which colormap I can chose to draw these figures?

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

Answer 1

[DGM]

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.

[Ahmed]

Thank you, the last one is much closer.

Answer 2

[Image Analyst]

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];

[Ahmed]

@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.