Color reproduction corrector for image input device and color reproduction correction method

• US 20030113014A1
• Filed: 11/13/2002
• Published: 06/19/2003
• Est. Priority Date: 10/31/2000
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Katoh, Naoya
• Granted Patent: US 7,227,571 B2
• Time in Patent Office: Days
• US Class Current: 382/167
• CPC Class Codes: H04N 1/6083 controlled by factors external to the apparatus
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control
• CPC Class Codes: H04N 9/73 Colour balance circuits, e.g. white balance circuits or colour temperature control camera processing pipelines for colour balance H04N23/88

Abstract

The present invention has an object to provide a color reproduction correcting device for image input apparatus capable of excellently reproducing colors without difficulties, even when an image is reproduced under an observation light source that is different from an image pick-up light source in terms of color rendering. The present invention has white balance matrix production means 130 that receives chromaticity point data from the image input apparatus to produce a correction matrix for white balance, light source type determination means 140 that receives information on the image pick-up light source from the image input apparatus to determine the types of the image pick-up light source and an image color reproduction light source, transformation matrix production means 150 that produces a transformation matrix reflecting the optical characteristics of the picked-up object by using predetermined color matching function data, spectral characteristic data regarding the image pick-up light source and color reproduction light source, of the types determined by the light source type determination means 140, optical characteristics data on a predetermined picked-up object, and correction matrix data for white balance, and color correction processing means 170 that performs color reproduction correction with respect to the image data using the transformation matrix.

Claims

1. A color reproduction correcting device for an image data picked up by an image input apparatus which outputs information regarding a type of an image pick-up light source and information containing chromaticity point data of the image pick-up light source, that is to say information on the estimated result of the image pick-up light source, the color reproduction correcting device for an image input apparatus characterized by comprising:

white balance matrix production means for receiving the chromaticity point data from the image input apparatus to produce a correction matrix for white balance;

light source type determination means for receiving information on the image pick-up light source from the image input apparatus to determine the types of an image pick-up light source and an image color reproduction light source;

transformation matrix production means for producing a transformation matrix reflecting the optical characteristics of the picked-up object, using predetermined color matching function data, spectral characteristic data regarding the image pick-up light source and color reproduction light source of the types determined by the light source type determination means, optical characteristic data on a predetermined picked-up object and the correction matrix data for white balance; and

color correction processing means for performing color reproduction correction with respect to the image data, using the transformation matrix.

2. The color reproduction correcting device for an image input apparatus according to claim 1, further comprising weighted transformation matrix production means for applying a predetermined constant as a weighting factor and calculating a sum of the product of the transformation matrix and the weighting factor and the product of the unit matrix in the same size as that of the transformation matrix and the weighting factor, to produce a weighted transformation matrix, wherein

the color correction processing means uses the weighted transformation matrix as a transformation matrix for color reproduction correction.

3. The color reproduction correcting device for an image input apparatus according to claim 1, wherein

the transformation matrix produced in the transformation matrix production means is the matrix to which white balance is applied;

and the color correction processing means uses the transformation matrix to which the white balance is applied as a transformation matrix for color reproduction correction under a light source of the same type.

4. The color reproduction correcting device for an image input apparatus according to claim 2, wherein

the transformation matrix produced in the transformation matrix production means is the matrix to which white balance is applied;

and the color correction processing means uses the transformation matrix to which white balance is applied as a transformation matrix for color reproduction correction under the same type of light source.

5. The color reproduction correcting device for an image input apparatus according to claim 1, wherein

the optical characteristic data of the picked-up object includes principal component analysis data obtained by principal component analyses, or colorimetry data obtained by performing colorimetry with respect to a picked-up object whose colors are equally distributed in a color space;

and the color correction processing means uses the transformation matrix produced by the transformation matrix production means using the principal component analysis data or the colorimetry data, as the transformation matrix for color reproduction correction.

6. The color reproduction correcting device for an image input apparatus according to claim 2, wherein

the optical characteristic data of the picked-up object includes principal component analysis data obtained by principal component analyses, or colorimetry data obtained by performing colorimetry with respect to the picked-up object whose colors are equally distributed in a color space;

and the color correction processing means uses the transformation matrix produced by the transformation matrix production means using the principal component analysis data or the colorimetry data, as the transformation matrix for color reproduction correction.

