Stewart Robert Hinsley schreef
I was under the impression that the problem was with the originals; the
19th century documents on Gallica are mostly a lot more readable than
the 18th century ones.
--
Stewart Robert Hinsley

+ + +
It is hard to say. I have not seen all that many, but what I saw of the
Flora Brasiliensis was pretty bad too. My impression is that it has to do
with the settings of the scanning equipment. To do it right you have to
adjust for the paper, which is different for every book. I rather suspect
that this fiddling around with the settings is not consistently done every
time a new book is scanned. Obviously it will be more difficult for older
books. Maybe the older books should be photographed
rather than scanned?

For the moment I am glad that those books are accessible on the internet,
but it is nothing like having the real thing in one's hands.
PvR