matlab中的colormap matlab colormap函数

colormap（颜色映射）

Set and get the currentcolormap（设置或得到当前的颜色映射表）

Syntax（语法）

colormap(map)
colormap('default')
cmap = colormap

Description（描述）

A colormap is an m-by-3 matrix ofreal numbers between 0.0 and 1.0. Each row is an RGB vector thatdefines one color. The kth row of the colormap defines the kthcolor, where map(k,:) = [r(k) g(k) b(k)]) specifies the intensityof red, green, andblue.（一个颜色映射表是一个由0~1的实数组成的m*3矩阵。每一行是一个定义一种颜色的向量。第k行颜色映射表定义了第k种颜色，而map(k,:)= [r(k) g(k) b(k)] 定义了红、绿、蓝的程度）

colormap(map) sets the colormap tothe matrix map. If any values in map are outside the interval [01], MATLAB returns the error Colormap must have values in [0,1]（colormap(map)把设置颜色映射表设置为矩阵映射。如果映射的任意值超出了0~1的范围，MATLAB就会返回Colormap值必须在0~1之间的错误）

colormap('default') sets the currentcolormap to the defaultcolormap.（colormap('default')设置当前颜色映射表为缺省颜色映射表）

cmap = colormap; retrieves thecurrent colormap. The values returned are in the interval [01].（cmap = colormap是取回当前的颜色映射表，返回值必须在0~1之间）

SpecifyingColormaps（Colormaps的定义）

M-files in the color directorygenerate a number of colormaps. Each M-file accepts the colormapsize as an argument. For example,colormap(hsv(128))creates an hsvcolormap with 128 colors. If you do not specify a size, MATLABcreates a colormap the same size as the currentcolormap.（颜色目录的M文件生成一系列颜色映射。每一个M文件把colormap的大小作为一个变量，例如colormap(hsv(128)）就是创建了一个带有128种颜色的hsv映射。如果你不定义大小，MATLAB就会创建和当前颜色映射相同的颜色映射）

Supported Colormaps（支持的颜色映射）

MATLAB supports a number ofcolormaps.（matlab支持一系列颜色映射）

autumnvaries smoothly from red,through orange, toyellow.boneisa grayscale colormap with a higher value for the blue component.This colormap is useful for adding an "electronic" look tograyscale images.colorcubecontainsas many regularly spaced colors in RGB colorspace as possible,while attempting to provide more steps of gray, pure red, puregreen, and pure blue.coolconsistsof colors that are shades of cyan and magenta. It varies smoothlyfrom cyan to magenta.coppervariessmoothly from black to brightcopper.flagconsistsof the colors red, white, blue, and black. This colormap completelychanges color with each index increment. gray returns a lineargrayscale colormap.hotvariessmoothly from black through shades of red, orange, and yellow, towhite.hsvvaries the hue component of thehue-saturation-value color model. The colors begin with red, passthrough yellow, green, cyan, blue, magenta, and return to red. Thecolormap is particularly appropriate for displaying periodicfunctions. hsv(m) is the same as hsv2rgb([h ones(m,2)]) where h isthe linear ramp, h =(0:m-1)'/m.jetrangesfrom blue to red, and passes through the colors cyan, yellow, andorange. It is a variation of the hsv colormap. Thejetcolormap is associated with an astrophysical fluid jet simulationfrom the National Center for Supercomputer Applications. See the"Examples" section. lines produces a colormap of colors specifiedby the axes ColorOrder property and a shade ofgray.pinkcontainspastel shades of pink. The pink colormap provides sepia tonecolorization of grayscale photographs. prism repeats the six ————colorsred, orange, yellow, green, blue, and violet. spring consists ofcolors that are shades of magenta andyellow.summerconsistsof colors that are shades of green and yellow. white is an allwhite monochrome colormap. winter consists of colors that areshades of blue and green

Examples

The images and colormaps demo,imagedemo, provides an introduction to colormaps. Select ColorSpiral from the menu. This uses the pcolor function to display a16-by-16 matrix whose elements vary from 0 to 255 in a rectilinearspiral. The hsv colormap starts with red in the center, then passesthrough yellow, green, cyan, blue, and magenta before returning tored at the outside end of the spiral. Selecting Colormap Menu givesaccess to a number of other colormaps.

The rgbplot function plots colormapvalues. Try rgbplot(hsv), rgbplot(gray), and rgbplot(hot).

The following commands display theflujet data using the jet colormap.

load flujet
image(X)
colormap(jet)

The demos directory contains a CATscan image of a human spine. To view the image, type the followingcommands: load spine

image(X)
colormap bone

AlgorithmEach figure has its ownColormap property. colormap is an M-file that sets and gets thisproperty.