises one outside horizontal row.

20. The system of claim 18, wherein said computer is configured to assign the identified minimum value to the pixel of the first corner image which is located at a position corresponding to an intersection of the one vertical column and the one horizontal row.

21. A computer program product for finding possible corners of a pallet in an image, comprising:

a non-transitory computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising;

computer readable program code configured to acquire a grey scale image including one or more pallets;

computer readable program code configured to determine horizontal cross correlations between the image and a first step-edge template to generate a set of horizontal cross correlation results;

computer readable program code configured to determine vertical cross correlations between the image and a second step-edge template to generate a set of vertical cross correlation results;

computer readable program code configured to determine a first set of pixels, each such pixel respectively corresponding to a possible first corner of the one or more pallets, using a first corner template, the set of horizontal cross correlation results and the set of vertical cross correlation results.

22. The computer program product of claim 21, further comprising:

computer readable program code configured to compare each pixel in the first set of pixels to a first threshold value and generating a second set of pixels corresponding to a second set of possible first corners based on the comparison between the first threshold value and each pixel in the first set; and

computer readable program code configured to slide a local maxima-locating window over the second set of pixels and eliminating all pixels from the second set of pixels in each placement of the window except for the pixel having a maximum value such that a third set of pixels corresponding to a third set of possible first corners are defined.

23. The computer program product of claim 22, further comprising:

computer readable program code configured to compare each pixel in the first set of pixels to the first threshold value and eliminate pixels that are less than the first threshold value so as to generate the second set of pixels.

24. The computer program product of claim 21, further comprising:

computer readable program code configured to determine a fourth set of pixels, each such pixel respectively corresponding to a possible second corner of the one or more pallets using a second corner template, the set of horizontal cross correlation results and the set of vertical cross correlation results;

computer readable program code configured to compare each pixel in the fourth set of pixels to a second threshold value and generating a fifth set of pixels corresponding to a second set of possible second corners based on the comparison of the second threshold value and each pixel in the fourth set; and

computer readable program code configured to slide a local maxima-locating window over the fifth set of pixels and eliminate all pixels from the fifth set of pixels in each placement of the window except for the pixel having a maximum value such that a sixth set of pixels corresponding to a third set of possible second corners are defined.

25. The computer program product of claim 24, further comprising:

computer readable program code configured to compare each pixel in the fourth set to the second threshold value and eliminate pixels that are less than the second threshold value so as to generate the fifth set of pixels.

26. The computer program product of claim 24, wherein said second corner template is defined by an S×

T window, and further comprising;

computer readable program code configured to generate a second corner image having the fourth set of pixels by sliding the second corner template window concurrently over the set of horizontal cross correlation results and the set of vertical cross correlation results; and

computer readable program code configured to, during each placement of the second corner template window as it slides concurrently over the horizontal and vertical cross correlation results, receive along one predefined inner vertical column of the window one or more corresponding horizontal cross correlation results, negate those received horizontal cross correlation results, receive along one predefined outside horizontal row of the window one or more corresponding vertical cross correlation results, identify the minimum value of the cross correlation results in the one predefined vertical column and the one predefined horizontal row, and assign the identified minimum value as a respective value in the fourth set of pixels.

27. The computer program product of claim 21, wherein the first corner template is defined by an M×

N window, and comprising;

computer readable program code configured to generate a first corner image having the first set of pixels by sliding the first corner template window concurrently over the set of horizontal cross correlation results and the set of vertical cross correlation results.

28. The computer program product of claim 27, further comprising:

computer readable program code configured to, during each placement of the first corner template window as it slides concurrently over the horizontal and vertical cross correlation results, receive along one predefined vertical column of the window one or more corresponding horizontal cross correlation results, receive along one predefined horizontal row of the window one or more corresponding vertical cross correlation results, identify the minimum value of the cross correlation results in the one predefined vertical column and the one predefined horizontal row, and assign the identified minimum value as a respective value in the first set of pixels.

29. The computer program product of claim 28, wherein said one predefined vertical column comprises one outside vertical column and said one predefined horizontal row comprises one outside horizontal row.

30. The computer program product of claim 28, further comprising:

computer readable program code configured to assign the identified minimum value to the pixel of the first corner image which is located at a position corresponding to an intersection of the one predefined vertical column and the one predefined horizontal row.