HDR -> SDR conversion

These CUDA filters are packaged into DGDecodeNV, which is part of DGDecNV.
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admin
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Re: HDR -> SDR tonemapping

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You are welcome. It's always my pleasure.
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Re: HDR -> SDR tonemapping

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So, we have established that we need to do the 2020->709 conversion and the tonemapping all together on the GPU if we expect CUDA to give us good performance gains. So I have been researching how to do that. Here is my tentative plan for the 2020->709 part. If it pans out then tonemapping can be added. Please advise if I am planning anything stupid. I'm a bit of a dilettante in the colorimetry area, so...

Code: Select all

Convert HDR 10-bit in YUV420P16 to YV12

Step 1: Convert to P10.

Strip lower 6 bits (zeros)

Step 2: Convert to RGB

R = 1.164(Y-64) + 1.596(V-512)
G = 1.164(Y-64) - 0.813(V-512) - 0.392(U-512)
B = 1.164(Y-64) + 2.017(U-512)

Step 3: Linearize

R = R * R
G = G * G
B = B * B

Step 4: Map the gamut using inverse of rec 2087 matrix

R          1.6605  -0.5877  -0.0728     R
G      =  -0.1246   1.1330  -0.0084  *  G
B         -0.0182  -0.1006   1.1187     B
709                                     2020

Step 5: Gamma correct

R = sqrt(R)
G = sqrt(G)
B = sqrt(B)
clamp as needed

Step 6: Convert to 8-bit YUV

Y =  (0.257 * R) + (0.504 * G) + (0.098 * B) + 16
U = -(0.148 * R) - (0.291 * G) + (0.439 * B) + 128
V =  (0.439 * R) - (0.368 * G) - (0.071 * B) + 128

This can now be returned as YV12 for Avsynth+.
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Re: HDR -> SDR tonemapping

Post by Guest »

I am a complete rookie at the color thingy, but based on all the stuff I have read on the topic, before my eyes glazed over, your approach seems to be spot on from the format (2020 to 709) to the clamping of the levels to accommodate the 8 bit standard
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Re: HDR -> SDR tonemapping

Post by admin »

OK, good to hear. Of course, there are a lot of ways to map the out-of-gamut values back into range, but it seemed sensible to me to just reverse what is given for 709->2020 in REC 2087.

https://www.itu.int/dms_pubrec/itu-r/re ... !PDF-E.pdf
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Re: HDR -> SDR tonemapping

Post by Guest »

It does appear to be a logical approach
If
A>black box >B
then
B> inverse black box >A
Only in this case the black box is a known algorithm
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Re: HDR -> SDR tonemapping

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Earlier I was a bit concerned about whether an external Avisynth+ filter could change the video format, e.g., from YUV420P16 to YV12. Then I realized that is exactly what z_ConvertFormat() does. So I tried it and it is actually quite easy. So I now have a filter that just converts YUV420P16 to YV12 by truncating the lower 8 bits and it works fine. Of course without proper gamut mapping and tone mapping it is washed out as expected. But this forms the basis for implementing the process I gave a few posts up. So, well on the way to nirvana!
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Nginx
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Re: HDR -> SDR tonemapping

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admin wrote:
Tue Apr 24, 2018 7:37 am
Earlier I was a bit concerned about whether an external Avisynth+ filter could change the video format, e.g., from YUV420P16 to YV12. Then I realized that is exactly what z_ConvertFormat() does. So I tried it and it is actually quite easy. So I now have a filter that just converts YUV420P16 to YV12 by truncating the lower 8 bits and it works fine. Of course without proper gamut mapping and tone mapping it is washed out as expected. But this forms the basis for implementing the process I gave a few posts up. So, well on the way to nirvana!
Good Avatar. :lol:
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Re: HDR -> SDR tonemapping

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I have coded the proposed algorithm in a C-code filter, eliminating the calls to z_ConvertFormat() in the script. It works quite well. Surprisingly, the speed is almost identical to the existing DGTonemap(). It's surprising because z_ConvertFormat() is assembler optimized. But apparently that's canceled out by the fact that the script uses two z_ConvertFormat() calls. The image quality is comparable to what we have from the existing DGTonemap script. I expect to see a large speedup when implementing it in CUDA. Keep your fingers crossed.
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Re: HDR -> SDR tonemapping

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I have tossed out Hable/Reinhard and rolled my own locally adaptive tonemapping operator. Below is an example. Note the lack of blowout in the clouds and retention of detail there. Also, detail is retained on the dark areas of the left-hand rider. Detail in the hills is brought out nicely. To me, it nicely conveys the 'wow' factor of the original HDR. It's computationally more intensive but I think it's worth it and CUDA should give acceptable frame rates.

Here is the process (all done in C code for now):

* Convert full-depth YUV to 32-bit float RGB.
* Normalize R, G, and B to [0.0,1.0].
* Linearize with ST.2084 EOTF.
* Map the gamut from 2020 to 709 using the inverse of REC.2087.
* Tonemap with locally adaptive algorithm.
* Compress to 709 gamma.
* Scale to 0-255 and convert to YV12.


