Showing some plant detailing obscured under green paint

[eggyk]

It's pareidolia, trust me. It happens a lot with this type of tool. When something is really there, it's really quite obvious. You will see such things all over the page, and its often deformations in the parchment, general unevenness, or simply a part where the contrast blurs into apparent patterns which aren't there.

This is why I only tried the contrast enhancement once and You are not allowed to view links. Register or Login to view.. There is really no way of telling if the lines under the paint that it shows is actual ink or some artificial threshold computed from paint gradients. If some ink blobs turn into a semblance of a signature, some paint irregularities can easily turn into a resemblance of deliberate ink lines. 

Uniform models that process all the pixels in the same way and do not use spacial information are much more reliable for this, but the results don't look as spectacular.

Well, the ink blobs don't turn into any sort of signature imo. I find it very difficult to believe that these results are simply the result of paint lines. In your example the issue seemed to be lines generated from the thresholds/outlines between areas of very dark ink and the blank parchment, whereas this is highlighting slightly darker areas within an area of ink. 

For example, You are not allowed to view links. Register or Login to view. shows a middle stem on each leaf, including the leaf behind each, where the stem is visible through the leaf spikes. I think that it would be a very big coincidence if paint lines had created the same type of stem, at the same scale, on both front leaves. And these lines aren't invisible on the regular scans either; if you zoom in and look in detail at the examples I posted you can actually make out these lines.

   

Of course, using such processing to display entire pages would be entirely inappropriate. What might work best for one area of the page may not work for another, and what might work on one colour of ink may not work work well on another.

There's a world where i'm tempted to make a composite image of each page, using different processing techniques for each aspect, or even re-imposing the processed areas back on to the original image.. but this would need to have disclaimers all over it and would only be useful for illustrative purposes. Something like this below, but done far better and with more care: