Picture reading method, program and device, principal color extracting method, program and device, and image dividing method, program and device

• US 20050238229A1
• Filed: 04/21/2005
• Published: 10/27/2005
• Est. Priority Date: 04/22/2004
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ishidera, Eiki
• Granted Patent: US 7,522,766 B2
• Time in Patent Office: Days
• US Class Current: 382/165
• CPC Class Codes: G06V 20/62 Text, e.g. of license plates, overlay texts or captions on TV images
• CPC Class Codes: G06V 20/625 License plates
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G06V 30/18105 related to colour

Abstract

A method for reading a picture is provided which is capable of removing adverse effects caused by lighting conditions or a like. A principal color extracting section extracts principal colors from a color image input by an image inputting section based on a local peak value shown in a color histogram obtained from the color image and divides the color image into principal color images each corresponding to each of the extracted principal colors. A combination creating section creates a combined image by combining separated principal color images. A picture region extracting section extracts character region candidates from the principal color image and combined image. A picture recognizing section performs character recognizing processing on all extracted character region candidates to obtain the best character reading result according to a character recognizing confidence of character recognizing processing results.

Claims

1. A picture reading method comprising:

a step of extracting color components having a high frequency of occurrence in an input image, as principal colors;

a step of separating the input image into images each corresponding to each of the extracted principal colors; and

a step of combining the separated images, out of the separated images, whose principal colors have specified relation with one another; and

a step of reading a picture based on the separated images and the combined images.

2. The picture reading method according to claim 1, wherein the extraction of the principal colors is performed by separating two or more color components contained in a calorimetric system representing the input image into a specified number of color component zones, by using a center of a first color component zone, as a temporary principal color center, when a color component value within the first color component zone forms a peak against color component values within second color component zones being adjacent to the first color component zone and exceeds a first pre-determined threshold value, by calculating a mean value of the color components having a value representing similarity of a color between the color components that is larger than a predetermined second threshold value, out of the color components being distributed with the temporary principal color center being used as a center and using the mean value as a principal color center, and by making each of the color components having a value representing similarity of a color between the color components that is larger than a predetermined third threshold value be contained in the principal colors, out of the color components being distributed with the principal color center being used as a center.

3. The picture reading method according to claim 1, wherein the separation of said images is performed by preparing an image for every extracted principal color, by judging as to whether a pixel for every prepared image input belongs to any one of the extracted principal colors, and by using as a first pixel value the pixel belonging to any one of the extracted principal colors, and on the other hand, by using as a second pixel value the pixel belonging to no one of the principal colors.

4. The picture reading method according to claim 1, wherein the reading of a picture is performed by extracting picture region candidates from the separated images and combined images, by performing picture recognizing processing on all the extracted picture region candidates, and by performing picture reading processing according to a result from said picture recognizing processing.

5. The picture reading method according to claim 4, wherein the extraction of picture region candidates is performed by excluding, from said picture region candidates, out of said picture region candidates in which pixel values representing the separated images and combined images occur continuously in horizontal and/or vertical directions, said picture region candidates in which the number of pixel values occurring continuously in horizontal and/or vertical directions is larger than a predetermined ratio of the number of pixels in the horizontal and vertical directions in the input image and by comparing the number of pixel values occurring continuously in the horizontal and/or vertical directions in coordinates serving as a center of the non-excluded picture region candidate with the number of the pixel occurring in the horizontal and vertical directions in the input image and by judging, based on results from the comparison, whether the non-excluded picture region candidate is used as said picture region candidates.

25. A controlling program to make a computer execute the picture reading method as set forth in claim 1.

6. A picture reading method comprising:

a step of extracting color components having a high frequency of occurrence in an input image, as principal colors;

a step of separating the input image into images each corresponding to each of the extracted principal colors;

a step of comparing a degree of difference in color among the principal colors making up each of the separated images;

a step of combining the separated images, out of the separated images, whose principal colors have specified relation with one another, based on a result from the comparison; and

a step of reading a picture based on the separated images and the combined images.

