IMAGE PROCESSING METHOD, IMAGE PROCESSING APPARATUS, AND SYSTEM

• US 20090179824A1
• Filed: 12/31/2008
• Published: 07/16/2009
• Est. Priority Date: 01/10/2008
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tsujimoto, Takuya, Inoguchi, Kazutaka
• Granted Patent: US 8,242,975 B2
• Time in Patent Office: Days
• US Class Current: 345/7
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/0116 comprising devices for correcting chromatic aberration
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G09G 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T
• CPC Class Codes: G09G 5/026 Control of mixing and/or overlay of colours in general G09G5/022 and G09G5/024 take precedence
• CPC Class Codes: H04N 25/611 Correction of chromatic aberration

Abstract

One of a plurality of color components which form pixels in an image that is influenced by chromatic aberrations caused by an optical system is selected as a reference color, and coordinates after conversion are calculated by applying conversion for correcting a distortion of the optical system with respect to the image to coordinates of pixels in association with the reference color. Correction values indicating amounts of color misregistration are calculated using the proportional relationship of difference values between the calculated coordinates and coordinates obtained by applying the conversion to coordinates of the image in association with remaining colors except for the reference color of the plurality of color components. Based on the calculated correction values, coordinates obtained by applying the conversion to coordinates of the image in association with the remaining colors are calculated.

Claims

1. An image processing method for correcting an image which is influenced by chromatic aberrations caused by an optical system, comprising:

a step of selecting, as a reference color, one of a plurality of color components included in the image;

an acquisition step of acquiring pixel positions after conversion, which are obtained by applying conversion processing for correcting a distortion of the optical system with respect to the image, to pixel positions of pixels having the reference color as the color component;

a first calculation step of calculating, using difference values between the pixel positions after conversion and pixel positions obtained by applying the conversion processing to pixel positions of pixels having one of remaining colors except for the reference color as the color component of the plurality of color components, and a predetermined value, pixel positions obtained by applying the conversion processing to pixel positions of pixels having the other remaining color as the color component;

a second calculation step of calculating, based on the difference values, pixel positions obtained by applying the conversion processing to pixel positions of pixels having the one remaining color as the color component; and

a step of correcting the image by allocating pixels having the reference color as the color component at the pixel positions acquired in the acquisition step, allocating pixels having the other remaining color as the color component at the pixel positions calculated in the first calculation step, and allocating pixels having the one remaining color as the color component at the pixel positions calculated in the second calculation step.

25. A computer-readable storage medium storing a program for making a computer execute an image processing method according to claim 1.

2. An image processing apparatus for correcting an image which is influenced by chromatic aberrations caused by an optical system, comprising:

means for selecting, as a reference color, one of a plurality of color components included in the image;

acquisition means for acquiring pixel positions after conversion, which are obtained by applying conversion processing for correcting a distortion of the optical system with respect to the image, to pixel positions of pixels having the reference color as the color component;

first calculation means for calculating, using difference values between the pixel positions after conversion and pixel positions obtained by applying the conversion processing to pixel positions of pixels having one of remaining colors except for the reference color as the color component of the plurality of color components, and a predetermined value, pixel positions obtained by applying the conversion processing to pixel positions of pixels having the other remaining color as the color component;

second calculation means for calculating, based on the difference values, pixel positions obtained by applying the conversion processing to pixel positions of pixels having the one remaining color as the color component; and

means for correcting the image by allocating pixels having the reference color as the color component at the pixel positions acquired by said acquisition means, allocating pixels having the other remaining color as the color component at the pixel positions calculated by said first calculation means, and allocating pixels having the one remaining color as the color component at the pixel positions calculated by said second calculation means.

3. An image processing method for correcting an image which is influenced by chromatic aberrations caused by an optical system, comprising:

a first coordinate calculation step of selecting, as a reference color, one of a plurality of color components which form each pixel in the image, and calculating coordinates after conversion by applying conversion for correcting a distortion of an optical system with respect to the image to coordinates of pixels in association with the reference color;

a chromatic aberration correction value calculation step of calculating correction values indicating amounts of color misregistration using a proportional relationship of difference values between the coordinates calculated in the first coordinate calculation step, and coordinates obtained by applying the conversion to coordinates of the image in association with remaining colors except for the reference color of the plurality of color components; and

a second coordinate calculation step of calculating coordinates obtained by applying the conversion to coordinates of the image in association with the remaining colors based on the correction values calculated in the chromatic aberration correction value calculation step.

7. The method according to claim 3, wherein the chromatic aberration correction value calculation step comprises:

a first correction value calculation step of calculating correction values of at least one of the remaining colors except for the reference color using the proportional relationship of difference values; and

a second correction value calculation step of calculating correction values of a color except for the reference color and the target color in the first correction value calculation step.

8. The method according to claim 7, wherein in the first correction value calculation step, the correction values are calculated using a relationship that a ratio of differences between the coordinates after conversion calculated in the first coordinate calculation step and coordinate values obtained from the correction values calculated in the second correction value calculation step, and differences between the coordinates after conversion and coordinate values obtained from the correction values of the target color in the first correction value calculation step is constant.

11. The method according to claim 3, wherein the coordinates after conversion calculated in the first coordinate calculation step have values on respective axes on a two-dimensional coordinate system.

12. The method according to claim 7, wherein in the second correction value calculation step, a reference table is used to calculate the correction values.

13. The method according to claim 12, wherein the reference table stores difference values between the coordinates after conversion calculated in the first coordinate calculation step and coordinates after conversion on the two-dimensional coordinate system of the target color in the second correction value calculation step.

14. The method according to claim 12, wherein the reference table has, as a table, values of distances between the coordinates after conversion calculated in the first coordinate calculation step and coordinates on the two-dimensional coordinate system of the target color in the second correction value calculation step.

