LibRaw technical support

Stable LibRaw versions: technical support, errors, API questions

LibRaw image size data vs Adobe interpretation

Submitted by Fimagena on

Hi,

I have been doing some comparison of the size data (i.e., libraw_image_sizes_t struct) that LibRaw reads vs how Adobe interprets raw images (by using the DNG converter and reading the tags - same data as in Lightroom/Photoshop). Reason is that I'm working on a DNG-converter using LibRaw and would like the results to be as close to Adobe's version as possible (rightly or wrongly).

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LibRaw 1.7beta1 vs dcraw 9.26 result

Submitted by xDreamer on

Hi,
I was trying to get the similar output to dcraw 9.26-x64 from LibRaw 1.7beta1-x64, but had no luck. Is it possible to get the exact 1:1 match to dcraw? It seems LibRaw is performing some sort of auto adjustment beyond "no_auto_bright", I tried "no_auto_scale" from my code too but it didn't help.

dcraw command:
"dcraw.exe" -v -w +M -n 10 -H 0 -o 1 -W -g 1.0 1.0 -q 3 -6 -4 -T "image.cr2"

dcraw_emu command:
"dcraw_emu.exe" -v -w +M -n 10 -H 0 -o 1 -W -g 1.0 1.0 -q 3 -6 -4 -T "image.cr2"

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optimisation/bug in convert_to_rgb() ?

Submitted by KevinJW on

I'm wondering if the code in dcraw_common in convert_to_rgb() is wrong...

#ifndef LIBRAW_LIBRARY_BUILD
raw_color |= colors == 1 || document_mode ||
output_color < 1 || output_color > 5;
#else
...

I thought it should be setting libraw_internal_data.internal_output_params.raw_color so that the convert_to_rgb_loop() function would not apply the matrix?

Also I wondered about adding an option to not compute the histogram in that function?

Thanks

Kevin

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Modify parameters of raw image

Submitted by hust_mark on

How can I modify parameters like "ISO speed","shutter ","timestamp".
For example : firstly, open a Raw file "test.CR2", then define LibRaw RawProcessor; i want to modify "shutter"of "test.CR2",my opinion is : RawProcessor.imagedata.other.shutter=8.9. But it does not work, the "test.CR2" file is not changed. how can i modify some parameters of RAW images.

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Difference dcraw and dcraw_emu in sequential brightness.

Submitted by TimZ on

Case: i have two exactly the same images, shot with 5 seconds in between.
These two images are visually identical when viewed:
In their JPEG preview.
In Adobe ACR
In dcraw (tested v9.22, 9.24 and 9.25) with commands -T -w -W.

Then when i use dcraw_emu as:
dcraw_emu -T -w -W

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Relations between cam_xyz and rgb_cam

Submitted by Jay L on

Hi,

First of all, thanks for library. I have to say LibRaw is amazing.

I was confused when I tried to transform color space between camera color space, sRGB, and CIE XYZ.

I have read the documents from https://github.com/LibRaw/LibRaw/blob/master/doc/API-datastruct.html
It seems cam_xyz converts from camera color space to CIE XYZ, and rgb_cam converts from camera color space to sRGB.

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MetaData

Submitted by mvms2015 on

Using exiftool on a .CR2 photo converted to DNG, the following tags can be seen in the printout.

AS_SHOT_NEUTRAL
Raw Data Unique ID

However, when unpacking an image captured from the same camera (Canon 7D), I cannot find that data in the libRaw.imgdata structure, despite reading through the sub-structure data several times when in debug mode. I have found almost everything else needed.

I also scanned the documentation.

Any help wold be welcomed.

Thanks. Great library.

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