Lua Imageprocessing: Extracting colors

[meino.cramer@...]

Hi,

is there any lua image processing library / tool / etc. to extract
all colors from an (not necessarily indexed) image, sort the color
by either hue, saturation or value and generate another image with 
all these colors lists?

Since I may have to rearrange the colors in the output I want that 
in lua code.

Is there any such program?

Thank you very much in advance for any help!

Have a nice weekend!
Best regards,
mcc