15. The method according to claim 14, wherein in the second correction value calculation step, the correction values are calculated based on a direction that connects the values of the distances stored in the reference table, an optical origin, and the coordinates after conversion calculated in the first coordinate calculation step.

16. The method according to claim 7, wherein in the second correction value calculation step, an approximate polynomial is used to calculate the correction values.

17. The method according to claim 7, wherein as one color used in the first correction value calculation step, a color of the remaining colors except for the reference color, which has a shortest distance between the coordinates after conversion calculated in the first coordinate calculation step and the remaining color, is adopted.

18. The method according to claim 3, further comprising a control step of independently having a designation as to whether or not to enable distortion aberration and chromatic aberration correction functions.

19. The method according to claim 18, wherein in the control step, when the distortion aberration correction function is enabled, and the chromatic aberration correction function is disabled, control is made to set the correction values calculated in the chromatic aberration correction value calculation step to be zero.

20. The method according to claim 18, wherein in the control step, when the distortion aberration correction function is disabled, and the chromatic aberration correction function is enabled, control is made to adopt coordinate values before conversion as the coordinates after conversion calculated in the first coordinate calculation step.

21. The method according to claim 3, wherein control is made to set the correction values calculated in the chromatic aberration correction value calculation step to be zero within a range of an area designated by coordinates.

22. The method according to claim 3, wherein control is made to set the correction values to be zero when the correction values calculated in the chromatic aberration correction value calculation step are compared with a set threshold, and the correction values are not more than or less than the threshold.

23. The method according to claim 22, wherein control is made to set all correction values of the remaining colors to be zero when the correction values of at least one color of the remaining colors except for the reference color are compared with a threshold and are not more than the threshold.

24. The method according to claim 3, wherein in the first and second coordinate calculation steps, when the number of pixels which form an image to be corrected is larger than the number of corresponding pixels held in a reference table, coordinates of pixels between neighboring representative pixels in the reference table are calculated by interpolation processing.

4. An image processing apparatus for correcting an image which is influenced by chromatic aberrations caused by an optical system, comprising:

first coordinate calculation means for selecting, as a reference color, one of a plurality of color components which form each pixel in the image, and calculating coordinates after conversion by applying conversion for correcting a distortion of an optical system with respect to the image to coordinates of pixels in association with the reference color;

chromatic aberration correction value calculation means for calculating correction values indicating amounts of color misregistration using a proportional relationship of difference values between the coordinates calculated by said first coordinate calculation means, and coordinates obtained by applying the conversion to coordinates of the image in association with remaining colors except for the reference color of the plurality of color components; and

second coordinate calculation means for calculating coordinates obtained by applying the conversion to coordinates of the image in association with the remaining colors based on the correction values calculated by said chromatic aberration correction value calculation means.

9. The apparatus according to claim 4, wherein said chromatic aberration correction value calculation means comprises:

first correction value calculation means for calculating correction values of at least one of the remaining colors except for the reference color using the proportional relationship of difference values; and

second correction value calculation means for calculating correction values of a color except for the reference color and the target color in said first correction value calculation means.

10. The apparatus according to claim 9, wherein said first correction value calculation means calculates the correction values using a relationship that a ratio of differences between the coordinates after conversion calculated by said first coordinate calculation means and coordinate values obtained from the correction values calculated by said second correction value calculation means, and differences between the coordinates after conversion and coordinate values obtained from the correction values of the target color in said first correction value calculation means is constant.

5. An image processing system for correcting an image which is influenced by chromatic aberrations caused by an optical system in an apparatus which comprises image capturing means for capturing an image of a physical space, input means for inputting a display image, and display means for displaying the display image in an enlarged scale, comprising:

first coordinate calculation means for selecting, as a reference color, one of a plurality of color components which form each pixel in the image, and calculating coordinates after conversion by applying conversion for correcting a distortion of an image capturing optical system with respect to the image to coordinates of pixels in association with the reference color;

chromatic aberration correction value calculation means for calculating correction values indicating amounts of color misregistration using a proportional relationship of difference values between the coordinates calculated by said first coordinate calculation means, and coordinates obtained by applying the conversion to coordinates of the image in association with remaining colors except for the reference color of the plurality of color components;

second coordinate calculation means for calculating coordinates obtained by applying the conversion to coordinates of the image in association with the remaining colors based on the correction values calculated by said chromatic aberration correction value calculation means; and

means for calculating new pixel values at interpolation positions based on the coordinates respectively calculated by said first and second coordinate calculation means, and values which form pixels before conversion.

6. An image processing system for correcting an image which is influenced by chromatic aberrations caused by an optical system in an apparatus which comprises image capturing means for capturing an image of a physical space, input means for inputting a display image, and display means for displaying the display image via an enlargement optical system, comprising:

first coordinate calculation means for selecting, as a reference color, one of a plurality of color components which form each pixel in the image, and calculating coordinates after conversion by applying conversion for correcting a distortion of an image capturing optical system and/or a distortion of a display optical system with respect to the image to coordinates of pixels in association with the reference color;

chromatic aberration correction value calculation means for calculating correction values indicating amounts of color misregistration using a proportional relationship of difference values between the coordinates calculated by said first coordinate calculation means, and coordinates obtained by applying the conversion to coordinates of the image in association with remaining colors except for the reference color of the plurality of color components;

second coordinate calculation means for calculating coordinates obtained by applying the conversion to coordinates of the image in association with the remaining colors based on the correction values calculated by said chromatic aberration correction value calculation means; and

means for calculating new pixel values at interpolation positions based on the coordinates respectively calculated by said first and second coordinate calculation means, and values which form pixels before conversion.