User`s guide

Graphics and 3-D Visualization
16-21
Graphics and 3-D Visualization
Functions Previously Only Available in the Image Processing Toolbox
Now Available in MATLAB
The following functions have been added to MATLAB from the Image Processing Toolbox:
rgb2ind: Convert RGB image to indexed image.
dither: Convert image using dithering.
cmunique: Eliminate unneeded colors in colormap of indexed image.
cmpermute: Rearrange colors in colormap.
imapprox: Approximate indexed image by one with fewer colors.
Compatibility Considerations
The dither and imapprox functions no longer display their output as an image via
a call to imshow when called with no output arguments. Instead, the first output
argument appears in the Command Window if no semicolon ends the line.
Function rgb2ind errors when called with syntax rgb2ind(rgb).
Function imapprox errors when called with syntax imapprox(x,map).