Recent comments

Reply to: iPhone 11 Halide DNG gives black image.   2 years 7 months ago

Thank you. I looked in to this more, it turns out the libraw->rawdata.color.cam_xyz field is blank with DNG images. I had to look at libraw->rawdata.color.dng_color

Sorry about the mistaken post!

I have a suggestion: Maybe put DNG's ColorMatrix2 (Daylight) in to the cam_xyz field? It might reduce confusion for some developers.

I am using build from latest source code from github.

Reply to: How to compute White Balance from cam_mul?   2 years 7 months ago

In colour science CCT is derived from xy. xy calculation depends on the colour transform, raw to XYZ. This transform is not one-to-one because raw data isn't colorimetric. Different companies use different colour transforms for the same camera model. Say, the camera and ACR report different CTs for the same shot.
Your best bet is to shoot a camera at each CT setting, compile a table of CTs vs. wb coeffs, and interpolate.

Reply to: How to compute White Balance from cam_mul?   2 years 7 months ago

What I want to do is to give user a Color temperature slider that needs to start with the color temp of the photo (say 5000K) and let him move in the range of say 2000-10000K.

So how do I compute this using the various data obtained in libraw_colordata_t? I thought cam_mul is a start?

Reply to: How to compute White Balance from cam_mul?   2 years 7 months ago

White balance is not measured in Kelvins.

Reply to: How to enable multiple processors support for macOS?   2 years 7 months ago

There is no omp.h file in standard toolchain

Reply to: How to enable multiple processors support for macOS?   2 years 7 months ago

This is no longer true. Standard Apple Toolchain works with OpenMP. Just add -Xclang -fopenmp to the compile flags.

I have to add -DLIBRAW_FORCE_OPENMP in the Makefile.dist in order for it work for standard Apple Toolchain.

That aside, but how do I control the number of threads to use? It seems be always the same as the number of logical processors.

Reply to: How to enable multiple processors support for macOS?   2 years 7 months ago

Probably we need to remove comment 'need to recheck': rechecked and, yes, it will not work in standard Apple-provided environment

Reply to: How to enable multiple processors support for macOS?   2 years 7 months ago

If you're speaking about:
#elif (defined(__APPLE__) || defined(__MACOSX__)) && defined(_REENTRANT)
/* Latest XCode works with OpenMP, need to recheck here */
#undef LIBRAW_USE_OPENMP

This is not bug, but specially added because standard Apple toolchain does not support OpenMP

For other toolchains one may use -DLIBRAW_FORCE_OPENMP to enable this #if-branch:
#if defined(LIBRAW_FORCE_OPENMP)
...

Reply to: How to enable multiple processors support for macOS?   2 years 7 months ago

Just follow the instructions on this link:

https://mac.r-project.org/openmp/

I grabbed the OpenMP dylib there and it compiles fine. No need to download another version of llvm.

In fact, I finally got LibRaw to work. There is a bug in Libraw_types.h in which it failed to detect -fopenmp when compiling via Xcode. Fixing that LibRaw compiles just fine using Xcode 12.4 with OpenMP support.

The question I have now is: how to control the number of threads during decode? It seems the #pragma parallel will cause the number of threads creation the same as the number of logical processor. I don't want that many. Is there a way I can alter that during runtime before calling unpack()?

Reply to: How to enable multiple processors support for macOS?   2 years 7 months ago

I'm unable to build openmp app with Xcode/clang because of omp.h missing. find / -name omp.h returns nothing.

So:
1) It is not possible to compile LibRaw with openmp using standard Apple tools (12.4 and 12.5)
2) If you was able to compile it: that means you have omp.h from some other build tools, we're unable to provide support in that case. You may add some #error preprocessor directives into LibRaw sources near #pragma omp to make sure it compiled with openmp or not.

Reply to: How to enable multiple processors support for macOS?   2 years 7 months ago

Xcode 12.4 actually works with -fopenmp, you need to add -Xclang option just before it.