7. The color reproduction correcting device for an image input apparatus according to claim 3, wherein

the optical characteristic data of the picked-up object includes principal component analysis data obtained by principal component analyses, or colorimetry data obtained by performing colorimetry with respect to the picked-up object whose colors are equally distributed in a color space;

and the transformation matrix produced by using the color correction data is used as the transformation matrix for color reproduction correction.

8. The color reproduction correcting device for an image input apparatus according to claim 4, wherein

the optical characteristic data of the picked-up object includes principal component analysis data obtained by principal component analyses, or colorimetry data obtained by performing colorimetry with respect to the picked-up object whose colors are equally distributed in a color space;

and the color correction processing means uses the transformation matrix produced by the transformation matrix production means using the principal component analysis data or the colorimetry data, as the transformation matrix for color reproduction correction.

9. A color reproduction correcting method for an image data picked up by the image input apparatus which outputs information on the type of a image pick-up light source and information containing chromaticity point data of the image pick-up light source, that is to say information on the estimated result of the image pick-up light source, the color reproduction correcting method for an image input apparatus, characterized by comprising the steps of:

receiving the chromaticity point data from the image input apparatus to produce a correction matrix for white balance;

receiving the information on the image pick-up light source from the image input apparatus to determine the types of an image pick-up light source and an image color reproduction light source;

producing transformation matrix reflecting the optical characteristics of the picked-up object, using predetermined color matching function data, spectral characteristic data regarding the image pick-up light source and color reproduction light source, of the types determined by the light source type determination step, optical characteristic data on a predetermined picked-up object and correction matrix data for white balance; and

processing color correction by performing color reproduction correction with respect to the image data, using the transformation matrix.

10. The color reproduction correcting method for an image input apparatus according to claim 9, further comprising the step of producing a weighted transformation matrix by applying a predetermined constant as a weighting factor, and calculating a sum of the product of the transformation matrix and the weighting factor and the product of the unit matrix in the same size as that of the transformation matrix and the weighting factor, to produce a weighted transformation matrix, wherein

the color correction processing step uses the weighted transformation matrix as a transformation matrix for color reproduction correction.

11. The color reproduction correcting method for an image input apparatus according to claim 9, wherein

the transformation matrix produced in the transformation matrix production step is the matrix to which white balance is applied;

and the color correction processing step uses the transformation matrix to which white balance is applied as a transformation matrix for color reproduction correction under a light source of the same type.

12. The color reproduction correcting method for an image input apparatus according to claim 10, wherein

the transformation matrix produced in the transformation matrix production step is the matrix to which white balance is applied;

and the color correction processing step uses the transformation matrix to which white balance is applied, as a transformation matrix for color reproduction correction under a light source of the same type.

13. The color reproduction correcting device for an image input apparatus according to claim 9, wherein

the optical characteristic data of the picked-up object includes principal component analysis data obtained by principal component analyses, or colorimetry data obtained by performing colorimetry with respect to a picked-up object whose colors are equally distributed in a color space;

and the color correction processing step uses the transformation matrix produced by the transformation matrix production step using the principal component analysis data or the colorimetry data, as the transformation matrix for performing color reproduction correction.

14. The color reproduction correcting method for an image input apparatus according to claim 10, wherein

the optical characteristic data of the picked-up object includes principal component analysis data obtained by principal component analyses, or colorimetry data obtained by performing colorimetry with respect to a picked-up object whose colors are equally distributed in a color space;

and the color correction processing step uses the transformation matrix produced by the transformation matrix production step using the principal component analysis data or the colorimetry data, as the transformation matrix for performing color reproduction correction.

15. The color reproduction correcting method for an image input apparatus according to claim 11, wherein

the optical characteristic data of the picked-up object includes principal component analysis data obtained by principal component analyses, or colorimetry data obtained by performing colorimetry with respect to a picked-up object whose colors are equally distributed in a color space;

and the color correction processing step uses the transformation matrix as the transformation matrix for color reproduction correction.

16. The color reproduction correcting method for an image input apparatus according to claim 12, wherein

the optical characteristic data of the picked-up object includes principal component analysis data obtained by principal component analyses, or colorimetry data obtained by performing colorimetry with respect to a picked-up object whose colors are equally distributed in a color space;

and the color correction processing step uses the transformation matrix produced by the transformation matrix production step using the principal component analysis data or the colorimetry data, as the transformation matrix for performing color reproduction correction.