skyscope
Core User of DJI
Flight distance : 4514797 ft
Germany
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GregL2570 Posted at 5-27 09:59
Only the HLG file contains a truly wide dynamic range input color space (BT.2020 HLG). Both the D-Log and D-Log M files contain HD (1-1-1) input color spaces, which, despite the appearance of a flat, low contrast, log gamma profile, are actually both recognized as Rec709 input color spaces.
You shouldn't focus too much on the clip-metadata, the infomation is in the streams. When it comes to color space, DLog's is much larger than HLG's (D-Gamut vs. Rec.2100/2020). Also, regarding the gamma curve, DLog offers significantly more dynamic range.
DLog is the common denominator with the Mavic 3, for example, you can easily create HLG (or PQ, HDR10, DolbyVision) from DLog, but not the other way around. Besides, HLG isn't really suited for post-production work because it has a linear gamma up to about 60%, and only above that does it have a logarithmic transfer (hence the name Hybrid Log Gamma).
This makes it very hard, if not impossible, to grade consistently across different shots with different exposure. HLG is really a delivery format, and you should only use it for recording if you plan to play it back exactly as it is in a HDR Pipeline. In a SDR Pipeline you wil get in a lot of trouble with grading HLG.
In the end, as I said, it contains less information than DLog, both in terms of color space and dynamic range. Take a look in the DLog/D-Gamut Whitepaper from DJI, but you can check this all out for yourself using the right HDR color workflow and settings and for example the CIE plot in DaVinci Resolve.
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DLog / D-Gamut
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