Parameters dependent on the image content

I am trying to stitch two images taken with different cameras, and for this I want to use RAW. But dcraw_process() and dcraw_make_mem_image() perform some image enhancement operations. Some of the enhancements are dependent on the content of the image, for example the use the histogram of the image to determine the specific enhancement. I try to look in to the documentation but I couldn't differentiate which uses camera information, image information, specific algorithm and so on. How could i categorize the operation based on the above classification.


You may set

You may set imgdata.params.no_auto_bright to non-zero to avoid auto-brightening.

-- Alex Tutubalin

imgdata.params.no_auto_bright to non-zero is not helping

The images taken are a series of photos even if i avoid the auto parameters i still find a significant difference in the radiometry so i am thinking there are some parameters that use the content of the image. As you know in this case the nature of the image is considered which gives me very different images radio-metrically. To avoid this i need to understand which uses the image content to perform enhancement which doesn't. Could you provide me something on this please.

Getu Nigussie

To completely turn off any

To completely turn off any 'automation', you need to
- use same white balance coefficients (set params.user_mul to same values to make sure)
- use same black level (params.user_black)
- use same saturation level (params.user_sat) or do not use automated saturation calculation
(params.adjust_maximum_thr = 0)
- do not use auto_brigtening (as described above)

-- Alex Tutubalin

Accessing the computed parameter values

Alex thanks for your support,

Turning of the the automation is giving me very bad images compared to the automated once. So, I would like to work with the automation but use the first images parameters for the rest of the set. Is there any way that i could retrieve the computed parameters(not the flags) by libraw and use them for the next RAW image? I don't want the parameters to be computed again and again for each raw file!!


Getu Nigussie

White balance and black level

White balance and black level data can be retrieved after open_file (cam_mul, black and cblack[]).

Unfortunately, auto-brightening uses local variables, you need to modify copy_mem_image() code to save parameters somewhere if you use dcraw_make_mem_image() call.

-- Alex Tutubalin