Postprocessing like raw viewers

Hi there,

Thank you for all the hard work that you're putting into the development and support of LibRaw. We're already successfully using LibRaw in our project for extracting metadata.

We're currently trying to decode raw files in order to show it to end-users. At the moment, we're just setting the following output parameters:

gamm[0] = 1.0 / 2.4;  // sRGB gamma
gamm[1] = 12.92;
use_camera_wb = 1;

The colors seem a bit washed out for most images we've tried when comparing this to the rendering of raw viewers (like FastRawViewer, LightRoom, Mac OS Preview, etc).

Which other parameters should we set or what postprocessing should we do to make it roughly similar?

Thank you!

Stijn Seghers (Narrative)


LibRaw::dcraw_process output

LibRaw::dcraw_process output is close (enough) to FastRawViewer in fixed contrast + auto ETTR mode.

-- Alex Tutubalin @LibRaw LLC

Thanks for the quick reply,

Thanks for the quick reply, Alex.

The fixed vs variable contrast indeed seems to be the major contributing factor to the difference. I'm not familiar with that terminology; could you explain what variable contrast mode does? Can LibRaw emulate it?

dcraw.c's postprocessing

dcraw.c's postprocessing (LibRaw::dcraw_process is derived from it) do not have contrast controls.

-- Alex Tutubalin @LibRaw LLC


Thanks for your help, Alex. We'll try to figure out how to apply such a variable contrast transformation ourselves then.