ACEScg with merging bracketed photos

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Jez Hardin

Mar 7, 2018, 11:21:00 AM3/7/18

Apologies if this has been covered elsewhere.

Is there an ideal way to take bracketed CR2s into a single HDR and into Aces CG?

Most of the off the shelf tools I've seen are merging without exposing or considering colourspace.

(I was using OCIO convert on the individual CR2 files to take them to exr, but that seemed to lose range with the configs I was using, and that was before getting into bracket merging.)

Any advice is welcome.


Feb 19, 2019, 3:45:32 PM2/19/19
to OpenColorIO Users
I am currently developing a RAW image editor that has recently gained support for OCIO configs and ACES-based workflows.

The RAW editor is called PhotoFlow and can be grabbed here:

The workflow I'd suggest in this case is the following:
* load the CR2 files in HDRMerge (, and save the output as a floating-point DNG. HDRMerge takes care of merging the bracketed shots into a single RAW file that covers the full dynamic range of the bracketed sequence. The well-exposed portions of each shot are used in the merging. Note that this is not a tone mapping or exposure fusion tool, so the output is still a linear RAW file with pixel values proportional to the scene illumination
* open the floating-point DNG in PhotoFlow, and export the result as a demosaiced 32-bits floating-point TIFF in ACEScg colorspace

This is a quite over-simplified description, but I'd be happy to provide you many more details if you are interested.

Hope this will help you!

Francois Lord

Feb 21, 2019, 9:55:28 AM2/21/19
Ah! An application that can load float DNGs and use OCIO? I'm going to have to take a closer look then!
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PhotoFlow Editor

Feb 21, 2019, 12:33:30 PM2/21/19
to OpenColorIO Users

On Thursday, February 21, 2019 at 3:55:28 PM UTC+1, Francois Lord wrote:
Ah! An application that can load float DNGs and use OCIO? I'm going to have to take a closer look then!

You are welcome! From my side, I need people that can describe me their needs and can help improving the workflow.

Would you have a typical usage example? Which kind of OCIO config would you need for the processing?
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