Blackmagic Forum

I'm not sure if this is bug or (significant) limitation.

Currently Cinema DNG IDT doesn't seem to work correctly because only 3x3 matrix transform is applied when converting from camera colour space to CIE XYZ and ProfileHueSatMapData LUT is ignored. This leads to significant colour inaccuracies.

In order to comply with Cinema DNG Specification, the IDT must also apply ProfileHueSatMapData LUT.

An interesting point..
I'm not an image/color engineer but I was having a possible related discussion today with someone using cDNG from DJI. I noticed that none of the non-native colorspace/gamma options yielded the same results after conversion with a resulting image looking more red-ish. Could this be related?

viewtopic.php?f=21&t=159835

I tested converting from DLog/DGamut to Rec.709/Gamma 2.4 via CST and with the same source switch to Rec.709/Linear on the raw tab and convert from there back to D-Log gamma with DJI LUT. Then convert to Gamma 2.4 with CST and leave the colorspace. Both using DaVinci default tonemapper.
With this assuming the way Resolve internally converts / uses DNG in colormanaged setups is incorrect? Because using the CST only is of course outside of the cDNG processing if DLog/DGamut is it's 'unaltered' state.
Correct me if I'm wrong.

I don't think it is the same issue.

Unlike other raw formats, cDNG is unique in that it also contains an IDT to transform from camera colour space to CIE XYZ. This IDT consists of several matrices and optional LUT. This LUT is unique in a way that it helps map saturated colours more accurately than a linear 3x3 matrix can.

Lightroom, photoshop, and FAST DNG Processor, do take the optional LUT into computation, resulting in more accurate saturated colours and prevent gamut clipping to some extent.

It appears Davinci Resolve throws away the LUT part of the IDT, making it inconsistent with results obtained using full IDT processing pipeline as set out in DNG Specification.

I've also noticed that Resolve is ignoring Profile Hue Sat Maps as well. Resolve certainly honors both Color Matrices for Standard A and D60/D65 which is helpful, but I wonder if there could be an option in the Camera RAW Cinema DNG project settings to either honor or dishonor Color Matrices and/or Input IDT (Profile Hue Sat Maps).

Having a similar issue with cDNG footage from Sigma FP where embedded Color Matrices are different when the camera was shooting with internal color modes switched on or off.

Devon, Pawel, do either of you know of a software or command line tool that debayers the cDNG to D-Gamut/D-Log as you believe DJI intended?

I recently commented to this Logik forum thread: https://forum.logik.tv/t/dji-inspire-3-footage/8919/1

I'd be very curious to find some sense of ground truth in all this!