TIFF and LibTiff Mail List Archive

2000.07.05 16:08 "Recto Verso in Fujitsu series 3099x", by Yves Reynaud

We have noticed that there is a difference in the Recto Verso "sensitivity" of our scanners. Scanning the same sample page as recto and verso with the same settings: Tiff CCITT IV, 300 dpi, (default for the rest, no dither, no gamma, off for white level follow) we obtain the following results:

  1. The image recto is always more in the threshold to dark than the image verso, (it is darker than verso).
  2. The image recto file size is in consequence bigger than verso image size.

With a good printed page this is hard to recognize, but if you have mixed quality (dark/pale/pale/dark, also color print) documents, then you would find it easier to recognize, as you will rescan with different settings, e.g. what is good for recto is not always good for verso although some/many times yes.

The lamps were changed/interchanged, the results are the same. Maintenance of scanners have been always regular. There is no special light in the room and this effect is the same at any hour of the day or night.

We have spoken with the representative maintenance technicians, and the answer is that most probably all the scanners have the same "irregularity".

Any tips?

Yves Reynaud
Senior Imaging Technician, INIS Clearinghouse
International Atomic Energy Agency
Wagramer Strasse 5
P.O. Box 100
A-1400 Vienna, Austria
Phone: +43 1 2600 22878
Fax: +43 1 2600 29882