How do I limit the range of a colormap when using imwrite

I want to save an image with imwrite and get the same output as the code below displays on screen

 figure,imagesc(rhoi),
 colormap(jet)
 caxis([.45*min(rhoi(:)) 0*.55*max(rhoi(:))])

Is it possible to set a caxis property for imwrite?

 imwrite(rhoi,jet,'out.png')

EDIT: I have included the full code. Basically, I want the last image RGB to look the same as that displayed by imagesc at each stage.

 clear all
 close all
 clc

 Inner = 0;     % inner radius of the colour ring
 rOuter = 150;    % outer radius of the colour ring

 [x, y] = meshgrid(-rOuter:.1:rOuter);
 [theta, rho] = cart2pol(x, y);
 rhoi=imcomplement(rho);

 cmap=jet(256);

 rhoi2=rhoi;
 rhoi2=(rhoi2-min(rhoi2(:)))/(max(rhoi2(:))-min(rhoi2(:)));
 figure;imagesc(rhoi2),colormap(cmap);
 caxis([.55 .95])

 rhoi2(rhoi2<.55) = .55;
 rhoi2(rhoi2> .95) = .95;
 figure,imagesc(rhoi2)
 colormap( cmap);

 X=uint8(256*rhoi2);
 figure;imagesc(X),colormap( cmap);

 RGB=ind2rgb(X,cmap);
 figure;imshow(RGB)

[Guillaume]

Can you confirm that your rhoi matrix is made of positive integers only. Otherwise, attempting to write an indexed image as per your imwrite call makes no sense.

[Michael Devereux]

I am scaling the matrix to a range of 0-255 and changing the range accordingly

[Michael Devereux]

I have added the full code to demonstrate the problem

Answer 1

[Guillaume]

Before the call to ind2rgb (or imwrite), you need to rescale your matrix as colour indices so that the minimum is index 1 (for type double, 0 for type uint8) and maximum is index 256 (255 for uint8):

X = round(1 + (rhoi2 - min(rhoi2(:))) * 255 / (max(rhoi2(:)) - min(rhoi2(:))));  %using double
RGB = ind2rgb(X, cmap);
figure; imshow(RGB);

[Michael Devereux]

Thanks! This did what I need.

Answer 2

[Ahmet Cecen]

You should get the same effect if you just did:

rhoi(rhoi<.45*min(rhoi(:))) = .45*min(rhoi(:));
rhoi(rhoi> 0.55*max(rhoi(:)) = 0.55*max(rhoi(:));

[Michael Devereux]

Thanks! This works for viewing with imagesc without specifying caxis but does not work with imwrite or ind2rgb.