convert matrix to rgb

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Philipp
Philipp 2012-8-6
评论： DGM 2023-1-15
dear matlab developers,
i have a double matrix (MxN). is there a way to convert it to RGB?
when i use imagesc(matrix), all the values are color coded and displayed, but is there a way to write the RGB values into a new array (MxNx3)?
br philipp

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采纳的回答

Matt Fig
Matt Fig 2012-8-6
I wonder if this is what you mean, Philipp?
% Say this is the given matrix:
G = rand(10,10)*300 - 100;
% Use IMAGESC to plot G.
figure('pos',[100 100 1000 800]);
% colormap(copper) % You realize this affects final image (H)?
subplot(1,2,1)
imagesc(G);
title('IMAGESC (MxN)')
% Now make an RGB image that matches display from IMAGESC:
C = colormap; % Get the figure's colormap.
L = size(C,1);
% Scale the matrix to the range of the map.
Gs = round(interp1(linspace(min(G(:)),max(G(:)),L),1:L,G));
H = reshape(C(Gs,:),[size(Gs) 3]); % Make RGB image from scaled.
subplot(1,2,2)
image(H) % Does this image match the other one?
title('IMAGE (MxNx3)')
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Mathieu
Mathieu 2015-8-12
Thank you so Much Matt, very helpful!!
DGM
DGM 2023-1-15
Ran in:
You could also use ind2rgb() with the desired colortable.
% create a 2D array that's not in standard image data scale
myarray = repmat(linspace(-1,1,200),[100,1]);
% create whatever color table
CT = jet(256);
% rescale to index range (multiple ways to do this)
%scaledpict = round(rescale(double(myarray),1,size(CT,1))); % R2017b+
%scaledpict = gray2ind(mat2gray(myarray),size(CT,1)); % IPT
scaledpict = round(1 + mat2gray(myarray)*(size(CT,1)-1));
% convert to RGB
outpict = ind2rgb(scaledpict,CT);
% display it
imshow(outpict)
% or save it
imwrite(outpict,'mypicture.png')

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更多回答（3 个）

Jurgen
Jurgen 2013-5-1
The FEX has mat2im and real2rgb. Can recommend both!
real2rgb
mat2im
double2rgb
Image Analyst
Image Analyst 2012-8-6
rgbImage = cat(3, redChannel, greenChannel, blueChannel);
Cast to uint8 if you want to display or save to a file. Scale to 0-255 if it's not already in that range. mat2gray() might help.
Walter Roberson
Walter Roberson 2012-8-6

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