Plugin HDRTools for Avisynth

[Alexkral]

May I ask why the default pct_hdr_skin for PQMode in ConvertXYZ_BT2446_C_HDRtoSDR is set to 0.44? I haven't seen anything in ITU-R BT.2408 regarding this, only about HLG.

[jpsdr]

I don't remember exactly... But if indeed there is nothing in BT.2408, i probably "estimate" it using informations from several BT, and i probably choose this value because "it seems not too bad".
There is probably some curve or anything which lead me to this choice.

[Alexkral]

Ah ok, I think I know why you did it. 44% PQ equals 50 nits, same as 50% HLG. It doesn't seem too bad indeed.

[Alexkral]

I found something funny looking at your code, not that it's in the least important, but I think I should let you know. You use 2.404 as the power in the BT.1886 EOTF, but the last 4 is actually a footnote . It's not that it's important as I say, but when I found the reason it made me laugh.

Also, I'm not too sure that the inverse OETF should be used, ITU repeats all over the place something that seems to imply this opinion, but I can understand why you do it.

[jpsdr]

Thanks for the 2.404, i'll change this later. My guess is that at the time i read it, i didn't see the footnotes and thought it was misprint...

[jpsdr]

New version, see first post.

[jpsdr]

New version, see first post.

[LouieChuckyMerry]

First, many thanks jpsdr for all your effort .

I was gifted a UHD Blu-ray but don't have a 4K TV, so I figured I'd shrivel it to 1080p using AviSynth after color converting and resizing losslessly with VirtualDub2. Unfortunately, after hours of effort, I can't figure out how to tonemap BT.2020 to BT.709. I'm here because it seems to me that that's what your HDRTools plugin is for but using

ConvertYUVToXYZ(Color=1)
ConvertXYZToYUV(pColor=1)

as in your example runs fine but appears to do nothing. Please, what am I missing?

Ahhh, a video sample.

[FranceBB]

Originally Posted by LouieChuckyMerry

Unfortunately, after hours of effort, I can't figure out how to tonemap BT.2020 to BT.709.

Try this to go from BT2020 HDR PQ to BT709 with HDRTools:

ConvertBits(16)

ConvertYUVtoXYZ(Color=0, OutputMode=1, HDRMode=0, fullrange=false)

ConvertXYZ_Reinhard_HDRtoSDR(exposure_X=2.5, contrast_X=0.9)

ConvertXYZtoYUV(pColor=0)

Converttoyuv420()

If the conversion is fine but looks a bit off, change Reinhard's parameters accordingly 'till you're ok with the end result.

[LouieChuckyMerry]

Thanks for your reply, FranceBB. Your suggested script runs fine but doesn't appear to change the video in any way; i.e., the output looks the same as the input, dull and muted (the same-looking result as the script I posted above).

[Boulder]

If you have an nVidia GPU available, you can use DGHDRtoSDR to do the grading in one simple step. DGIndexNV can be used to tune the parameters per source.

[FranceBB]

Originally Posted by LouieChuckyMerry

Thanks for your reply, FranceBB. [...] the output looks dull and muted

Well, I wouldn't call it "Dull and Muted", but ok xD

Anyway, here's a comparison:




This is done with the following script:

FFVideoSource("D:\TestClip2[2160p].mkv")
SinPowerResize(848, 480)
original=last.Text("BT2020 HDR PQ 1043 nits - Original")

ConvertBits(16)
hbd=last
ConvertYUVtoXYZ(Color=0, OutputMode=1, HDRMode=0, fullrange=false)
ConvertXYZ_Reinhard_HDRtoSDR(exposure_X=2.5, contrast_X=0.9)
ConvertXYZtoYUV(pColor=0)
Converttoyuv420()
ConvertBits(bits=10, dither=1)
Text("BT709 SDR 100 nits - Reinhard tonemapping")
tonemapped=last


ConvertToPlanarRGB(hbd, matrix="Rec2020", interlaced=false)
Cube("C:\Programmi\AviSynth+\LUTs\PQ_to_BT709_v2.cube", fullrange=true)
Converttoyuv420()
ConvertBits(bits=10, dither=1)
Text("BT709 SDR 100 nits - FranceBB LUT")
lutted=last


StackVertical(original, tonemapped, lutted)

If you like the last one, then I strongly suggest you to check this out: https://forum.doom9.org/showthread.php?t=176091

[LouieChuckyMerry]

Boulder: Thanks for your reply. I do have an nVidia GPU and a license for DGIndexNV, so I'll attack your suggestion ASAP.
_____________

FranceBB: Thanks again for your help. Your latest suggestion looks good but I'll need a goodly stretch of free time to wrap my head around it.
_____________

I should have time this weekend to work on the above, possibly (but doubtfully) earlier. I really appreciate the help .
_____________

Edit: FranceBB: I took a quick look at your last link and, wow, that's really cool! Of course, I understand it intellectually but not really any of the details .

[jpsdr]

New version, see first post, but nothing big...