如何将颜色名称转换为3元素RGB向量? [英] How can I convert a color name to a 3 element RGB vector?

问题描述

在许多MATLAB绘图函数中，您可以将颜色指定为字符串或直接列出红色，绿色和蓝色值的3元素向量.

In many MATLAB plotting functions, you can specify the color as either a string or as a 3 element vector that directly lists the red, green, and blue values.

例如，这两个语句是等效的:

For instance, these two statements are equivalent:

plot(x, y, 'Color', 'r');
plot(x, y, 'Color', [1 0 0]);

可以通过字符串值'r','g','b','c','m','y','k','w'指定8种颜色.是否有MATLAB内置函数将这些字符串转换为等效的RGB向量?

There are 8 colors that can be specified by a string value: 'r','g','b','c','m','y','k','w'. Is there a MATLAB built-in function that converts these strings to an equivalent RGB vector?

推荐答案

我在 MathWorks File Exchange 甚至可以处理除MATLAB中的默认8以外的颜色字符串:

I found this general alternative on the MathWorks File Exchange which will even handle color strings other than the default 8 in MATLAB:

• rgb.m 由如果您只关心默认的8种颜色字符串的转换，这是我编写的一个函数，用于在RGB三元组和简短的颜色名称(即单个字符)之间来回转换:

  If you're only concerned with conversions for the default 8 color strings, here's a function I wrote myself that I use to convert back and forth between RGB triples and short color names (i.e. single characters):

  function outColor = convert_color(inColor)
  
    charValues = 'rgbcmywk'.';  %#'
    rgbValues = [eye(3); 1-eye(3); 1 1 1; 0 0 0];
    assert(~isempty(inColor),'convert_color:badInputSize',...
           'Input argument must not be empty.');
  
    if ischar(inColor)  %# Input is a character string
  
      [isColor,colorIndex] = ismember(inColor(:),charValues);
      assert(all(isColor),'convert_color:badInputContents',...
             'String input can only contain the characters ''rgbcmywk''.');
      outColor = rgbValues(colorIndex,:);
  
    elseif isnumeric(inColor) || islogical(inColor)  %# Input is a numeric or
                                                     %#   logical array
      assert(size(inColor,2) == 3,'convert_color:badInputSize',...
             'Numeric input must be an N-by-3 matrix');
      inColor = double(inColor);           %# Convert input to type double
      scaleIndex = max(inColor,[],2) > 1;  %# Find rows with values > 1
      inColor(scaleIndex,:) = inColor(scaleIndex,:)./255;  %# Scale by 255
      [isColor,colorIndex] = ismember(inColor,rgbValues,'rows');
      assert(all(isColor),'convert_color:badInputContents',...
             'RGB input must define one of the colors ''rgbcmywk''.');
      outColor = charValues(colorIndex(:));
  
    else  %# Input is an invalid type
  
      error('convert_color:badInputType',...
            'Input must be a character or numeric array.');
  
    end
  

  请注意，此函数允许您输入字符串或 N-by-3数字或逻辑数组(RGB值从0到1或0到255)，并返回相反的颜色表示.它还使用功能 ISMEMBER 进行转换.

  Note that this function allows you to input either a string of characters or an N-by-3 numeric or logical array (with RGB values from 0 to 1 or 0 to 255) and it returns the opposite color representation. It also uses the function ISMEMBER to do the conversions.

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