Colormap based on contour values

Question

Tyler Smith 2017-3-3

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/327918-colormap-based-on-contour-values

评论： Tyler Smith 2017-3-3

I want to make my color map such that it uses white for the 0 value and applies a diverging ramp of color (blue and red) for cmax and cmin. The example map I have is temperature anomalies. I can go through and manually adjust the RGB values so that white is 0, but I was hoping there was an easier way to automate the process so that the 0 value in the axis range is automatically white and the values diverge from there (either toward darker blue for negative or toward darker red for positive values). Any help would be great!

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Answer 1

Guillaume 2017-3-3

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https://ww2.mathworks.cn/matlabcentral/answers/327918-colormap-based-on-contour-values#answer_257138

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function cmap = geblueredcolormap(cmin, cmax)
  assert(cmin<0 & cmax> 0, 'colormap does not cross zero');
  zeroidx = round(-cmin*255/(cmax-cmin));
  bluesat = linspace(1, 0, zeroidx);
  redsat = linspace(0, 1, 256-zeroidx);
  hsv = [repmat([0 1 1], zeroidx, 1); repmat([2/3 1 1], 255-zeroidx, 1)];
  hsv(:, 2) = [bluesat, redsat(2:end)];
  cmap = hsv2rgb(hsv);
end