COLOR MATCHING FOR IMAGING SYSTEMS

• US 20160275658A1
• Filed: 03/20/2015
• Published: 09/22/2016
• Est. Priority Date: 03/20/2015
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Klein, Moran, Paus, Dmitry
• Granted Patent: US 9,659,354 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06T 11/001 Texturing; Colouring; Generation of texture or colour inpainting G06T5/77
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 2207/20021 Dividing image into blocks, subimages or windows
• CPC Class Codes: G06T 2207/20208 High dynamic range [HDR] image processing
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 5/77 Retouching; Inpainting; Scratch removal
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: H04N 1/6052 Matching two or more picture signal generators or two or more picture reproducers
• CPC Class Codes: H04N 1/628 Memory colours, e.g. skin or sky
• CPC Class Codes: H04N 5/20 Circuitry for controlling amplitude response
• CPC Class Codes: H04N 9/643 Hue control means, e.g. flesh tone control
• CPC Class Codes: H04N 9/67 for matrixing camera processing pipelines for matrixing of colour signals H04N23/85
• CPC Class Codes: H04N 9/68 for controlling the amplitude of colour signals, e.g. automatic chroma control circuits H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86

Abstract

Techniques related to color matching and color conversion are discussed. Such techniques may include determining operators for converting input pixel values to output pixel values in a color space such that the operators may include a set of color conversion matrix operators, a chroma adaptation operator, and/or a luma adaptation operators determined based on one or more perceptual color space values associated with the input pixel values.

Claims

1. A method for performing color conversion comprising:

generating a perceptual color space value associated with an input pixel of input image data in a first color space;

determining, for the input pixel, one or more operators for converting input pixel values associated with the input pixel to output pixel values, wherein the operators comprise at least a selected color conversion matrix operator from a set of predetermined color conversion matrix operators, wherein the selected color conversion matrix operator is determined based at least in part on the perceptual color space value associated with the input pixel; and

applying the one or more operators to the input pixel values in the first color space to generate the output pixel values, wherein output image data in the first color space comprises the output pixel values.

2. The method of claim 1, wherein the first color space comprises a red green blue (RGB) color space and the perceptual color space value comprises a hue value of a hue chroma luma (HCL) color space.

3. The method of claim 1, wherein the set of predetermined color conversion matrix operators comprises color correction matrices each associated with a sector of a hue chroma plane of a hue chroma luma (HCL) color space.

4. The method of claim 3, wherein the color correction matrices are continuous over segments in the first color space.

5. The method of claim 1, wherein the one or more operators further comprise a chroma adaptation operator and a luma adaptation operator.

6. The method of claim 1, wherein the one or more operators further comprise a chroma adaptation operator to apply a chroma factor to intermediate pixel values associated with the input pixel values without affecting a luma or a hue of the intermediate input pixel values.

7. The method of claim 6, further comprising:

determining the chroma factor from a set of predetermined chroma factors based on a chroma value and a luma value associated with at least one of the input pixel values or the intermediate pixel values.

8. The method of claim 1, wherein the one or more operators further comprise a luma adaptation operator to apply a luma factor to intermediate pixel values associated with the input pixel values without affecting a chroma or a hue of the intermediate pixel values.

9. The method of claim 8, further comprising:

determining the luma factor from a set of predetermined luma factors based on a chroma value and a luma value associated with at least one of the input pixel values or the intermediate pixel values.

10. The method of claim 1, wherein the first color space comprises a red green blue (RGB) color space and the perceptual color space value comprises a hue value of a hue chroma luma (HCL) color space, and wherein the one or more operators further comprise a chroma adaptation operator to apply a chroma factor to intermediate pixel values associated with the input pixel value without affecting a luma or a hue of the input pixel value and a luma adaptation operator to apply a luma factor to the intermediate pixel value without affecting a chroma or the hue of the input pixel value.

11. The method of claim 10, further comprising:

dividing the first color space into a plurality of slices;

defining input calibration vectors for a first slice of the plurality of slices in a perceptual color space;

generating output calibration vectors for the first slice in the perceptual color space;

converting the input and output calibration vectors in the perceptual color space to a mapping in the first color space; and

generating a first color conversion matrix operator of the set of predetermined color conversion matrix operators based on the mapping in the first color space.

