Inspired by discussion triggered by my PREVIOUS POST on this topic, and after watching an interview with Alister Chapman, I experimented with HLG footage a bit more (without a special HDR Monitor). This time, rather than converting HLG clips to Rec.709 clips, I created a new video in true HLG format, to see how it would work for both HDR and SDR TVs.
I actually ended up creating two versions of the same video. Both versions were created with the same Video Codec:
‘HDR TV’ version – in this version I wanted to see what would be the quality of the video without any color grading (okay, almost no color grading)
‘SDR TV’ version – in this version I did some minimal color grading to get an image quality on an SDR screen similar to the one an HDR screen (in my subjective opinion).
I selected several video clips that I shot in HLG (BT2020 color space) at different depths (from 5 m to 35 m) and did the following (mostly following Apple’s recommendations):
1. Created a library in FCPX and set it to Wide Gamut HDR
2. Imported all clips to this library
3. Slightly adjusted Midtones by lowering brightness to -0.1 (this what I understand Alister Chapman has recommended)
4. Slightly adjusted Hue vs Hue of Hue/Saturation Curve of a few clips to change water color from greenish to blueish.
5. Slightly increased sharpness (3.78)
6. Applied HDR Tool (PQ Output Tone Map)
7. Shared the project as a Master File, using Video Codec: Apple ProRes 422 and Wide Gamut HDR - Rec. 2020 HLG color space
8. Uploaded the Master file to YouTube
As you can see from the above steps, I basically did not do any color grading, and all above steps took me only about 5 to 10 min, as I was using adjustment layers, to which I applied most adjustments, rather than to individual clips.
Here is the LINK to the 'HDR TV' version of the video.
When I watched this video on the my HDR TV (Samsung Q80R, 2019) I was quite impressed with its quality.
Then, I watched the same video on my old plasma TV and a 2-year old HDR TV, on iMac, on MacBook Pro (2018), on iPhone X, and on my new Dell laptop (2020). I noticed that colors on these screens got 'washed out' a bit, compared to colors on my HDR TV. So, I decided to create another version of this video (‘SDR TV’ version), in which, in addition to the above steps 1 to 8, I made the following adjustments to increase contrast and brightness:
1. Increased brightness of Highlights up to +0.21
2. Decreased brightness of Shadows down to -0.22 for some clips
3. Increased saturation of Midtones slightly
As a result, I got a video with quality quite comparable to the ‘HDR TV’ version (in my humble opinion). As such, it appears that for people who do not watch YouTube videos on an HDR TVs the second version ('SDR TV') would work better.
Here is the LINK to the 'SDR TV' version of the video.
Most probably, quality of this second video could be improved further by making some additional adjustments, but I already see that shooting in HLG underwater could produce very good quality videos (at least to my taste) without much grading and without a special HDR monitor.
I should note, however, that I am not sure how good could be quality of underwater footage shot in HLG picture profile using other cameras. With SONY cameras like the one I have (Sony FDR-AX700 / HXR-NX80 / PXW-Z90), it is very easy to set manual white balance underwater with just one click, and I did it for every single shot. Sometimes, however, when there is not much ‘white’ color in a scene to be used by the camera for reference, you have to experiment a bit, and this is where the mastery is. I am not there yet, and I need to practice more to improve this skill.
Also, I would like to mention that I am not an expert in HLG, and if anyone is interested in learning more about advantages of HLG I would refer to experts like Alister Chapman.
If you would like to learn more about using HLG in underwater videography, I would refer you to J. M. Núñez’s WEBSITE. Juan has tonnes of experience in shooting HLG underwater, and his website is full of very useful and practical information and tips.
Please share your opinion about picture quality of the two versions of my video on HDR and SDR screens when you have time.
Thank you all. Stay home and stay healthy.