Showing some plant detailing obscured under green paint

[eggyk]

Can you share your workflow to achieve this result? It certainly makes the ink stand out better, especially in leaf venation.

Yes, of course. For this I used a fantastic online steganography tool that I used to use for image analysis: You are not allowed to view links. Register or Login to view.

For these specific images, the exact settings are the following: 

Upload the file (as non compressed as possible, i used the full size jpgs from the yale online library)
Principal Component Analysis
Input -> Color
Component -> 2
Linearize -> Yes
Invert -> Whatever you prefer
Enhancement -> Equalize Histogram (but any option is fine)

I then pasted the images into an image program and slightly adjusted the brightness and contrast to make the details clearer depending on each image (not entirely necessary). 

I simply happened across some details by chance when looking at another page for a different reason while playing around with the tool. Once I noticed something, I decided to check with other pages too.