颜色

颜色空间转换，支持国际色彩联盟 (ICC) 配置文件

该工具箱将颜色表示为 RGB 值，但除了 RGB 之外，还有其他一些以数值形式表示颜色的模型。之所以存在各种颜色空间，是因为它们表达颜色信息时所采用的方法可使某些计算更为便捷，或是因为它们提供了更为直观的颜色辨识方法。工具箱提供将颜色数据从一个颜色空间转换到另一个颜色空间的函数。工具箱还支持通过国际色彩联盟 (ICC) 配置文件来描述颜色。

函数

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颜色空间转换

`rgb2hsv`	将 RGB 颜色转换为 HSV
`rgb2lab`	将 RGB 转换为 CIE 1976 Lab*
`rgb2ntsc`	Convert RGB color values to NTSC color space
`rgb2xyz`	Convert RGB to CIE 1931 XYZ
`rgb2ycbcr`	将 RGB 颜色值转换为 YCbCr 颜色空间
`rgbwide2ycbcr`	Convert wide-gamut RGB color values to YCbCr color values
`rgbwide2xyz`	Convert wide-gamut RGB color values to CIE 1931 XYZ color values
`hsv2rgb`	将 HSV 颜色转换为 RGB
`lab2rgb`	Convert CIE 1976 Lab* to RGB
`lab2xyz`	Convert CIE 1976 Lab* to CIE 1931 XYZ
`ntsc2rgb`	Convert NTSC values to RGB color space
`xyz2lab`	Convert CIE 1931 XYZ to CIE 1976 Lab*
`xyz2rgb`	Convert CIE 1931 XYZ to RGB
`xyz2rgbwide`	Convert CIE 1931 XYZ color values to wide-gamut RGB color values
`ycbcr2rgb`	Convert YCbCr color values to RGB color space
`ycbcr2rgbwide`	Convert YCbCr color values to wide-gamut RGB color values
`colorcloud`	Display 3-D color gamut as point cloud in specified color space

颜色值到数据类型的转换

`lab2double`	Convert Lab* color values to `double`
`lab2uint16`	Convert Lab color values to `uint16`
`lab2uint8`	Convert Lab color values to `uint8`
`xyz2double`	Convert XYZ color values to `double`
`xyz2uint16`	Convert XYZ color values to `uint16`

国际色彩联盟 (ICC) 配置文件

`iccfind`	Find ICC profiles
`iccread`	Read ICC profile
`iccroot`	Find system default ICC profile repository
`iccwrite`	Write ICC color profile data
`isicc`	Check for valid ICC profile data

颜色变换

`makecform`	Create color transformation structure
`applycform`	Apply device-independent color space transformation
`imapprox`	通过减少颜色数量来近似处理索引图像

自动白平衡

`chromadapt`	Adjust color balance of RGB image with chromatic adaptation
`illumgray`	Estimate illuminant using gray world algorithm
`illumpca`	Estimate illuminant using principal component analysis (PCA)
`illumwhite`	Estimate illuminant using White Patch Retinex algorithm
`lin2rgb`	Apply gamma correction to linear RGB values
`rgb2lin`	Linearize gamma-corrected RGB values
`whitepoint`	XYZ color values of standard illuminants

测量颜色差异

`colorangle`	Angle between two RGB vectors
`deltaE`	Color difference based on CIE76 standard
`imcolordiff`	Color difference based on CIE94 or CIE2000 standard

主题

Understanding Color Spaces and Color Space Conversion

A color space maps a color in a multidimensional coordinate system. Color spaces have different advantages in identifying colors or performing calculations.

Device-Independent Color Spaces

Device-independent color spaces define a standardized color space where three values represent a color. Different standards exist for many applications of color display.

Profile-Based Color Space Conversions

Device profiles contain information about how input, output, and display devices reproduce colors. Convert the color space so displayed colors look the same across all devices.

Display Colors

The bit depth of a screen display defines how many distinct colors the display can produce. You can determine and change the screen bit depth of your system.

Reduce the Number of Colors in an Image

Learn how to reduce the number of colors in an image using color approximation or dithering.

特色示例

Convert Between RGB and HSV Color Spaces

Adjust the saturation of a color image by converting the image to the HSV color space. The example then displays the separate HSV color planes (hue, saturation, and value) of a synthetic image.

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Determine If Lab* Value Is in RGB Gamut

Use color space conversion to determine if an L*a*b* value is in the RGB gamut.

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Calculate CIE94 Color Difference of Colors on Test Chart

Calculate the color difference of measured and reference colors using the CIE94 standard. By default, the measureColor function calculates the color difference between measured and reference colors on a test chart using the CIE76 standard. You can use the imcolordiff function to calculate the color difference using the CIE94 or CIEDE2000 standard.

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Comparison of Auto White Balance Algorithms

Estimate illumination and perform white balance of a scene using three different illumination algorithms. The example compares the estimated illuminant to a ground truth illuminant calculated using an X-Rite® ColorChecker® chart.

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