DCP poor quality?

[JST01]

Hi,

I'm trying to create a 4K Scope DCP from a ProRes 4444 12 bit file and I'm kind of surprised by how the JPEG2000 compression is destroying the image.
Here are some examples: (please ignore the slight color and contrast differences, that's a different problem I'm trying to tackle)

4444.jpg

ProRes 4444 (original/source used to create DCP)

DCP.jpg

DCP @200mbps (viewed in fullres in the DCP-o-matic player, but no differences in other players)


I know it's mostly caused by the film grain in the image, but I can't believe the professional standard for cinema would handle this so poorly?
Even a simple H264 targeted for use on web has more detail than the DCP:

H264 50mbps.jpg

H264 @50mbps


What am I doing wrong here?
Thanks!

PS: is that white bar on the bottom of the DCP-o-matic player there for everybody? I don't see it when viewing the DCP in other players, so it's not part of the film.

[Carsten]

Hmm. Not sure if I see the differences as drastic as you do. If you are actually trying to reproduce 4k color noise - that is certainly the worst for J2K to tackle.

Maybe you can extract a single image from your source footage? I suggest taking a VLC video snapshot from your ProRes - NOT a system screenshot!

Then, load the 4K DCP (the 4k MXF file) into VLC, and create another video snapshot from the same (or close) frame. Load both of them up here.

You may need to set VLC to create PNG snapshots if necessary (may default to JPEG, which is unsuitable for obvious reasons).

[StephW999]

Hi,
it's strange .
I had fun encoding your image 4444.jpg with 2 different encoders at 200 Mbit/sec in a FLAT 4K container. (without RGB>X'Y'Z' conversion). The two jpeg 2000 files show no visible damage. (see attachments)

[JST01]

Hmm. Not sure if I see the differences as drastic as you do. If you are actually trying to reproduce 4k color noise - that is certainly the worst for J2K to tackle.

Maybe you can extract a single image from your source footage? I suggest taking a VLC video snapshot from your ProRes - NOT a system screenshot!

Then, load the 4K DCP (the 4k MXF file) into VLC, and create another video snapshot from the same (or close) frame. Load both of them up here.

You may need to set VLC to create PNG snapshots if necessary (may default to JPEG, which is unsuitable for obvious reasons).

If you're not already: you might want to open the stills in fullscreen a new tab and compare between tabs - and I might definitely be picky, but I just didn't expect DCP to clearly do worse than H264.

I extracted a single frame like you said from the DCP and the source via VLC (set to png), strangely VLC shows the correct colors in the player but the snapshots coming out are both different and wrong.
I'm getting an error if I upload any picture bigger than 5mb on here, so I had to convert all .png's to .jpg first. (in PS using preset 8 - high, they're visually the exact same, I checked)

DCP.jpg

DCP @200mbits (via VLC)

Source VLC.jpg

ProRes 4444 source (via VLC)

Source Correct.jpg

ProRes 4444 source with correct colors (via AE)

Now, although the color differences are annoying; if you compare the bottom right corner you can see how mushy the DCP becomes in comparison to the source. In playback I feel like it's even a little more noticeable too.
I might have to resort to using a different type of film grain. I already tried going monochrome and less contrasty/heavy, but there still seems to be quite a bit of compression.

Hi,
it's strange .
I had fun encoding your image 4444.jpg with 2 different encoders at 200 Mbit/sec in a FLAT 4K container. (without RGB>X'Y'Z' conversion). The two jpeg 2000 files show no visible damage. (see attachments)

Thanks for trying!
If I export the ProRes 4444 source frame from above with a J2K compression via Photoshop it's also not nearly as compressed as the frame from the DCP, unless I lower the 'quality' slider all the way down (which surely would be a lot less than the 200 mbps I used for the DCP) Very strange indeed..!

[Carsten]

This is again created from your first ProRes Image downloaded in 3840/2100 and compressed in DCP-o-matic 4k/flat at 200MBit/s. Loaded into VLC and created a video snapshot. Of course, using the current version of DCP-o-matic player, you can as well save the current frame to either PNG or JPEG.

No scaling applied in DCP-o-matic (padded from 3840/2100 to 3996/2160 with black)
I also made a 500MBit/s version, but there was hardly any difference between the two.

https://drive.google.com/file/d/10El7BM ... sp=sharing

Now, wondering wether your viewing environment does something wrong - or maybe it's a problem with DOMs/FFMPEG ProRes4444 decoder. Can you create an uncompressed single frame from your master, e.g. TIFF, and compress that in DCP-o-matic?

Now, admittedly, in your first post above, in your DCP-o-matic example, the color noise or grain indeed is lost completely. But, as your Image is JPEG, I can not be sure wether that has happened because of the JPEG compression - because, JPEG does not like color noise. Explicitly, JPEG mostly is not 444 (typically, subsampling is applied), so, colour noise at the pixel level will always be smoothed.
In my examples created with DCP-o-matic at 200MBit/s and 500MBit/s from your ProRes4444 sample - I do notice some compression, but the color noise is retained. So, why do you see different results? Can you explain your workflow from ProRes4444 to DCP in detail? Which version of DCP-o-matic do you use?

I also include the DCP, you may try to look at it and check what you see and wether you are able to extract a frame without the issues you had:

https://drive.google.com/file/d/1I2UM6h ... sp=sharing

[JST01]

I extracted a frame from your DCP and I don't understand how yours is so much less compressed than mine.

I tried using an uncompressed TIFF as the source for the DCP, and it gives me the same amount of compression; so it's probably not a problem with the ProRes 4444 decoder. I understand JPEG might further compress the images, so here is the uncompressed TIFF used as the source, and the same frame exported as png directly from the DOM player:

TIFF source (might show up small/weird in google drive, both files may be needed to be downloaded for fair comparison)
https://drive.google.com/file/d/1HCSMP5 ... sp=sharing

PNG from DCP
https://drive.google.com/file/d/1IV5LGi ... sp=sharing

Again, bottom right corner, color noise is lost. Overall detail becomes smudgy.
It doesn't make a difference if I use a moving sequence (with different noise each frame) or one single static frame as source for the DCP, they both get equally compressed. (since JPEG2000 is intra-frame, this is correct)
I am also noticing a slight brightness reduction in the DCP, is this normal and expected?

My workflow from ProRes 4444 to DCP is quite simple; once the source is added I only change the JPEG2000 bandwidth to 200mbps, and do some changes to the ISDCF name. The ProRes 4444 is 4096x1716, 12 bit, 12 fps. All other settings in DOM are left untouched as they are correct as is.
I'm on version 2.16.62.

Maybe you could try the TIFF from my first drive link and put it through DOM 4K/scope?

[Jiyahana]

Try adjusting the JPEG2000 compression setting during the creation process. Experiment with higher bitrate or different compression profile to minimize the impact on film grain. Check your DCP o matic player is updated as the white bar might be a display issue specific to that player. On the other hand you can can use online application for better png o jpeg compressor application such as jpeg compressor it compress the images without losing their original quality.