Robust automatic determination and location of MacBeth color checker charts

• US 9,064,314 B2
• Filed: 03/25/2013
• Issued: 06/23/2015
• Est. Priority Date: 03/25/2013
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Devic, Goran, Gupta, Shalini
• Primary Examiner(s): COUSO, YON JUNG
• Application Number:
  US13/849,817
• Publication Number:
  US 20140286569A1
• Time in Patent Office: 820 Days
• Field of Search: 382/162, 382/165, 382/167, 382/181, 382/190, 358/1.9
• US Class Current: 1/1
• CPC Class Codes: G06T 5/90 Dynamic range modification of images or parts thereof
• CPC Class Codes: G06T 7/73 using feature-based methods
• CPC Class Codes: G06T 7/90 Determination of colour characteristics

Abstract

A MacBeth color checker chart automatic detection system includes an imaging unit that provides an image and a processing unit that applies an edge detection operation to the image and performs a flood-fill operation on the image to provide a flood-filled image. Additionally, the MacBeth color checker chart automatic detection system includes a testing unit that tests the flood-filled image to provide a modified flood-fill image, wherein a set of heuristic tests are employed to automatically determine quantity and location of MacBeth color checker charts. Generally, the set of heuristic tests are employed to automatically reject regions that are unlikely to belong to a MacBeth color checker chart and to cluster the remaining regions that are likely to belong to a Macbeth color checker chart. A MacBeth color checker chart automatic detection method is also provided.

Claims

1. A MacBeth color checker chart automatic detection system, comprising:

a processing computer processor that applies an edge detection operation to an image provided by an imaging unit and performs a flood-fill operation on the image to provide a flood-filled image; and

a testing computer processor that tests the flood-filled image to provide a modified flood-fill image, wherein a set of heuristic tests are employed to automatically determine quantity and location of MacBeth color checker charts.

2. The system as recited in claim 1 wherein the edge detection operation individually identifies edges in each of red, green and blue color planes of the image.

3. The system as recited in claim 2 wherein a resulting edge-detected image corresponds to a spatial set of separate partition areas having null-colored pixels.

4. The system as recited in claim 1 wherein the flood-fill operation fills partition areas that are surrounded by edges of colored pixels.

5. The system as recited in claim 1 wherein the set of heuristic tests includes accepting a partition area in the flood-filled image that exceeds a minimum number of pixels.

6. The system as recited in claim 1 wherein the set of heuristic tests includes accepting a partition area in the flood-filled image that has a bounding shape with a length to width ratio that is less than a selected maximum value.

7. The system as recited in claim 1 wherein the set of heuristic tests includes accepting a partition area in the flood-filled image if a color of a selected number of pixels therein is determined to be consistent with a reference color.

8. The system as recited in claim 7 wherein the reference color corresponds to one of the colors of the MacBeth color checker chart.

9. The system as recited in claim 1 wherein the set of heuristic tests includes accepting a partition area in the flood-filled image that has a ratio of its partition area to the number of pixels contained therein that exceeds a selected minimum ratio.

10. The system as recited in claim 1 wherein the set of heuristic tests includes accepting partition areas in the flood-filled image that are clustered together and have substantially equal aspect ratios containing about a same number of pixels.

11. A MacBeth color checker chart automatic detection method, comprising:

applying an edge detection operation to an image using one or more computer processors;

performing a flood-fill operation on the image using the one or more computer processors to provide a flood-filled image; and

testing the flood-filled image using the one or more computer processors to provide a modified flood-fill image, wherein a set of heuristic tests are employed to automatically determine quantity and location of MacBeth color checker charts.

12. The method as recited in claim 11 wherein the edge detection operation individually identifies edges in each of the red, green and blue color planes of the image.

13. The method as recited in claim 12 wherein a resulting edge-detected image corresponds to a spatial set of separate partition areas having no colored pixels.

14. The method as recited in claim 11 wherein the flood-fill operation fills partition areas that are surrounded by edges of colored pixels.

15. The method as recited in claim 11 wherein the set of heuristic tests includes accepting a partition area in the flood-filled image that exceeds a minimum number of pixels.

16. The method as recited in claim 11 wherein the set of heuristic tests includes accepting a partition area in the flood-filled image having a bounding shape with a length to width ratio that is less than a maximum value.

17. The method as recited in claim 11 wherein the set of heuristic tests includes accepting a partition area in the flood-filled image if a color of a selected number pixels therein is determined to be consistent with a reference color.

18. The method as recited in claim 17 wherein the reference color corresponds to the colors of the MacBeth color chart.

19. The method as recited in claim 11 wherein the set of heuristic tests includes accepting a partition area in the flood-filled image having a ratio of its partition area to the number of pixels contained therein that exceeds a selected minimum ratio.

20. The method as recited in claim 11 wherein the set of heuristic tests includes accepting partition areas in the flood-filled image that are clustered together and have substantially equal aspect ratios containing about a same number of pixels.