What are look-up tables in image processing

Programming curve tool for working with RGB channels (combined)

I'm working on a curve tool and I have to adjust all three channels with a curve at the same time. (RGB curve)

Internally, the class I created for the count gets a series of control points to loop the curve through and then has a method that returns the resulting value for a given input (and also a look-up table - a table that basically tells me that for pixels with a RED intensity set to 50, that intensity should be set to 150 for each intensity (0-255] - 8-bit channels).

Now I can get a channel (for example, RED) from an RGB image and apply the look-up table to it, and I can do it separately, but I don't know which application method to use for all three channels?

I think I'll apply the LUT (look-up table) three times - once on each of the channels, but I'm not sure it's the behavior I want. Is it right or should I use it differently? (Calculate a "median value" for each pixel, apply the LUT and calculate all three channel values ​​in reverse? Etc.)

My knowledge of photography and image processing is basically zero - apart from the programming part and basic theory.


You should apply the LUT to every channel.

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I needed confirmation on this :)