Plotting a matrix using colormap and imagesc and modifying colors

Hi,

I am trying to change the colors of my plot but I am not sure how to do that. My code is:

A=zeros(5)

A(3,3)=R5

figure

colormap('default')

imagesc(A)

I would like 0 to equal green and 3 to equal black. can i do that with these commands or are their better options out there?

Answer 1

[Geoff Hayes]

Nicole - there are probably several ways to do this, so here is one. Define your own color map as

 myColorMap = [0 1 0;
               0 0 0];

where each row is an RGB vector that defines one colour (each real number must be between 0 and 1). Note that the first row corresponds to green since we have a one in the G (green) column and zeros elsewhere. The second row corresponds to black since a zero is present in the R (first), G (second), and B (third) columns.

If your A is defined to be

 A =

     0     0     0     0     0
     0     0     0     0     0
     0     0     3     0     0
     0     0     0     0     0
     0     0     0     0     0

then to display the centre element as black and the rest as green, we set the current color map

 colormap(myColorMap);

and display your image

 imagesc(A) % or image(A)

The catch with the above is how do you map other values (not zeros or threes) in A to different colors?