creating a color block inside a colormap? - homework

For one part I need to create two 3 x 3 matrices and use subplot to display a colormap that shows a single color box/rectangle in the middle of the colormap. The two would have different colors.

For example, one would be completely blue except of a red square in the center of the color map. The second one could be light blue, with the red block in the center. ???

Answer 1

[Image Analyst]

Try this:

matrix1 = [0,0,0;0,1,0;0,0,0]
matrix2 = [2,2,2;2,1,2;2,2,2]

subplot(1,2,1);
imshow(matrix1, [0,2], 'InitialMagnification', 1000);
myColorMap = [0,0,1;... % Blue
  1,0,0;...  % Red
  .5, .5, 1] % Light blue.
colorbar;

subplot(1,2,2);
imshow(matrix2, [0,2], 'InitialMagnification', 1000);

myColorMap = [0,0,1;... % Blue
  1,0,0;...  % Red
  .5, .5, 1] % Light blue.
colormap(myColorMap);
colorbar;

[Nora]

Yes that helped. Thank you!

Answer 2

[Walter Roberson]

colormaps are N x 3 vectors, with N being the number of colors and 3 representing RGB. The only way they could be square would be if you only had 3 colors. A colormap does not have colors within it: it gives the information about what RGB corresponds to which color number.