Converting images - grayscale and color

gray_to_rgb(gray, colormap) Returns single color vector or packed grayscale matrix gray converted to a packed color matrix using color palette matrix colormap.

rgb_to_gray(RGB) Returns packed RGB color matrix RGB converted to grayscale.

Arguments:

• gray, RGB are image matrices or vectors.
• colormap is a 4-column matrix specifying grayscale intensity in the first column, and RGB values in the second through fourth columns, respectively. First column values must be real numbers between 0 and 255.

Alternatively, the functions described above can take three arguments, for example (R, G, B), where R, G, and B are scalars or matrices.