imagesc - change background colour

Hello,

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' in the image to white while leaving the remaining as they are if possible.

size(colormap) : 64 3

I have tried the following:

     imagesc(filter)
     currentMap = colormap;
     newMap = [1 1 1; currentMap];
     colormap(newMap)

% The code above applies only to the top row of the filter but instead I would like the remaining index '0' to be 1

The code below changes the background to while but this time both +ve and -ve values of the filter turn purple:

     j = colormap;
     j(:,1) = [ 1 ];
     j(:,3) = [ 1 ];
     colormap(j);
    imagesc(filter);

Looking forward to your feedback. Thanks a lot for your help.

Ash

Answer 1

[bym]

I am not sure exactly what you are asking, but is this close?

x = rand(150)*1.5-3;
imagesc(x)
cmap = colormap;
cmap_mod = cmap;
cmap_mod(any(cmap'==0),:)=1;
colormap(cmap_mod)