Pareidolia, but underwater: What is under the green paint?

[ReneZ]

I have been trying off and on over the years to 'detect' ink under the paint, by processing the images.

The case without paint is already difficult. This is because the basic hue of the parchment and the ink is relatively close. This is also visible from the color cubes shown in one of the earlier posts, as the two lines are roughly each other's extensions. All one has to go by is the lightness.

When there is (say) green paint, at least we have a hue difference, but dark paint is still very hard to distinguish from paint over ink. At least using standard approaches. AI-based approaches should have a better chance here.

However, in all cases I had to conclude that the human eye and brain together are the best tool to recognise things. Using image processing to enhance the image in whatever way, rarely ever brought anything that wasn't already somehow visible and used by the brain. (But at the same time lots of stuff that was meaningless).