12. A system for performing color conversion comprising:

a memory configured to receive input image data in a first color space; and

an image processing unit coupled to the memory, the image processing unit to generate a perceptual color space value associated with an input pixel of the input image data, to determine, for the input pixel, one or more operators to convert input pixel values associated with the input pixel to output pixel values, wherein the operators comprise at least a selected color conversion matrix operator from a set of predetermined color conversion matrix operators and the selected color conversion matrix operator is determined based at least in part on the perceptual color space value associated with the input pixel, and to apply the one or more operators to the input pixel values in the first color space to generate the output pixel values, wherein output image data in the first color space comprises the output pixel values.

13. The system of claim 12, wherein the first color space comprises a red green blue (RGB) color space and the perceptual color space value comprises a hue value of a hue chroma luma (HCL) color space.

14. The system of claim 12, wherein the set of predetermined color conversion matrix operators comprises color correction matrices each associated with a sector of a hue chroma plane of a hue chroma luma (HCL) color space.

15. The system of claim 12, wherein the one or more operators further comprise a chroma adaptation operator and a luma adaptation operator.

16. The system of claim 12, wherein the one or more operators further comprise a chroma adaptation operator to apply a chroma factor to intermediate pixel values associated with the input pixel values without affecting a luma or a hue of the intermediate pixel values, and wherein the image processing unit is further to determine the chroma factor from a set of predetermined chroma factors based on a chroma value and a luma value associated with at least one of the input pixel values or the intermediate pixel values.

17. The system of claim 12, wherein the one or more operators further comprise a luma adaptation operator to apply a luma factor to intermediate pixel values associated with the input pixel values without affecting a chroma or a hue of the intermediate pixel values, and wherein the image processing unit is further to determine the luma factor from a set of predetermined luma factors based on a chroma value and a luma value associated with at least one of the input pixel values or the intermediate pixel values.

18. The system of claim 12, wherein the first color space comprises a red green blue (RGB) color space and the perceptual color space value comprises a hue value of a hue chroma luma (HCL) color space, and wherein the one or more operators further comprise a chroma adaptation operator to apply a chroma factor to intermediate pixel values associated with the input pixel values without affecting a luma or a hue of the intermediate pixel values and a luma adaptation operator to apply a luma factor to the intermediate pixel values without affecting a chroma or the hue of the intermediate pixel values.

19. At least one machine readable medium comprising a plurality of instructions that, in response to being executed on a device, cause the device to perform color conversion by:

generating a perceptual color space value associated with an input pixel of input image data in a first color space;

determining, for the input pixel, one or more operators for converting input pixel values associated with the input pixel to output pixel values, wherein the operators comprise at least a selected color conversion matrix operator from a set of predetermined color conversion matrix operators, wherein the selected color conversion matrix operator is determined based at least in part on the perceptual color space value associated with the input pixel; and

applying the one or more operators to the input pixel values in the first color space to generate the output pixel values, wherein output image data in the first color space comprises the output pixel values.

20. The machine readable medium of claim 19, wherein the first color space comprises a red green blue (RGB) color space and the perceptual color space value comprises a hue value of a hue chroma luma (HCL) color space.

21. The machine readable medium of claim 19, wherein the set of predetermined color conversion matrix operators comprises color correction matrices each associated with a sector of a hue chroma plane of a hue chroma luma (HCL) color space, wherein the color correction matrices are continuous over segments in the first color space.

22. The machine readable medium of claim 19, wherein the one or more operators further comprise a chroma adaptation operator to apply a chroma factor to intermediate pixel values associated with the input pixel values without affecting a luma or a hue of intermediate pixel values, the machine readable medium comprising further instructions that, in response to being executed on the device, cause the device to perform color conversion by:

determining the chroma factor from a set of predetermined chroma factors based on a chroma value and a luma value associated with at least one of the input pixel values or the intermediate pixel values.

23. The machine readable medium of claim 19, wherein the one or more operators further comprise a luma adaptation operator to apply a luma factor to intermediate pixel values associated with the input pixel values without affecting a chroma or a hue of the intermediate pixel values, the machine readable medium comprising further instructions that, in response to being executed on the device, cause the device to perform color conversion by:

determining the luma factor from a set of predetermined luma factors based on a chroma value and a luma value associated with at least one of the input pixel values or the intermediate pixel values.

24. The machine readable medium of claim 19, the machine readable medium comprising further instructions that, in response to being executed on the device, cause the device to perform color conversion by:

dividing the first color space into a plurality of slices;

defining input calibration vectors for a first slice of the plurality of slices in a perceptual color space;

generating output calibration vectors for the first slice in the perceptual color space;

converting the input and output calibration vectors in the perceptual color space to a mapping in the first color space; and

generating a first color conversion matrix operator of the set of predetermined color conversion matrix operators based on the mapping in the first color space.