HDR heatmaps and torch mode UHDs

[StingingVelvet]

Originally Posted by Fendergopher

Are grading tools for HDR not sophisticated enough so that you can blow out detail in particular highlights without also pushing thousands of nits through it at the same time? Or am I misunderstanding what he's saying there.

That's how it reads to me too, which is odd.

[dorian]

HDR Heatmap Colab Notebook

1. Install dependencies
   
   
   
   Click the play button within the green square I outlined to install the dependencies required to run the script.
   
   
   
   A green tick on the left hand side indicates the dependencies have been installed and you can proceed to the next step.
   
   
2. Load 3D LUT & Colour bar
   
   
   
   Click the play button again to load the lookup table and the colour bar overlay.
   
   
   
   Once you see the green tick you can move on to the next step.
   
   
3. Upload images
   
   
   
   Click the play button to create the upload option.
   
   
   
   Click the choose files button and select 1 or multiple screenshots you'd like to process. Make sure the screenshots are 16-bit PNG images encoded with the ST 2084 EOTF and have not been tone mapped.
   
   
   
   Once your image/s have been uploaded you can proceed to run the script.
   
   
4. Run script
   
   
   
   Make sure the aspect ratio of the content in the screenshot is correctly set to ensure accurate average light level values. You can click on the script and edit the aspect ratio. Click the play button to finally run the script.
   
   
   
   The heatmap will automatically start downloading after the script has run. Your browser may request permission to download multiple files.

I have tested the notebook and it should run fine but let me know if you have any issues.

[Macatouille]

Originally Posted by dorian

HDR Heatmap Colab Notebook

Thanks so much for setting this up. What app/program do you like to use to take 16-bit PNG screenshots?

[chip75]

Originally Posted by Fendergopher

Are grading tools for HDR not sophisticated enough so that you can blow out detail in particular highlights without also pushing thousands of nits through it at the same time? Or am I misunderstanding what he's saying there.

Originally Posted by StingingVelvet

That's how it reads to me too, which is odd.

I think you'd get a pretty dull low contrast image that way. He wanted to lose the detail in the explosion, but give it a high peak brightness. The Annabelle stuff is interesting as it's something that could be overlooked, but it needed to be attention.

Thankfully they seem invested in the process of HDR mastering as much as other stages of production, so that's commendable.

[dorian]

Originally Posted by Macatouille

Thanks so much for setting this up. What app/program do you like to use to take 16-bit PNG screenshots?

I use ffmpeg directly through CLI. 16-bit isn't strictly necessary but recommended for the sake of precision. I haven't tried too many players but I know VLC takes 8-bit PNG screenshots that should work.

[Macatouille]

Originally Posted by dorian

I use ffmpeg directly through CLI. 16-bit isn't strictly necessary but recommended for the sake of precision. I haven't tried too many players but I know VLC takes 8-bit PNG screenshots that should work.

As a test I ran this command on my own rip of Die Hard to get a screenshot in ffmpeg:

ffmpeg -i "C:\location\DieHard.mkv" -ss 00:00:10.000 -frames:v 1 C:\location\Check1.png

That produced this (which I've sized down to upload):



And then I used that screenshot in your workbook, adjusting the aspect ratio from 2.4 to 2.39, and it gave me this:



Did I do that right?

[gkolb]

Originally Posted by bluebeards

Does the script only work on base HDR layers? No FEL, RPU, or HDR10+ considerations?

RE: HDR10+, the metadata for this format resides inside the HDR10 file. It’s not in a separate file like a DoVi MEL or FEL metadata/enhancement file (for disc releases). I’m just clarifying where the data resides. If there’s a program or process that can apply the 10+ metadata, then you should be able to capture the combined end product as a png file. Hope this helps.

Although HDR10+ seems to be a dying format for disc releases. For streaming, some remarks that I’ve noticed say it’s still being used, but I’ve no idea what releases are using it.

