Making a grayscale matrix

I am trying to create a grayscale matrix.

I would like to have an M by N matrix. The gray scale is from [0 255]. I would like to be able to change the entire color of the matrix to a number matching the grayscale.

For example (1)I have a 5 by 5 matrix (2)I grayscale number to be half of [ 0 255] so 128 (3)I need the entire matrix to show the 128 color. (4)I also need to be able to change the input number from the grayscale.

How do I do this. I tried but I can't get the entire matrix to be one color.

Answer 1

[Geoff Hayes]

Perhaps I'm misunderstanding, but it seems that you are trying to just assign the same value to all elements within your matrix. For example,

 gsMtx = uint8(zeros(512,512));
 image(gsMtx);
 colormap(gray(256));

would create a black image. If we change this so that all elements of gsMtx are 128, then we would do

 gsMtx(:,:) = 128;
 image(gsMtx);
 colormap(gray(256));

which would create a gray image.