HDRMerge status update


HDRMerge is a program by Javier Celaya which takes in bracketed raw photos and spits out an HDR raw photo in DNG format. That is super awesome, for reasons!

The project’s official repository received no updates in the past year, but there were numerous speedups and bug fixes and a new feature (custom white level) made by @heckflosse, perhaps something by me, and possibly commits in forks by other users. In order to get things back on track, I reached out and Javier gave @heckflosse and myself repository access. And so it was that there came about a big merge today, and we smiled, for it was good.

This means two things:

  1. The project is alive. New patches will get merged. There are plenty of talented coders here - it would be great if you helped! Just take a look at the few issues or maybe even implement new functionality.
  2. We should release a new version of HDRMerge soon for distros to pick up so that end users can benefit. I’ll wait a while and see the response this gets before deciding on a release date.

Awesome! This isn’t packaged for a lot of distros. It is on my list of things to try and package for NixOS (though I’m not a coder by and stretch of the imagination)… Also on that to do list is a rawtherapee update, as they’re packaged version is 4.0.10 or something like that.

This is fantastic news, and super-exciting to hear that you both are picking things up! Thank you!

1 Like

Glad to hear that the HDRMerge project isn’t abandoned! I’ve used it a few times, it can do wonders!

That is good news!

I’ve been using the Google Nik collection for HDR, and while free, is not open source.


Wonderful! Thanks for picking it up! I have a great many of new bracketed shots from my holydays to be processed with HDRMerge, so your timing is just perfect.


I’ve tried HDRMerge for the first time (0.5.0, in both Ubuntu and Windows), and Darktable (2.0.5, Ubuntu) doesn’t seem able to import a resultant DNG file:

failed to read camera white balance information from (filename)

RawTherapee does seem to be able to use it without issue.

Is this an HDRMerge or a Darktable issue?

@DavidOliver At least one of the formats spit out by hdrmerge (16, 24 or 32 bit floating point) is not supported by dt. I don’t know which one it is. But if you try all of them you should get a dng which can be imported by dt.


Thanks, @heckflosse. Unfortunately, I’ve now tried all three bit-depths and the problem exists for all of them.

Then you have to ask in dt forum :frowning:


Floating-point DNGs are unsupported by libraw and programs which use libraw.
I opened a request at libraw’s issue tracker for adding support for it in 2014, but the request was closed.

If you want support for it added to libraw (and thus enabling support of it to every program which relies on libraw), click the link above and voice your support.

Ah, I see - thanks. I should have caught on as it’s covered in HDRMerge’s readme. So my workaround would be to save as a 16-bit integer TIFF using RawTherapee, either before or after tonemapping, for use in Darktable.

I’ll add a “me too” to that libraw issue, but it doesn’t sound like it’s something that’s going to be done anytime soon. I see there’s also a request to add an option to HDRMerge for integer output.

I was excited that someone requested integer output… Until I realized that it was me.

1 Like

darktable doesn’t use libraw, so fixing that wouldn’t change anything. Last I checked the problem with HDRMerge DNGs was that they are zip compressed which rawspeed doesn’t support. See if you can turn that off.

Currently HDRMerge is hard coded to write compressed DNGs

@patdavid How about adding a new HDRMerge category in ‘Software’?

Morgan_Hardwood currently tries to crosscompile a new HDRMerge Windows build on Linux (any help is appreciated) and there are also thoughts how to continue (improve) HDRMerge project. Currently the only active contributors are Morgan and me. We welcome new contributors. The code base of HDRMerge is small and clear and if there are questions about the code I’ll give my best to help.



Will do! I’ll get it set up tonight after I get the kiddos to bed.

1 Like

I also think this is probably worry a blog post at least to raise some awareness. I’ll start on something later this week and try to get it mentioned in some other places as well.


Thanks, Pat! I’ve a lot of ideas how to improve HDRMerge like using a different decode engine than libraw; raw preprocessing as in RT (badpixels interpolation and raw ca-correction before merge and so on…)

1 Like

I think that some automatic distortion correction (maybe with lensfun) could help with the alignment of handheld shots.

Also, is there a CLI version without QT dipendencies?

I could help with an appimage, of course :wink: