Imagesc change of colors

Hello, i have a matrix like this one:

   1.0000    0.7944    0.7361    0.8205    0.4192
    0.7944    1.0000    0.8663    0.6780    0.3435
    0.7361    0.8663    1.0000    0.7351    0.3311
    0.8205    0.6780    0.7351    1.0000    0.3555
    0.4192    0.3435    0.3311    0.3555    1.0000

that is the result between the correlation of different measures.

Using imagesc i do the plot of this matrix as shown in figure:

http://imageshack.us/photo/my-images/215/72988760.jpg/

using the command caxis i set the colorbar between [-1, 1] and the colors became fuzzy. i want to know if it is possible, and how, to set for example at index a(1,2) the color that i chose and if it is possible to use/set the same color for a different value in another matrix but at the same position (always a(1,2)).

[Sven]

Salvatore, make sure you read:

Doc > Image Processing Toolbox > Introduction > Indexed Images

Then:

[newIm, colMap] = gray2ind(Im);

Will give you your colour map with a new *indexed* image.