Different parchment color through Herbal section?

[Jorge_Stolfi]

Ill have more to say about this soon, but i just want to point out that the broad story here is visible without any graphs, or page sampling, in a single photo.

But beware that the darkness of each 40x40 square in that image mostly depends on how much of it is covered by the gaps between folios rater than by the vellum.  (This is the sort of thing that Claude will not understand...)

Thus, for example, the middle section is lighter because the edges of the fold-outs are broader than the edges of the single folios, so the gaps/vellum ratio is lower.

Also beware that the edges of the folios have continued to darken for the 500(?) yeras since the book was bound, even while it was sitting closed on some library shelf.

More generally, we can see that the vellum was off-cuts and third-grade material, and that the Author could not bear to trim off any bad parts.  So we cannot assume that the bifolios all had the same nice light color before they were written.  The darker color of f68r3 and f72r3 is probably "primeval" (indeed f68 and f72 may be two halves of an original sheet ~470 mm tall).  Ditto for the darker "halos" around the dents on the edges of f81r/v and f112r/v. 

For these reasons, I don't see any hope of obtaining useful information (like the order of writing, or the intended reading order) from analysis of vellum color.

All the best, --stolfi