[sane-devel] grey 4bit/pixel
hennebry at web.cs.ndsu.nodak.edu
Sat Aug 19 18:33:04 UTC 2006
On Sat, 19 Aug 2006, abel deuring wrote:
> Shashi Kumar M.S. wrote:
> > iam searching a scanner that supports at about 300 dpi and 4 bit /pixel grey
> > scanner. i found from the scanner that most of the scanner support 8/16 bit
> > depth in grey mode.
> > is there any way to modify this code to support 4 bit grey scale depth per pixel.
Why? What constitutes a good answer might depend on it.
> - look for a (documented) file format that supports 4 bit images (or
> define your own format ;)
> - patch scanimage or another frontend so that it can write the scan
> data in the format you selected. Alternatively, you can convert
> existing 8 bit images, as produced by a Sane frontend, with a
> converter program. I am not aware of any 4 bit image formats, but
> if they exist, you might already find such a converter in the
> usual Linux distributions. Otherwise, write one. The PPM, PGM, PBM
> formats (default for scanimage output) are very simple, and it is
None of those formats support 4-bit data.
They do support maxlevel=15 data, but the data are represented with 8-bits.
PBM (P4) is one bit per pixel. If you want you could stack 4 pbm images.
> quite straightforward to read them with C, Python, Perl, Java or
> whichever other programming language.
Mike hennebry at web.cs.ndsu.NoDak.edu
"it stands to reason that they weren't always called the ancients."
-- Daniel Jackson
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