Heatmap a Matrix of values

Hello,

i have a matrix of pixels A. I would like to create a heatmap on A; i mean that i want colour all the pixels in the matrix of a color. The pixels with highest values should have the darkest color, the pixels with lowest values should have a lighter colour. For example, i would use the color red, then all the biggest values in my matrix should be colored of dark red, all the lowest values should be colored of light red, so i'm interested in an interval of the colour.

Do you know how can i do that?

Thank you very much for your help.

[Adam]

What is wrong with what you get from just doing the basic:

figure; hAxes = gca;
imagesc( hAxes, myData );
colormap( hot );

[Maurizio Cimino]

Thank you very much, i'm new to matlab and i didn't know that.

[Maurizio Cimino]

Do you know if there's a way to color of blue (for example) just the negative values?

[Adam]

You can edit colourmaps in a variety of ways, but you also need to ensure you set the colourmap axis range specifically for something like that.

doc caxis

So, for example, you could use half heat map and the other half just entirely blue by doing something like:

myColourmap = [ repmat( [0 0 1], 128, 1 ); hot(128) ];

then use this colourmap:

colormap( myColourmap );

instead of 'hot' above. But then you must setup a symmetric colour axis range in order for your data to sit correctly within the colourmap e.g.

caxis( hAxes, [-1 1] * max( abs( myData ) ) )