7. The picture reading method according to claim 6, wherein the extraction of the principal colors is performed by separating two or more color components contained in a calorimetric system representing the input image into a specified number of color component zones, by using a center of a first color component zone, as a temporary principal color center, when a color component value within the first color component zone forms a peak against color component values within second color component zones being adjacent to the first color component zone and exceeds a first pre-determined threshold value, by calculating a mean value of the color components having a value representing similarity of a color between the color components that is larger than a predetermined second threshold value, out of the color components being distributed with the temporary principal color center being used as a center and using the mean value as a principal color center, and by making each of the color components having a value representing similarity of a color between the color components that is larger than a predetermined third threshold value be contained in the principal colors, out of the color components being distributed with the principal color center being used as a center.

8. The picture reading method according to claim 6, wherein the separation of said images is performed by preparing an image for every extracted principal color, by judging as to whether a pixel for every prepared image input belongs to any one of the extracted principal colors, and by using as a first pixel value the pixel belonging to any one of the extracted principal colors, and on the other hand, by using as a second pixel value the pixel belonging to no one of the principal colors.

9. The picture reading method according to claim 6, wherein the reading of a picture is performed by extracting picture region candidates from the separated images and combined images, by performing picture recognizing processing on all the extracted picture region candidates, and by performing picture reading processing according to a result from said picture recognizing processing.

10. The picture reading method according to claim 9, wherein the extraction of picture region candidates is performed by excluding, from said picture region candidates, out of said picture region candidates in which pixel values representing the separated images and combined images occur continuously in horizontal and/or vertical directions, said picture region candidates in which the number of pixel values occurring continuously in horizontal and/or vertical directions is larger than a predetermined ratio of the number of pixels in the horizontal and vertical directions in the input image and by comparing the number of pixel values occurring continuously in the horizontal and/or vertical directions in coordinates serving as a center of the non-excluded picture region candidate with the number of the pixel occurring in the horizontal and vertical directions in the input image and by judging, based on results from the comparison, whether the non-excluded picture region candidate is used as said picture region candidates.

26. A controlling program to make a computer execute the picture reading method as set forth in claim 6.

11. A principal color extracting method comprising:

a step of separating two or more color components contained in a calorimetric system representing an input image into a specified number of color component zones;

a step of using a center of a first color component zone, as a temporary principal color center, when a color component value within the first color component zone forms a peak against color component values within second color component zones being adjacent to the first color component zone and exceeds a first pre-determined threshold value;

a step of calculating a mean value of the color components having a value representing similarity of a color between the color components that is larger than a predetermined second threshold value, out of the color components being distributed with the temporary principal color center being used as a center and using the mean value as a principal color center, and

a step of extracting as principal colors the color components each having a value representing similarity of a color between the color components that is larger than a predetermined third threshold value, out of the color components being distributed with the principal color center being used as a center.

27. A controlling program to make a computer execute the principal color extracting method as set forth in claim 11.

12. An image dividing method comprising:

a step of separating two or more color components contained in a colorimetric system representing an input image into a specified number of color component zones;

a step of using a center of a first color component zone, as a temporary principal color center, when a color component value within the first color component zone forms a peak against color component values within second color component zones being adjacent to the first color component zone and exceeds a first pre-determined threshold value;

a step of calculating a mean value of the color components having a value representing similarity of a color between the color components that is larger than a predetermined second threshold value, out of the color components being distributed with the temporary principal color center being used as a center and using the mean value as a principal color center;

a step of extracting as principal colors the color components each having a value representing similarity of a color between the color components being larger than a predetermined third threshold value, out of the color components being distributed with the principal color center being used as a center;

a step of preparing images each corresponding to each of the extracted principal colors,

a step of judging as to whether a pixel for every prepared image belongs to any one of the extracted principal colors; and

a step of separating an input image into images each corresponding to each of principal colors by using as a first pixel value the pixel belonging to any one of the extracted principal colors, and on the other hand, by using as a second pixel value the pixel belonging to no one of the principal colors, as obtained from the result of the judgment.

28. A controlling program to make a computer execute the image dividing method as set forth in claim 12.

13. A picture reading device comprising:

a principal color extracting section to extract color components having a high frequency of occurrence in an input image, as principal colors;

an image separating section to separate the input image into images each corresponding to each of the extracted principal colors extracted by said principal color extracting section;

an image combining section to combine the separated images, out of the separated images obtained by the separating operation of said image separating section, whose principal colors have specified relation with one another; and

a picture reading section to read a picture based on said images obtained by the separation by said image separating section and said images obtained by the combination by said image combining section.

