>> Maybe a conversion filter that makes RGB->Lab and Lab->RGB,
>> available for users (and their scripts) would be helpful.
You can already decompose an image to LAB, work on the greyscale
representations of each channel, then re-compose. This is what I have
done when working in LAB space with scripts. There is a loss of data
due to the 8 bit quantization in the conversion each way, but
sometimes this is still better than nothing.
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