Imagesc plot (dividing the colorbar to blue-green, white, and green-red range)

Question

Ronaldo 2014-5-8

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/128899-imagesc-plot-dividing-the-colorbar-to-blue-green-white-and-green-red-range

评论： Image Analyst 2014-5-10

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I want to plot the values of a matrix ranging from -10 to 10 in a way that I can assign

1) Dark blue color to * green * to the values between -10 and -5

2) White color to values between -5 and 5

3) * Green * to dark red to values between 5 and 10

It is important that I do not like to miss any color in the range of white; i.e., step 3 must begin with the color that step 1 ends with.

I could write the following which is able to plot values of a matrix which are zero or positive and assign green to red color to values larger than 0.

A=[9 9.1 8.3 0 0;

0 9.5 8.4 0 0;

0 0 9.6 8.3 8.1;

0 7.1 7 9.7 0];

lowestValue = min(A(A(:)>0))

highestValue = max(A(:))

imagesc(A);

cmap = jet(256);

colormap(cmap(120:256,:));

caxis(gca,[lowestValue-2/256, highestValue]);

for i=1:120

cmap(i,:)=[1,1,1];

end

colormap(cmap(120:256,:))

colorbar

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Answer 1

Image Analyst 2014-5-10

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/128899-imagesc-plot-dividing-the-colorbar-to-blue-green-white-and-green-red-range#answer_136285

Do you have a question? I mean other than how do I format my code properly? And if you wanted a colormap like you said, why did you use jet(256)? And did you know that i does not appear in your loop anywhere so you're just setting the same row #120 over and over again 120 times?

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Ronaldo 2014-5-10

So many thanks for your reply.I am not expert at MATLAB so maybe my code is not correct.I will delete the code if you think that it misleads others. For me it is only important to be able to plot the following.

I want to plot the values of a matrix ranging from -10 to 10 in a way that I can assign

1) Dark blue color to * green * to the values between -10 and -5

2) White color to values between -5 and 5

3) * Green * to dark red to values between 5 and 10

It is important that I do not like to miss any color in the range of white; i.e., step 3 must begin with the color that step 1 ends with.