Match altered image to its original

[Brian.Raila]

Objective is to match an image altered by an uncontrollable process, to a variant which will, when run through that same process, appear the same as in its original, unprocessed form.

I have reviewed numerous posts, tutorials, etc., but remain stumped.

1. I have no control over that process/processor, which let's say imparts a "ghost image" of whatever runs through it.
   
2. I must run through that process/processor, and cannot side-step it.
   
3. My hunch is it has something to do with legacy engineering, such as conversion from 24-bit to 16-bit color, or along those lines.
   

Attached is '1 Hall Original.png', which is the intended appearance to the user.

Attached '2 Hall Ghosted.png' indicates the "ghosting" which is beyond my control.

I seek to create an image, 'Hall Original - Prepped for Ghosting', which will come out the other end appearing identical to the pre-processed original.

Attached '9 Image A - Gray of RGBs 119 on L, Ghosted to RGBs 137 on R' was successfully addressed by setting Image A to Brightness -34 [resulting in RGBs of 103].  Post-process, it measures all 119s.

However, the ghost processor is provably not simply linear, across all channels, as seen in the more complex Hall image, as it is not similarly remedied by simply a Brightness reduction.  (If twiddling only Brightness, approximate matches are: Stage -6, Back wall -12, Center red carpet -33.)

I am aware of Color Curves, Channels, and such, but fully inexpert in their application.

[Disclaimer: I'm aware of spatial distortions regarding slight scaling/proportionality differences in the examples.  That is easily remedied by a more careful workflow that shall be employed.  Not to worry.]

.....  I see I hit the 5-file Upload Limit.  Shall send specimens 6 - 9 in followup to this Post .....

Prompt replies would be most gratefully welcomed.

Thanks,

BR

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Find here attached, specimens 6 - 9 mentioned in my original Post.

– BR