14. The picture reading device according to claim 13, wherein said principal color extracting section comprises:

a separating section to separate two or more color components contained in a calorimetric system representing the input image into a specified number of color component zones;

a temporary principal color center determining section to determine a center of a first color component zone, as a temporary principal color center, when a color component value within the first color component zone obtained by operation of said separating section forms a peak against color component values within second color component zones being adjacent to the first color component zone and exceeds a first pre-determined threshold value;

a principal color center determining section to calculate a mean value of the color components having a value representing similarity of a color between the color components that is larger than a predetermined second threshold value, out of the color components being distributed with the temporary principal color center being used as a center and to determine the calculated mean value as a principal color center; and

an extracting section to extract as principal colors the color components each having a value representing similarity of a color between the color components that is larger than a predetermined third threshold value, out of the color components being distributed with the principal color center determined by said temporary principal color center determining section being used as a center.

15. The picture reading device according to claim 13, wherein said image separating section comprises:

an inputting section to input an image for every principal color extracted by said principal color extracting section; and

a creating section to create an image made up of principal colors by judging as to whether a pixel for every image input from said inputting section belongs to any one of the extracted principal colors, and by using as a first pixel value the pixel belonging to any one of the extracted principal colors, and on the other hand, by using as a second pixel value the pixel belonging to no one of the principal colors.

16. The picture reading device according to claim 13, wherein said picture reading section comprises:

a candidate extracting section to extract picture region candidates from said images obtained by the separation by said image separating section and the combined images obtained by the combination by said image combining section;

a picture recognizing section to perform picture recognizing processing on all picture region candidates extracted by said candidate extracting section; and

a reading section to read a picture based on a result from said picture recognizing processing obtained by the recognition by said picture recognizing section.

17. The picture reading device according to claim 16, wherein said candidate extracting section comprises:

a candidate excluding section to exclude, from said picture region candidates, out of said picture region candidates in which pixel values representing said images obtained by the separation by said image separating section and said images obtained by the combination by said image combining section occur continuously in horizontal and/or vertical directions, said picture region candidates in which the number of pixel values occurring continuously in the horizontal and/or vertical directions is larger than a predetermined ratio of the number of pixels in the horizontal and vertical directions in the input image;

a comparing section to compare the number of pixel values occurring continuously in the horizontal and/or vertical directions in coordinates serving as a center of the picture region candidate not having been excluded by said candidate excluding section with the number of pixels in the horizontal and vertical directions in the input image; and

a judging section to judge, based on results from the comparison by said comparing section, whether said picture region candidates not having been excluded are used as said picture region candidates.

29. A controlling program to make a computer serve as the picture reading device as set forth in claim 13.

31. A controlling program to make a computer serve as the principal color extracting device as set forth in claim 15.

32. A controlling program to make a computer serve as the image dividing device as set forth in claim 16.

18. A picture reading device comprising:

a principal color extracting section to extract color components having a high frequency of occurrence in an input image, as principal colors;

an image separating section to separate the input image into images each corresponding to each of the principal colors extracted by said principal color extracting section;

a comparing section to compare a degree of difference in color among the principal colors making up the images separated by said image separating section;

an image combining section to combine the separated images, out of the separated images, whose principal colors have specified relation with one another, based on a result from the comparison by said comparing section; and

a picture reading section to read a picture based on images obtained by the separating operation of said image separating section and said images obtained by the combination by said image combining section.

19. The picture reading device according to claim 18, wherein said principal color extracting section comprises:

a separating section to separate two or more color components contained in a calorimetric system representing the input image into a specified number of color component zones;

a temporary principal color center determining section to determine a center of a first color component zone, as a temporary principal color center, when a color component value within the first color component zone obtained by operation of said separating section forms a peak against color component values within second color component zones being adjacent to the first color component zone and exceeds a first pre-determined threshold value;

a principal color center determining section to calculate a mean value of the color components having a value representing similarity of a color between the color components that is larger than a predetermined second threshold value, out of the color components being distributed with the temporary principal color center being used as a center and to determine the calculated mean value as a principal color center; and

an extracting section to extract as principal colors the color components each having a value representing similarity of a color between the color components that is larger than a predetermined third threshold value, out of the color components being distributed with the principal color center determined by said temporary principal color center determining section being used as a center.

