which colormap I can chose to draw these figures?

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Which colormap I can use to plot following figures? or any unction or code to create following figures by using imagesc?

Accepted Answer

DGM
DGM on 8 Feb 2024
Edited: DGM on 8 Feb 2024
Attached are colormap generators that attempts to make something close to the given colormaps. It's only a blind approximation, but it's closer. The three images don't use the same colormap, so here are three different versions. Pick one.
load SNR.mat
% the first map is a 5-point map with dark endpoints and a white center
imagesc(Snear)
colormap(bluewhitered1(256))
% the second map is a 3-point map with bright endpoints and a white center
figure
imagesc(Snear)
colormap(bluewhitered2(256))
% the third map is a 5-point map with slightly dark endpoints and a gray center
figure
imagesc(Snear)
colormap(bluewhitered3(256))
Bear in mind that there isn't a way to back-calculate the colormap from the image alone. The progression is all guesswork, and the rest is just PWL interpolation in RGB based on those guesses and a sampling of the provided colors.

More Answers (1)

Image Analyst
Image Analyst on 7 Feb 2024
Hard to say without knowing the data values but it looks like a ramp of red and an inverse ramp of blue with white in the middle. Maybe try something like
numColors = 256;
triangle = [linspace(0, 1, numColors/2)'; linspace(1, 0, numColors/2)'];
r = triangle;
g = triangle;
b = triangle;
r(numColors/2 + 1 : end) = 1;
b(1 : numColors/2) = 1;
plot(r, 'r-', 'LineWidth', 3);
hold on;
plot(g, 'g-', 'LineWidth', 3);
plot(b, 'b-', 'LineWidth', 3);
title("Custom Color Map")
grid on;
% Make the colormap
cmap = [r, g, b];
  1 Comment
Ahmed
Ahmed on 7 Feb 2024
Edited: Walter Roberson on 7 Feb 2024
@Image Analyst data is plotted as, for example,
ntr = 227;
t = 116 * 1 size
Snear = 116 * 227 Size
(i.e. crest and trough)
figure, imagesc([1:ntr], t, Snear)
The data for the first figure is attached here as SNR.mat, only have Snear.

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