[sane-devel] sp15c - 4 Bit gray generates 8 bit files

Henning Meier-Geinitz henning@meier-geinitz.de
Sun, 3 Jul 2005 16:38:13 +0200


On Sun, Jul 03, 2005 at 05:03:52AM -0400, Gregory C. Johnson wrote:
> Does SANE require grayscale to be 8 BPP, or am I just completely missing
> why one would want to shift 4 bits of information into the most
> significant bits of twice as many bytes?

Quote from the SANE standard (3.2): "Valid bit depths are 1, 8, or 16
bits per sample. If a device's natural bit depth is something else, it
is up to the driver to scale the sample values appropriately (e.g., a
4 bit sample could be scaled by a factor of four to represent a sample
value of depth 8)."