: Linear color modification in photo and video editing I have a specific, rather obvious method of modify colors in an image in my mind, but can't find the tools in common graphic programs such

@Yeniel278

You can do this, its just not commonly done and has no builtin function for this in Photoshop or after effects at least in the gui*. Though in general color is not like a vector space and color is not stored linear (doing linear transformation on nonlinear data is a bit problematic, so first turn data linear). Also note that image editors are not floating point calculators. But yes obviously you can treat any data as a liner vector space.

Edity:

You can build a matrix transform if you wish. What you need to work on is the raw channel data. Do this in Photoshop mostly this works in any other app as well.


Duplicate layer 3 times, name the layer RED, GREEN and BLUE.


For each layer copy the respective channel to all other channels

For each channel make a Color fill layer and multiply the channel by that has the new basis that you want as a color.





Change the multiply layers to match your matrix, so if you had matrix:

1 0 0

0 0.5 0.5

0 0.75 0.5

Then enter values 255 0 0 for the red mask and 0 128 128 for green mask and 0 191 128 for blue mask. Now before you do this if you want the transform to be sane make sure you use a linear working space. And thsi is what you get:




If you need to be able to use negative values then you need to use channel mixer 3 times. Or 6 layers...

A more exotic transom could be [0 0 1 1 0 0 0 1 0] or swapping of channels:



Oh and image is from Public Domain Pictures

* color profiles have this tool. But how to construct one that is a question for stack exchange or computer graphics.

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