On 29/03/2010 20:40, Ian Zimmerman wrote:
Package: dcraw
Version: 8.86-1
Severity: normal
According to the manpage, dcraw -4 should write 16-bit samples. But:
[21]matica:raw$ dcraw -4 imgp0511.pef
[22]matica:raw$ gm identify imgp0511.ppm
imgp0511.ppm PNM 3040x2024+0+0 DirectClass 8-bit 35.2M 0.000u 0:01
[23]matica:raw$
GraphicsMagick does not support 16 bit PPM files.
In the example below, crw_2100_16.ppm has been converted with -4,
crw_2100.ppm has not:
$ head -3 *
==> crw_2100_16.ppm <==
P6
3088 2056
65535
==> crw_2100.ppm <==
P6
3088 2056
255
The last number identifies the maximum colour value (Maxval) indicating
that crw_2100_16.ppm is indeed 16 bit, crw_2100.ppm and is not. See:
http://netpbm.sourceforge.net/doc/ppm.html
or
ppm(5)
crw_2100_16.ppm is also twice the size of crw_2100.ppm which might have
been a clue....
-rw-rw-r-- 1 steve users 38093587 2010-03-29 23:07 crw_2100_16.ppm
-rw-rw-r-- 1 steve users 19046801 2010-03-29 23:17 crw_2100.ppm
If you wish to email me the .pef file, I will take a look at it for you.
It may be that some raw image formats are only 8 bits per colour, so
dcraw will only convert to an 8 bit ppm file. However my crw files are
10 bits per colour, so are properly converted.
GraphicsMagick display will not display 16 bit ppms, and I am fairly
sure that it cannot edit them either. Neither can the version of gimp I
have. You can use eog(1) to view them, but I believe it flattens them.
Also I am not sure what video hardware supports more than 8 bits per
colour, except some nvidia cards.
If you don't mind I will close the bug.
Regards,
--
Steve King
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