[AxeYou]

Originally Posted by gkolb

RE: HDR10+, the metadata for this format resides inside the HDR10 file. It’s not in a separate file like a DoVi MEL or FEL metadata/enhancement file (for disc releases). I’m just clarifying where the data resides. If there’s a program or process that can apply the 10+ metadata, then you should be able to capture the combined end product as a png file. Hope this helps.

HDR10+ is just metadata anyway. It doesn’t materially change the HDR10 grading. So there shouldn’t be anything extra to capture in the context of a (raw, i.e. non-tonemapped) HDR screenshot. Same goes for DV MEL. Only FEL requires combining the HDR10 BL with additional data for accurate measurement.

[AxeYou]

Originally Posted by dorian

HDR Heatmap Colab Notebook

1. Install dependencies
   
   
   
   Click the play button within the green square I outlined to install the dependencies required to run the script.
   
   
   
   A green tick on the left hand side indicates the dependencies have been installed and you can proceed to the next step.
   
   
2. Load 3D LUT & Colour bar
   
   
   
   Click the play button again to load the lookup table and the colour bar overlay.
   
   
   
   Once you see the green tick you can move on to the next step.
   
   
3. Upload images
   
   
   
   Click the play button to create the upload option.
   
   
   
   Click the choose files button and select 1 or multiple screenshots you'd like to process. Make sure the screenshots are 16-bit PNG images encoded with the ST 2084 EOTF and have not been tone mapped.
   
   
   
   Once your image/s have been uploaded you can proceed to run the script.
   
   
4. Run script
   
   
   
   Make sure the aspect ratio of the content in the screenshot is correctly set to ensure accurate average light level values. You can click on the script and edit the aspect ratio. Click the play button to finally run the script.
   
   
   
   The heatmap will automatically start downloading after the script has run. Your browser may request permission to download multiple files.

I have tested the notebook and it should run fine but let me know if you have any issues.

Thanks, dorian! Very neat.

Two minor nitpicks re. aspect_ratio:

• It looks like the code as written only (sort of) works when the black bars are at the top or bottom. Plenty of catalog titles have black bars on left and right.
• The actual active image area may not always be aligned at the dead center of the frame. IIRC David M has mentioned he occasionally would shift the image a couple pixels up or down to align with quantization boundaries (I forgot if this is the right term), in order to maximize encoding efficiency. So for example the black bar can be taller on the top than on the bottom.

Perhaps 4 separate variables, top, bottom, left, right padding, would work best.

[dorian]

Originally Posted by AxeYou

Thanks, dorian! Very neat.

Two minor nitpicks re. aspect_ratio:

• It looks like the code as written only (sort of) works when the black bars are at the top or bottom. Plenty of catalog titles have black bars on left and right.
• The actual active image area may not always be aligned at the dead center of the frame. IIRC David M has mentioned he occasionally would shift the image a couple pixels up or down to align with quantization boundaries (I forgot if this is the right term), in order to maximize encoding efficiency. So for example the black bar can be taller on the top than on the bottom.

Perhaps 4 separate variables, top, bottom, left, right padding, would work best.

I totally forgot about narrower aspect ratios lol. The code should be fixed now. Thanks for the heads up! I don't think shifting the mask a few pixels either way will have much, if any, impact on the average light level values but I may incorporate it later on. I also added a decimal place in the output values for greater precision.

[Macatouille]

Well, here goes nothing:


Hocus Pocus (1993)

Mastering display luminance              : min: 0.0001 cd/m2, max: 1000 cd/m2

Heatmaps

[Show spoiler]

Gamut Visualizations

[Show spoiler]

HDR10 Plot

[Macatouille]

Alien (1979)

Mastering display luminance              : min: 0.0050 cd/m2, max: 1000 cd/m2

Heatmaps

[Show spoiler]

Gamut Visualizations

[Show spoiler]

HDR10 Plot

[Geoff D]

Originally Posted by Fendergopher

Are grading tools for HDR not sophisticated enough so that you can blow out detail in particular highlights without also pushing thousands of nits through it at the same time? Or am I misunderstanding what he's saying there.

