LibRaw technical support

Stable LibRaw versions: technical support, errors, API questions

exp_shift doesn't work as expected

Submitted by mko on

I wanted to use the following values to shift exposure :

    imgdata.params.exp_correc = 1;
    imgdata.params.exp_shift = 1.0;
    imgdata.params.exp_preser = 0;

but only value 1.0 <= exp_shift <= 8.0 seems to result in a different exposed output ( lighter ).
All images created with setting 0.25 <= exp_shift < 1.0 look the same ( not darker ) ?

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LibRaw on Visual Studio with Target Machine x64

Submitted by imnet4all on

I can understand it is a naive question but I have searched enough and was wondering if it is at all possible to run libraw on a visual studio project with platform and target machine set to x64. Everything works fine when platform and target machine are x64, but it complains of unresolved externals whenever they 're set to x64. I wanted to integrate it into a large project which has been aimed for 64 bits so far anyway. Thank you in advance.

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Create 16bit gamma corrected image from raw image

Submitted by mko on

Hi

I'm trying to extract 16bit TIF from raw image ( gamma corrected - not linear ) and only get a very noisy / false-colored image !?
I'm certainly doing something wrong when setting up LibRaw instance...

Any hint appriciated !

Here is my pseudo code ( error handling stripped ) to extract the raw image and create a GraphicsMagick image of the created image data :

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Failing on some images

Submitted by paulexchandler on

Thanks for the effort on this! I was doing basically the same thing previously, but perhaps not as expansively.

I am having one problem that I do not understand. I am invoking the following methods:

open_buffer(data,length)
unpack()
dcraw_process()
dcraw_make_mem_image(&ret)

I am then taking the image data and with copy_mem_image trying to display it.

This is working with many, but not all raw test files that I have.

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How do I direct dcraw_emu to standard out for writing a jpeg on the fly....?

Submitted by robeastham on

When using dcraw I could set -c option to direct to stdout as specified at the top of the man page here:

https://www.cybercom.net/~dcoffin/dcraw/dcraw.1.html

This allowed me to write jpegs or pngs on the fly via the comand line (e.g. something like this: http://www.mutaku.com/wp/index.php/2011/02/cook-your-raw-photos-into-jpe...)

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Some questions to better understand the available data when opening a raw file with libraw

Submitted by irieger on

Hey folks,

last semester I did a nice seminar about image processing and somehow the demosaicing algorithms got me. So I'm now experimenting with different demosaicing and image processing algorithms and recently started to implement some testcode using libraw for reading DSLR photos. Now I have a few questions to better understand what's happening where the documentation didn't help or maybe I didn't understood it well.

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Different _mul(s)

Submitted by Sylvain on

Hi.

In my understanding, pre_mul, user_mul and cam_mul were mutually exclusive:
if use_camera_wb=1, cam_mul was being used, if use_camera_wb=0, it was pre_mul, and if pre_mul was defined, then pre_mul was being used instead of the 2 others.

However I ran the following test, showing that it is not true:

open()
no_auto_bright = 1
[...]
dcraw_process()

In [...], I try to use "as shot" white balance, setting either user_mul, pre_mul or use_camera_wb=1.
I was expecting all 3 pictures to be identical... but they're all different!

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