Using HSI instead of LRGB Combination

Jeroen Moonen

Jun 17, 2014
For almost every project I use the same workflow: if I have luminance data I process that regarding contrast, detail and sharpness. After that I combine the color image with this processed luminance using LRGBCombination. If I don’t have luminance data but only RGB, I use RGBWorkingSpace to link the 3 colors at the same level and then exctract an “artificial” luminance from this color image. This artificial luminance is then processed the same way as a “normal” luminance. The idea behind this is that you don’t have to worry about chromatic noise and color balance, but only have to deal with the luminance noise.

The problem is that in some cases the LRGBCombination gives a very undersaturated result with dull colors, no matter what adjustments you make. I don’t know if this has been discussed before, but I tried another approach to this problem: split the color image into the HSI channels using ChannelExtraction, delete the I-channel and after that combine the HSI again with ChannelCombination and use the processed luminance as the I-channel. So far I’ve done 2 projects with very good results. In some cases you might want to use LinearFit using the original I-channel as a reference and adjust the luminance before combining the channels.
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