For anyone who might be interested, I would like to share some of my
experience about "dcraw".
If you like photography and have been used any DSLR/CSC, you might be
familiar with the "RAW" photos. RAW is the original image data obtained
from the CMOS/CCD through ADC, so it usually contains some extra
information than the compressed Jpeg.
"dcraw" is an open-source software to transform the RAW photos to
"common-type" image files, e.g. "TIFF". You may download the complete
source code here:
The command to compile it is also very simple:
gcc -o dcraw -O4 dcraw.c -lm -DNODEPS
This may take some time and generate some warnings. I have successfully
compiled it and even tried it with one of my photos. The speed is not quite
impressive though. When I use: "dcraw -v +M -w -o 1 -q 3 -T IMGP0096.DNG" to
export one RAW photo from 16MP Pentax K-50, it took about 100 seconds, more
than ten times slower than my computer, as expected.