Question

I have a filter of size 150 by 150 When using imagesc to plot the filter, the background is green

minValue = -1.5; maxValue = +1.5;

The RGB index of zeros in the image (green color) is is 0.5,1,0.5

I would like to change all the index ‘0’ / background colour in the image to white while leaving the remaining as they are if possible.

size(colormap) : 64 3

I have tried the following but it does not seem to work on my image:
matlab's imagesc background color

Thanks a lot

Answer 1

Here’s my solution. Histogram image intensities, find those that are closest to zero, then set it to white. For example:

 m=peaks(100); % generate data
 imagesc(m);   

 colormap_range=64; % default colormap_range is 64, but change it to your needs
 [n,xout] =hist(m(:),colormap_range);   % hist intensities according to the colormap range
 [val ind]=sort(abs(xout)); % sort according to values closest to zero
 j = jet;
 j(ind(1),:) = [ 1 1 1 ]; % also see comment below
 % you can also use instead something like j(ind(1:whatever),:)=ones(whatever,3); 
 colormap(j);

instead of sort you can use min, but I thought that by sorting you can also edit more than just that level with additional lines such as, j(ind(1:3),:)=ones(3); . The attached figure below was done using this…