Colors appear to be added by the restoration process. This kills originality of the works. I would prefer to see an artwork as it was created, not "enhanced" in anyway.

The original scans with faded colors and yellowed paper are also available: https://www.c82.net/naturalists-library/sources/scans

The artwork "as it was created" is unavailable. The only options are Rougeoux or the ravages of time.

Incorrect.