Originally Posted by StingingVelvet

That's how it reads to me too, which is odd.

Not sure what the confusion here is. The colourist wanted a specific 'blown out' look to the explosion similar to how one looked in Akira. But HDR as a system automatically exposes a lot of latent highlight information if it's present in the signal, which even applies to VFX deliverables as they usually get done in a log space that's similar to the original ungraded capture. When matey brought that explosion into the HDR space it unveiled a lot of info that he didn't want to be seen but he still wanted it to be good and bright, so he had to use the grading tools to thicken the highlights and blow them out whilst retaining the brightness.

[Fendergopher]

Originally Posted by Geoff D

Not sure what the confusion here is. The colourist wanted a specific 'blown out' look to the explosion similar to how one looked in Akira. But HDR as a system automatically exposes a lot of latent highlight information if it's present in the signal, which even applies to VFX deliverables as they usually get done in a log space that's similar to the original ungraded capture. When matey brought that explosion into the HDR space it unveiled a lot of info that he didn't want to be seen but he still wanted it to be good and bright, so he had to use the grading tools to thicken the highlights and blow them out whilst retaining the brightness.

It was mostly just his wording that confused me late that night. I should've just remembered the "SDR in an HDR container" gradings we have and that would answer my question right there, lol.

[PeterTHX]

FFS, do we need the same wall of text posted over & over?

[Macatouille]

12 Monkeys (1995)

Mastering display luminance              : min: 0.0001 cd/m2, max: 1000 cd/m2

Heatmaps

[Show spoiler]

Gamut Visualizations

[Show spoiler]

HDR10 Plot

[Fjodor2000]

Originally Posted by Macatouille

12 Monkeys (1995)

[Show spoiler]

Next up: Ad Astra, Akira, Almost Famous, Apocalypse Now (Final Cut).

I can slow down if this is adding too much load on the thread.

Thanks!

Any chance you could also include these wildly disputed screenshots in the analysis? :

https://forum.blu-ray.com/showpost.p...&postcount=960

There was a long discussion in that thread regarding whether the highlights were sufficiently "blown out" in the "flashback" scenes. See timestamps in the post linked to above.

[dorian]

Originally Posted by Fjodor2000

Thanks!

Any chance you could also include these wildly disputed screenshots in the analysis? :

https://forum.blu-ray.com/showpost.p...&postcount=960

There was a long discussion in that thread regarding whether the highlights were sufficiently "blown out" in the "flashback" scenes. See timestamps in the post linked to above.

[Show spoiler]

[Macatouille]

Originally Posted by Fjodor2000

Any chance you could also include these wildly disputed screenshots in the analysis? :

https://forum.blu-ray.com/showpost.p...&postcount=960

There was a long discussion in that thread regarding whether the highlights were sufficiently "blown out" in the "flashback" scenes. See timestamps in the post linked to above.

Glad to see dorian's output matches mine:

[Show spoiler]
Flashback:









Finale:

Pretty clear difference in values between the two scenes.

[Fjodor2000]

Originally Posted by dorian

[Show spoiler]

Originally Posted by Macatouille

Glad to see dorian's output matches mine:

[Show spoiler]
Flashback:









Finale:

Pretty clear difference in values between the two scenes.

Just so I understand what you are comparing in those two analyzed screenshots: I assume both are from the 4K BD? I.e. first screenshot(s) from the blown out "flashback" scene, and then the non-blown out one(s) from the Finale?

Because just to clarify, I think nobody disputed that there was a difference between those. The dispute was whether the blown out scenes on the 4K BD were sufficiently blown out. More specifically, if the blown out scenes were even more blown out on the BD.

To determine that, I guess a similar analysis would have to be made of the same screenshots when taken from the BD instead, so the screenshots from the BD vs 4K BD can be compared. But I don't know if the analysis tools that you are using also are able to handle SDR screenshots from BD, or only HDR screenshots from 4K BD?