Image processing apparatus, image processing method, and non-transitory computer readable medium

1. An image processing apparatus comprising:

an extraction unit that extracts a local color displacement, the local color displacement being a local displacement of color in a region of interest in a given image; and

a calculation unit that calculates a similarity between the local color displacement and an extracted-color displacement, the extracted-color displacement being a displacement of a preset color.

2. The image processing apparatus according to claim 1 , further comprising:

an extracted-color displacement setting unit that sets the extracted-color displacement using a direction of a local color displacement obtained from each region of interest and using a direction of a displacement of a given color.

3. The image processing apparatus according to claim 2 , wherein the calculation unit further calculates a similarity between the local color displacement and a non-extracted-color displacement, the non-extracted-color displacement being a displacement of a color set in advance not to be extracted, and calculates an overall similarity using the similarity between the local color displacement and the extracted-color displacement and the similarity between the local color displacement and the non-extracted-color displacement, the overall similarity being used as a similarity of the region of interest.

4. The image processing apparatus according to claim 3 , further comprising:

a non-extracted-color displacement setting unit that collects frequencies of occurrence of local color displacements obtained from regions of interest to determine a local-maxima color displacement and that sets the non-extracted-color displacement based on the local-maxima color displacement.

5. The image processing apparatus according to claim 3 , further comprising:

a binarization unit that binarizes the region of interest using the similarity between the local color displacement and the extracted-color displacement.

6. The image processing apparatus according to claim 5 , wherein the binarization unit binarizes the similarity.

7. The image processing apparatus according to claim 5 , wherein the binarization unit performs enhancement processing on the image in accordance with the similarity, and binarizes an image subjected to the enhancement processing.

8. The image processing apparatus according to claim 7 , wherein the binarization unit performs enhancement processing on the image so that the larger the value the similarity has, the greater the effect the enhancement processing has, to enhance a region where information is embedded in the image.

9. The image processing apparatus according to claim 1 , wherein the calculation unit further calculates a similarity between the local color displacement and a non-extracted-color displacement, the non-extracted-color displacement being a displacement of a color set in advance not to be extracted, and calculates an overall similarity using the similarity between the local color displacement and the extracted-color displacement and the similarity between the local color displacement and the non-extracted-color displacement, the overall similarity being used as a similarity of the region of interest.

10. The image processing apparatus according to claim 9 , further comprising:

a non-extracted-color displacement setting unit that collects frequencies of occurrence of local color displacements obtained from regions of interest to determine a local-maxima color displacement and that sets the non-extracted-color displacement based on the local-maxima color displacement.

11. The image processing apparatus according to claim 9 , further comprising:

a binarization unit that binarizes the region of interest using the similarity between the local color displacement and the extracted-color displacement.

12. The image processing apparatus according to claim 11 , wherein the binarization unit binarizes the similarity.

13. The image processing apparatus according to claim 11 , wherein the binarization unit performs enhancement processing on the image in accordance with the similarity, and binarizes an image subjected to the enhancement processing.

14. The image processing apparatus according to claim 13 , wherein the binarization unit performs enhancement processing on the image so that the larger the value the similarity has, the greater the effect the enhancement processing has, to enhance a region where information is embedded in the image.

15. The image processing apparatus according to claim 1 , further comprising:

a binarization unit that binarizes the region of interest using the similarity between the local color displacement and the extracted-color displacement.

16. The image processing apparatus according to claim 15 , wherein the binarization unit binarizes the similarity.

17. The image processing apparatus according to claim 15 , wherein the binarization unit performs enhancement processing on the image in accordance with the similarity, and binarizes an image subjected to the enhancement processing.

18. The image processing apparatus according to claim 17 , wherein the binarization unit performs enhancement processing on the image so that the larger the value the similarity has, the greater the effect the enhancement processing has, to enhance a region where information is embedded in the image.

19. A non-transitory computer readable medium storing a program causing a computer to execute a process for performing image processing, the process comprising:

extracting a local color displacement, the local color displacement being a local displacement of color in a region of interest in a given image; and

calculating a similarity between the local color displacement and an extracted-color displacement, the extracted-color displacement being a displacement of a preset color.

20. An image processing method comprising:

extracting a local color displacement, the local color displacement being a local displacement of color in a region of interest in a given image; and

calculating a similarity between the local color displacement and an extracted-color displacement, the extracted-color displacement being a displacement of a preset color.