LibRaw technical support

Stable LibRaw versions: technical support, errors, API questions

using example, image data not understood

Submitted by fyngyrz on

Reading a CR2 canon file from a Canon 6D MK1, known good. Using the example code on the "https://www.libraw.org/docs/API-overview.html" page; the max value out of any RGBG sample is about 5600. Scaling the data up ((data/5600.0)*65535) to a full 16bit sample results in what looks like fairly even tempered noise, not anything like the image data that is actually in the file.

I want to read out the RGB values of the image, and this doesn't seem to do that:

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Using LibRaw.sln to build to support FujiFilm GFX 50S

Submitted by johnbuuck on

I am using LibRaw.sln to build LibRaw but can't figure out what I need to change in order to support the new FujiFilm GFX 50S camera. I tried adding the Preprocessor define LIBRAW_OPENMP but that did not work - I get " Cannot unpack C:\CameraFilesTests\IN\Canon\MM8717_170913_08471.RAF: Input/output error"

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Compiling with emscripten

Submitted by joshcomley on

Hi there,

I am trying to compile LibRaw with emscripten for use with a web project, but struggling, and am unable to find any existing resources online.

I have successfully compiled LibRaw in Visual Studio, but emscripten requires a CMake file, which my knowledge of is limited, and Visual Studio support for emscripten ended with VS2010.

I have also set up emscripten correctly and compiled "hello world" etc., but I do not know how to organise the code so as to compile(/transpile) with emscripten.

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cam_xyz ColorMatrix2 mismatch

Submitted by james on

I've been trying to debug some issues that I've been experiencing on Canon 6D files, and started comparing the matrices shown by raw-identify on the original .cr2 and that same file converted to .dng. Based on this post, my understanding was that cam_xyz should exactly match ColorMatrix2. However, here is what I see for one such raw file (the numbers are the same for all the files I've tested):

Original CR2:

Camera2RGB matrix:
1.7944 -0.5655 -0.2289
-0.2979 1.5021 -0.2042
0.0735 -0.6031 1.5296

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Nikon NEF RAW data minimum value clamp

Submitted by Peter W on

When I use DCRAW to extract the RAW pixel values from a NEF file made by my D5300 I notice that there seems to be a minimum value clamp = 588 applied to the pixel values. I am an astrophotographer so generating master BIAS and DARK frames is part of my image calibration method. Both BIAS and DARK frames are images with the lens cap in place so that no light enters the camera. I believe that Nikon uses a Darkness value of 600 in their NEF files. The 588 minimum value clamp causes a huge number of pixel values in my individual DARK frames to be clamped at 588.

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use_camera_wb

Submitted by JacksBack on

Hello,

I can't seem to get the libraw_data_t->params.use_camera_wb flag to work. I suspect I'm doing something wrong.

I have a Sony .ARW file which unpacks with the wrong colors if use_camera_wb isn't set to 1. It unpacks correctly under dcraw with use_camera_wb set to 1.

Setting this item to 1 in libraw causes it to unpack with the wrong colors.

Here's a simplified version of what I'm doing - I'm using the libraw C interface.

libraw_data_t *lrd=libraw_init(0);

lrd->params.use_camera_wb=1;

libraw_open_file(lrd,path)

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