Image
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Dion
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Re: HDR -> SDR tonemapping

Post by Dion »

Amazing... :bravo:

When do we get to try this ourselves :)
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Re: HDR -> SDR tonemapping

Post by admin »

Thanks. I have to port it to CUDA to make it practical. Patience!
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Re: HDR -> SDR tonemapping

Post by Guest »

Looking very impressive :salute: :salute:
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Narkyy
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Re: HDR -> SDR tonemapping

Post by Narkyy »

Does porting to CUDA imply that it'll be integrated with DGSource and the indexing? Or still a standalone plugin?
Wondering as I can't currently use the indexing for HEVC :(

Thanks for the hard work :salute:
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Re: HDR -> SDR tonemapping

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Narkyy wrote:
Tue May 08, 2018 8:14 pm
Does porting to CUDA imply that it'll be integrated with DGSource and the indexing? Or still a standalone plugin?
Wondering as I can't currently use the indexing for HEVC :(

Thanks for the hard work :salute:
You're welcome.

It'll probably be a standalone filter requiring YUV420P16. The utility filters currently in DGDecodeNV.dll can be used independently of DGSource() and indexing, BTW, so even if I integrated it you could still use it. Why can't you currently use indexing for HEVC? No suitable nVidia card?
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Re: HDR -> SDR tonemapping

Post by Narkyy »

Yep, and from past support emails from a while ago I couldn't get the 970 to work with DXVA + Win10 for HEVC.
That sounds good then :)
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Re: HDR -> SDR tonemapping

Post by admin »

I have the initial port to CUDA completed with Reinhard tonemapping. It's running at 80 fps on HDR 3840x2160. Pretty good. Software mode runs at about 1 fps, so that's an 80x speedup.

I'll add the option for my local tonemapping and then give y'all a test version. I expect the frame rate to drop by about 25% but we'll see. I'll allow selection of the desired tonemapping operator.
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Re: HDR -> SDR tonemapping

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Can hardly wait, you are a busy one
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Re: HDR -> SDR tonemapping

Post by hydra3333 »

admin wrote:
Thu May 10, 2018 5:05 pm
I have the initial port to CUDA completed with Reinhard tonemapping. It's running at 80 fps on HDR 3840x2160. Pretty good. Software mode runs at about 1 fps, so that's an 80x speedup.

I'll add the option for my local tonemapping and then give y'all a test version. I expect the frame rate to drop by about 25% but we'll see. I'll allow selection of the desired tonemapping operator.
80x, wow.
local tonemapping ... copyrighted ? ;)

Thank you ... again :bravo:
I really do like it here.
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Re: HDR -> SDR tonemapping

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You're welcome. Actually, local tonemapping is a well-known thing, with several approaches having been tried. The challenge is to make it computationally feasible for video. I am using a histogram equalization approach.

I have a beta for y'all to try:

http://rationalqm.us/misc/DGHDRtoSDR_1.0.rar

Read the included text file DGHDRtoSDR_1.0.txt for usage instructions. Feedback will be gratefully received.

Some parts are not yet ported to CUDA. I am working on that and also improvements to the local tonemapping. I am getting ~80 fps (measured with AVSMeter64) with this version.
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Dion
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Re: HDR -> SDR tonemapping

Post by Dion »

Really brings out the background details atm.

DGHDRtoSDR(impl="255", light=50, equal=0)
Image

DGHDRtoSDR(impl="255", light=50, equal=10)
Image
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Re: HDR -> SDR tonemapping

Post by admin »

Thanks for your results. Try equal=15 or 20 to really bring out the details. I'm working on not amplifying noise in flat areas at those high levels of equalization.

I'm also curious to know your GPU, CPU, and attained frame rate.
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DJATOM
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Re: HDR -> SDR tonemapping

Post by DJATOM »

https://i.imgur.com/GJMK9wr.jpg
The flower looks distorted.

My script:
LwLibAvVideoSource("G:\SOURCES\MARI_TO_MAJO_NO_HANA_UHD\BDMV\STREAM\00001.m2ts")
ConvertFromDoubleWidth(bits=10)
ConvertBits(16)
DGHDRtoSDR(impl="255",light=90,equal=2)
DeBicubicResizeMT(1920,1080)
I've got near 14 fps with software decoder.

Upd: imgur used jpeg so it's not that visible on my first screenshot. Hope that one is better: https://i.imgur.com/hcihLxO.png

hcihLxO.png
PC: RTX 2070 | Ryzen R9 5950X (no OC) | 64 GB RAM
Notebook: RTX 4060 | Ryzen R9 7945HX | 32 GB RAM
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Narkyy
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Re: HDR -> SDR tonemapping

Post by Narkyy »

Had a quick go at it, here's some comparisons

SDR Image
Hable Image
Reinhard Image
DGHDRtoSDR(impl="255",light=50,equal=10) Image
DGHDRtoSDR(impl="255",light=50,equal=5 ) Image

Some other than default settings
DGHDRtoSDR(impl="255",light=100,equal=5) Image
DGHable(exposure=1.5, w=1.8) Image

Around 29 fps average for just the tonemapping at 3840x2160 with prefetch(2)
Ryzen 2700X, GTX 970
Script for speed test:
FFVideoSource("source.mkv", colorspace="YUV420P16")

DGHDRtoSDR(impl="255",light=50,equal=5)
trim(30000,35000)
prefetch(2)
I think it does a great job at keeping detail, a bit messy in darker areas though :bravo:
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admin
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Re: HDR -> SDR tonemapping

Post by admin »

Thanks for your testing.
The flower looks distorted.
Can you please give me a source sample that produces this? I can PM you an FTP if you need it.

Maybe I should put a CUDA resizer in there too as your scripted resize is losing you a lot of time.
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Re: HDR -> SDR tonemapping

Post by admin »

Thanks for your testing.
Narkyy wrote:
Sat May 12, 2018 2:48 pm
a bit messy in darker areas though
Can you please tell me what you mean by messy?
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