Image processing method, image processing apparatus, and image processing program

Patent metadata

Field	Value
Publication number	US-2016286090-A1
Application number	US-201615176457-A
Country	US
Kind code	A1
Filing date	Jun 8, 2016
Priority date	May 30, 2012
Publication date	Sep 29, 2016
Grant date	—

Abstract

In the image processing apparatus, Input transform into an input color space is performed on input image data; After the input transform, transform processing of transforming chroma or chromaticity of the input image data or chroma or chromaticity in the input color space is performed so as to reduce a difference between a space of chroma or chromaticity of the input image data and a space of chroma or chromaticity in the input color space to acquire transformed image data; and Output transform into an output color space is performed on the transformed image data using a three-dimensional lookup table including inverse transform processing of returning the chroma or chromaticity of the transformed image data to the chroma or chromaticity of the input image data to acquire output image data.

First claim

What is claimed is:

1 . An image processing method comprising:
performing input transform into an input color space, which is independent from an input device, on input image data of the input device; after the input transform, performing transform processing of transforming chroma or chromaticity of the input image data or chroma or chromaticity in the input color space so as to reduce a difference between a space of chroma or chromaticity of the input image data and a space of chroma or chromaticity in the input color space so that the space of chroma or chromaticity of the input image data effectively uses the space of chroma or chromaticity in the input color space to acquire transformed image data; performing integer encoding on the transformed image data; and performing inverse transform processing of returning the chroma or chromaticity of the transformed image data to the chroma or chromaticity of the input image data and image processing of transforming the transformed image data into an output image data of an output device by performing output transform into an output color space of the output device on the transformed image data.

2 . The image processing method according to claim 1 ,
wherein after the input transform, transform processing of increasing the chroma of the input image data is performed to acquire transformed image data, and in the output transform, inverse transform processing of decreasing an amount of chroma increased in the transformed image data to return the chroma to the chroma of the input image data and image processing of transforming the transformed image data into the output image data are performed.

3 . The image processing method according to claim 1 ,
wherein after the input transform, transform processing of transforming the input image data in the input color space into image data in a high-chroma color space in which chroma has increased with respect to the input color space is performed to acquire transformed image data and in the output transform, inverse transform processing of inversely transforming the transformed image data in the high-chroma color space into the input image data in the input color space and image processing of transforming the inversely-transformed input image data into the output image data are performed.

4 . The image processing method according to claim 1 ,
wherein after the input transform, transform processing of transforming the input image data in the input color space into image data in a first color space composed of brightness and chromaticity and transforming the first color space into a low-chromaticity color space in which the chromaticity of the first color space has decreased is performed to acquire transformed image data and in the output transform, inverse transform processing of inversely transforming the low-chromaticity color space into the first color space and inversely transforming the image data in the inversely-transformed first color space into the input image data in the input color space and image processing of transforming the inversely-transformed input image data into the output image data are performed.

5 . The image processing method according to claim 1 ,
wherein after the input transform, transform processing of transforming the input image data in the input color space into image data in a second color space composed of brightness, chroma, and hue and transforming the second color space into a low-chroma color space in which the chroma of the second color space has decreased is performed to acquire transformed image data, and in the output transform, inverse transform processing of inversely transforming the low-chroma color space into the second color space and inversely transforming the image data in the inversely-transformed second color space into the input image data in the input color space and image processing of transforming the inversely-transformed input image data into the output image data are performed.

6 . The image processing method according to claim 1 ,
wherein the output transform performs the inverse transform processing and the image processing using a three-dimensional lookup table.

7 . The image processing method according to claim 1 ,
wherein the transform processing is performed in a logarithmic color space using the input image data and the transform image data which are transformed in logarithmic values.

8 . The image processing method according to claim 1 ,
wherein the transform processing is performed using a Red, Green, and Blue matrix.

9 . The image processing method according to claim 1 ,
wherein, when the transform processing is performed, a rate of increase of chroma is changed depending on a distance of the input image data from gray in an input color space of the input image data.

10 . An image processing apparatus comprising:
an input transform processor which performs input transform into an input color space, which is independent from an input device, on input image data of the input device; a chroma/chromaticity optimizing processor which performs transform processing of transforming chroma or chromaticity of the input image data or chroma or chromaticity in the input color space so as to reduce a difference between a space of chroma or chromaticity of the input image data and a space of chroma or chromaticity in the input color space so that the space of chroma or chromaticity of the input image data effectively uses the space of chroma or chromaticity in the input color space to acquire transformed image data, after the input transform; an integer encoding processor which performs integer encoding on the transformed image data acquired by the chroma/chromaticity optimizing unit; and an output transform processor which performs output transform into an output color space of an output device on the transformed image data subjected to integer encoding by the integer encoding unit to acquire output image data of the output device, wherein in the output transform, the output transform unit performs inverse transform processing of returning the chroma or chromaticity of the transformed image data to the chroma or chromaticity of the input image data and image processing of transforming the transformed image data into the output image data.

11 . The image processing apparatus according to claim 10 ,
wherein, after the input transform, the chroma/chromaticity optimizing unit performs transform processing of increasing chroma of the input image data to acquire transformed image data, and in the output transform, the output transform unit performs inverse transform processing of decreasing the chroma of the transformed image data by an increased amount to return the chroma of the transformed image data to the chroma of the input image data and image processing of transforming the transformed image data into the output image data.

12 . The image processing apparatus according to claim 10 ,
wherein, after the input transform, the chroma/chromaticity optimizing unit performs transform processing of transforming the input image data in the input color space into image data in a high-chroma color space in which chroma has increased with respect to the input color space to acquire transformed image data, and in the output transform, the output transform unit performs inverse transform processing of inversely transforming the transformed image data in the high-chroma color space into the input image data in the input color space and image processing of transforming the inversely transformed input image data into the output image data.

13 . The image processing apparatus accordin

Assignees

• Fujifilm Corp

Inventors

• Iwaki Yasuharu
• Uchida Mitsuhiro

Classifications

• G06T11/10

  Texturing; Colouring; Generation of textures or colours (retouching, inpainting or scratch removal G06T5/77) · CPC title

• H04N1/6058 Primary

  Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut · CPC title

• H04N1/6005

  with luminance or chrominance signals, e.g. LC1C2, HSL or YUV · CPC title

• G09G5/06

  using colour palettes, e.g. look-up tables · CPC title

• G09G2340/06

  Colour space transformation · CPC title