20. The picture reading device according to claim 18, wherein said image separating section comprises:

an inputting section to input an image for every principal color extracted by said principal color extracting section; and

a creating section to create an image made up of principal colors by judging as to whether a pixel for every image input from said inputting section belongs to any one of the extracted principal colors, and by using as a first pixel value the pixel belonging to any one of the extracted principal colors, and on the other hand, by using as a second pixel value the pixel belonging to no one of the principal colors.

21. The picture reading device according to claim 18, wherein said picture reading section comprises:

a candidate extracting section to extract picture region candidates from said images obtained by the separation by said image separating section and the combined images obtained by the combination by said image combining section;

a picture recognizing section to perform picture recognizing processing on all picture region candidates extracted by said candidate extracting section; and

a reading section to read a picture based on a result from said picture recognizing processing obtained by the recognition by said picture recognizing section.

22. The picture reading device according to claim 21, wherein said candidate extracting section comprises:

a candidate excluding section to exclude, from said picture region candidates, out of said picture region candidates in which pixel values representing said images obtained by the separation by said image separating section and said images obtained by the combination by said image combining section occur continuously in horizontal and/or vertical directions, said picture region candidates in which the number of pixel values occurring continuously in the horizontal and/or vertical directions is larger than a predetermined ratio of the number of pixels in the horizontal and vertical directions in the input image;

a comparing section to compare the number of pixel values occurring continuously in the horizontal and/or vertical directions in coordinates serving as a center of the picture region candidate not having been excluded by said candidate excluding section with the number of pixels in the horizontal and vertical directions in the input image; and

a judging section to judge, based on results from the comparison by said comparing section, whether said picture region candidates not having been excluded are used as said picture region candidates.

30. A controlling program to make a computer serve as the picture reading device as set forth in claim 18.

23. A principal color extracting device comprising:

a separating section to separate two or more color components contained in a calorimetric system representing an input image into a specified number of color component zones;

a temporary principal color center determining section to determine a center of a first color component zone, as a temporary principal color center, when a color component value within the first color component zone obtained by operation of said separating section forms a peak against color component values within second color component zones being adjacent to the first color component zone and exceeds a first pre-determined threshold value;

a principal color center determining section to calculate a mean value of the color components having a value representing similarity of a color between the color components that is larger than a predetermined second threshold value, out of the color components being distributed with the temporary principal color center determined by said temporary principal color center determining section being used as a center and to determine the calculated mean value as a principal color center; and

an extracting section to extract, as principal colors, the color components each having a value representing similarity of a color between the color components that is larger than a predetermined third threshold value, out of the color components being distributed with the principal color center determined by said temporary principal color center determining section being used as a center.

24. An image dividing device comprising:

a separating section to separate two or more color components contained in a calorimetric system representing the input image into a specified number of color component zones;

a temporary principal color center determining section to determine a center of a first color component zone, as a temporary principal color center, when a color component value within the first color component zone obtained by operation of said separating section forms a peak against color component values within second color component zones being adjacent to the first color component zone and exceeds a first pre-determined threshold value;

a principal color center determining section to calculate a mean value of the color components having a value representing similarity of a color between the color components being larger than a predetermined second threshold value, out of the color components being distributed with the temporary principal color center determined by said temporary principal color center determining section being used as a center and to determine the calculated mean value as a principal color center;

an extracting section to extract, as principal colors, the color components each having a value representing similarity of a color between the color components that is larger than a predetermined third threshold value, out of the color components being distributed with the principal color center determined by said temporary principal color center determining section being used as a center;

an inputting section to input an image for every said principal color extracted by said extracting section; and

a principal color image outputting section to output an image made up of principal colors by judging as to whether a pixel for every image input from said inputting section belongs to any one of the extracted principal colors, and by using as a first pixel value the pixel belonging to any one of the extracted principal colors, and on the other hand, by using as a second pixel value the pixel belonging to no one of the principal colors.