I made a small sample code like this:

int main(int argc, const char * argv[]) {
omp_set_num_threads(8);
#pragma omp parallel
#pragma omp critical
NSLog(@"Greetings from thread %d", omp_get_thread_num());
return NSApplicationMain(argc, argv);
}

And I get this on the console:

2021-10-20 16:23:46.653740-0700 Test[14661:304853] Greetings from thread 0
2021-10-20 16:23:46.653954-0700 Test[14661:304941] Greetings from thread 1
2021-10-20 16:23:46.653985-0700 Test[14661:304943] Greetings from thread 3
2021-10-20 16:23:46.654015-0700 Test[14661:304942] Greetings from thread 2
2021-10-20 16:23:46.654045-0700 Test[14661:304944] Greetings from thread 4
2021-10-20 16:23:46.654069-0700 Test[14661:304947] Greetings from thread 7
2021-10-20 16:23:46.654085-0700 Test[14661:304946] Greetings from thread 6
2021-10-20 16:23:46.654102-0700 Test[14661:304945] Greetings from thread 5

My problem now is with libraw:

In the Makefile.dist, I uncommented CFLAGS+=-fopenmp and I added -Xclang to it, so it looks like:

CFLAGS+=-Xclang -fopenmp

It compiles fine, but when I linked my project, it'll link even I did not have libomp.dylib. So libraw is not really compiled with OpenMP support with the CFLAGS line above.

So what else is missing?

Reply to: How to enable multiple processors support for macOS?   2 years 7 months ago

Apple's clang (from XCode 12.4) refuses -fopenmp option, so OpenMP is not supported by this (standard macOS) compiler

If you use another compiler/runtime please refer your OpenMP runtime docs about "How do I control the number of CPU cores...."

Reply to: Generating ColorMatrix1 from input data   2 years 8 months ago

I'm having the same problem, Have you found any solution that you can share?

Reply to: Working with Apple iPhone ?   2 years 8 months ago

LibRaw supports iPhone's DNG files, but not HEIC files.

Reply to: iPhone 11 Halide DNG gives black image.   2 years 8 months ago

Here is TIFF-file created by dcraw_emu -w -T [your-file]: https://www.dropbox.com/s/b4st4g9o5846l6f/IMG_2407.DNG.tiff?dl=0
(tested with public snapshot/github version).

I do not see any problems here

Reply to: Fuji X-Trans files opening slow   2 years 8 months ago

dcraw_make_mem_image is the last step, applied after all postprocessing steps.

I suggest you to play with quality settings and/or half-size output. Also, OpenMP may help with default quality settings.

Reply to: Fuji X-Trans files opening slow   2 years 8 months ago

I am using "libraw_dcraw_make_mem_image". Maybe this is the issue. What should I use instat ?

Reply to: Fuji X-Trans files opening slow   2 years 8 months ago

What demosaic method for X-Trans do you use?

Reply to: Postprocessing like raw viewers   2 years 8 months ago

We ended up applying camera-specific tone curves that match the embedded thumbnail after LibRaw has finished processing it. It seems to work pretty well. We took inspiration for that from how darktable does it. (darktable is open source so you can check the code if you're interested.) I'm guessing the variable contrast mode in FastRawViewer is doing something similar.

Good luck!

Reply to: Postprocessing like raw viewers   2 years 8 months ago

Hey, I would also be interested in this topic of how to prepare a "good" visual representation of a RAW file automatically (similar to what FastRawViewer, RawTherapee, etc are doing). Using only dcraw_process() is not enough. I know in the documentation it also says that you should probably write your own algorithm. Is there any literature or open source examples of a "good enough" implementation that produces better results? Especially the exposure seems to be missing in the processing. Take a look at this example, where the top row are original RAW files as seen through FastRawViewer and the bottom row are the images created with dcraw_process(). You can hardly see the difference between the three exposures.

https://www.dropbox.com/s/jvdeu9h0bds9bse/libraw_vs_fastrawviewer.png?dl=0

Reply to: Floating-point DNG: can convert it with libraw on macos, not on linux   2 years 8 months ago

Sorry, know nothing about Debian.

There is no problem with your file and LibRaw fetched from github (current public snapshot) and compiled with -DUSE_ZLIB (and linked with -lz)

Reply to: What exactly is pre_mul in libraw_colordata_t?   2 years 8 months ago

I see. Thanks for the prompt reply!

Reply to: What exactly is pre_mul in libraw_colordata_t?   2 years 8 months ago

_rgb_cam (input data) is similar to DNG CameraMatrixN (https://www.adobe.com/content/dam/acom/en/products/photoshop/pdfs/dng_sp...) so contains both color transform and D65 WB coefficients.

Reply to: Issue while converting CR3 using draw_emu   2 years 9 months ago

What version of LibRaw do you use?

Reply to: Building, shipping libraw on macos Big Sur   2 years 10 months ago

Hi Alex,

thank you very much. I appreciated your quick reply.

Confirmed, it does the trick.

Thilo

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