IMAGE COMPARISON USING COLOR HISTOGRAMS

• US 20150078658A1
• Filed: 11/24/2014
• Published: 03/19/2015
• Est. Priority Date: 12/13/2011
• Status: Active Grant

• Current Assignee: The Nielsen Company LLC (MOOD Media Corporation)
• Original Assignee: The Nielsen Company LLC (MOOD Media Corporation)
• Inventors: Lee, Morris
• Granted Patent: US 9,613,290 B2
• Time in Patent Office: Days
• US Class Current: 382/165
• CPC Class Codes: G06F 16/785 using colour or luminescence
• CPC Class Codes: G06V 10/255 Detecting or recognising potential candidate objects based on visual cues, e.g. shapes
• CPC Class Codes: G06V 10/50 by performing operations within image blocks; by using histograms, e.g. histogram of oriented gradients [HoG]; by summing image-intensity values; Projection analysis
• CPC Class Codes: G06V 10/56 relating to colour
• CPC Class Codes: G06V 20/48 Matching video sequences

Abstract

Methods, apparatus and articles of manufacture for image comparison using color histograms are disclosed. Example methods disclosed herein to compare images include adjusting a color histogram associated with an input image based on a first reference color histogram associated with a first reference image to determine a first adjusted color histogram associated with the input image. Such example methods also include comparing the first adjusted color histogram and the first reference color histogram to determine whether the first reference image matches the input image. Such example methods further include displaying a version of the first reference image adjacent to a display of the input image in response to determining that the first reference image matches the input image.

Claims

1. A method to compare images, the method comprising:

adjusting a color histogram associated with an input image based on a first reference color histogram associated with a first reference image to determine a first adjusted color histogram associated with the input image;

comparing the first adjusted color histogram and the first reference color histogram to determine whether the first reference image matches the input image; and

displaying a version of the first reference image adjacent to a display of the input image in response to determining that the first reference image matches the input image.

2. A method as defined in claim 1, further comprising:

adjusting the color histogram associated with the input image based on a second reference color histogram associated with a second reference image to determine a second adjusted color histogram associated with the input image;

comparing the second adjusted color histogram and the second reference color histogram to determine whether the second reference image matches the input image; and

displaying a version of the second reference image adjacent to a display of the input image in response to determining that the second reference image matches the input image.

3. A method as defined in claim 1, wherein adjusting the color histogram associated with the input image comprises adjusting the color histogram associated with the input image based on the first reference color histogram and a scale factor to determine the first adjusted color histogram associated with the input image.

4. A method as defined in claim 3, wherein adjusting the color histogram associated with the input image based on the first reference color histogram and the scale factor comprises:

multiplying a value of a first bin of the color histogram associated with the input image by the scale factor to determine a scaled bin value; and

determining an adjusted value of a corresponding first bin of the first adjusted color histogram to be a smaller of the scaled bin value and a value of a corresponding first bin of the reference color histogram.

5. A method as defined in claim 1, wherein comparing the first adjusted color histogram and the first reference color histogram comprises:

determining a sum of differences between bins of the first adjusted color histogram and corresponding bins of the first reference color histogram; and

comparing the sum to a threshold to determine whether the first reference image matches the input image.

6. A method as defined in claim 1, wherein the version of the first reference image corresponds to a thumbnail version of the first reference image.

7. A method as defined in claim 1, further comprising:

capturing the input image with a camera; and

processing digital pixels of the input image to determine the color histogram associated with the input image.

8. A tangible computer readable medium comprising computer readable instructions which, when executed, cause a processor to at least:

adjust a color histogram associated with an input image based on a first reference color histogram associated with a first reference image to determine a first adjusted color histogram associated with the input image;

compare the first adjusted color histogram and the first reference color histogram to determine whether the first reference image matches the input image; and

display a version of the first reference image adjacent to a display of the input image in response to determining that the first reference image matches the input image.

9. A tangible computer readable medium as defined in claim 8, wherein the instructions, when executed, further cause the processor to:

adjust the color histogram associated with the input image based on a second reference color histogram associated with a second reference image to determine a second adjusted color histogram associated with the input image;

compare the second adjusted color histogram and the second reference color histogram to determine whether the second reference image matches the input image; and

display a version of the second reference image adjacent to a display of the input image in response to determining that the second reference image matches the input image.

10. A tangible computer readable medium as defined in claim 8, wherein to adjust the color histogram associated with the input image, the instructions, when executed, further cause the processor to adjust the color histogram associated with the input image based on the first reference color histogram and a scale factor to determine the first adjusted color histogram associated with the input image.

11. A tangible computer readable medium as defined in claim 10, wherein to adjust the color histogram associated with the input image based on the first reference color histogram and the scale factor, the instructions when executed, further cause the processor to:

multiply a value of a first bin of the color histogram associated with the input image by the scale factor to determine a scaled bin value; and

determine an adjusted value of a corresponding first bin of the first adjusted color histogram to be a smaller of the scaled bin value and a value of a corresponding first bin of the reference color histogram.

12. A tangible computer readable medium as defined in claim 8, wherein to compare the first adjusted color histogram and the first reference color histogram, the instructions, when executed, further cause the processor to:

determine a sum of differences between bins of the first adjusted color histogram and corresponding bins of the first reference color histogram; and

compare the sum to a threshold to determine whether the first reference image matches the input image.

13. A tangible computer readable medium as defined in claim 8, wherein the version of the first reference image corresponds to a thumbnail version of the first reference image.

14. A tangible computer readable medium as defined in claim 8, wherein the instructions, when executed, further cause the processor to:

capture the input image with a camera; and

process digital pixels of the input image to determine the color histogram associated with the input image.

15. An apparatus to compare images, the apparatus comprising:

a histogram comparator to;

adjust a color histogram associated with an input image based on a first reference color histogram associated with a first reference image to determine a first adjusted color histogram associated with the input image; and

compare the first adjusted color histogram and the first reference color histogram to determine whether the first reference image matches the input image; and

a results interface to display a version of the first reference image adjacent to a display of the input image in response to determining that the first reference image matches the input image.

16. An apparatus as defined in claim 15, wherein the histogram comparator comprises a bin adjuster to adjust the color histogram associated with the input image based on the first reference color histogram and a scale factor to determine the first adjusted color histogram associated with the input image.

17. An apparatus as defined in claim 16, wherein the bin adjuster is further to:

multiply a value of a first bin of the color histogram associated with the input image by the scale factor to determine a scaled bin value; and

determine an adjusted value of a corresponding first bin of the first adjusted color histogram to be a smaller of the scaled bin value and a value of a corresponding first bin of the reference color histogram.

18. An apparatus as defined in claim 15, wherein the histogram comparator comprises:

a comparison metric determiner to determine a sum of differences between bins of the first adjusted color histogram and corresponding bins of the first reference color histogram; and

a threshold comparator to compare the sum to a threshold to determine whether the first reference image matches the input image.

19. An apparatus as defined in claim 15, wherein the version of the first reference image corresponds to a thumbnail version of the first reference image.

20. An apparatus as defined in claim 15, further comprising:

an image interface to capture the input image with a camera; and

a histogram generator to process digital pixels of the input image to determine the color histogram associated with the input image.