Attila Bakos

1 hour ago, Andrew Reid said:

Here is a ProRes LT clip at infinity

https://we.tl/t-Di1du9K61X

Will try and get more footage today but the weather has been diabolical.

Finally some noise in the Cr: https://www.dropbox.com/s/mesy1evzib28hb2/DSCF0234_Cr.mov?dl=1
Noise is good in this case.

When you have a chance to do more, please use 422 instead of LT, I was told that the difference in quality was noticeable in the X-H2(s), and minimal between 422 and HQ.

I downloaded the 8K video sample from the bottom of this article: https://www.photographyblog.com/previews/fujifilm_x_h2_photos
It's 7680x4320 10bit 4:2:0 H.265 29.97fps, but only 100Mbps.
4:2:0 means that the chroma resolution should be 3840x2160.
So I put the clip on a 3840x2160 timeline, and on the right side you see the Cr channel with added contrast for better visibility: https://www.dropbox.com/s/e04fm6oc5ac9qbz/X-H2_chroma.mov?dl=1

I'll let you judge this, but I don't like what I see. Higher bitrate might help, or ProRes as well, but the chroma processing is still here with us 🙂 And this is not even F-Log where the issue was more prominent in the past.

Thanks, but it is hard to judge based on this shot. I need something far away at infinity focus, something like I posted earlier, if that's possible. And please shoot it in F-Log, or F-Log2.

Haha, I started reading this topic today and in the middle if it I wanted to ask you guys for some footage. Now I don't even have to, that's awesome 😄
Some distant forests would be nice, like in this example: https://youtu.be/7-RHHAUuI6s?t=466
Autumn is great for testing this kind of stuff.
And yes, h.265 and ProRes please.

16 hours ago, Jay60p said:

but I still don’t know what you meant by “the reason is known”.
Have you come to a conclusion?

I meant the reason for the color loss, which is the chroma smoothing. The reasons for the chroma smoothing at this extent I don't know and as you said, we may never know.

14 hours ago, Jay60p said:

What I means is, you also see it as a compression issue?

I wouldn't say this is a compression issue. This is not something caused by compression algorithms, this looks like some kind of smoothing, tupp already shared some thoughts about that in this thread:
https://www.eoshd.com/comments/topic/60753-color-detail-issues-in-fujifilm-video-files/?do=findComment&comment=471363

11 hours ago, Jay60p said:

Maybe this allows for more green or luminance detail for any chosen data rate.

In my video there is a section where I create a 100Mbps H.265 file from a 3584 x 1730 5D3 raw source and compare it with the 400Mbps Fujifilm file. While it's slightly less pixels than Fuji's UHD, the 100Mbps one is close to indistinguishable from the raw and the Cr channel is very detailed. And I didn't use some well optimized x265 encoder, I created the 100Mbps file in Resolve with GPU acceleration. When you put this next to Fuji's recording which has 4x the bitrate it becomes clear that there must be some purpose to the chroma smoothing other than preserving bandwidth for the luma channel. And I also mention in the video that I checked many files from other manufacturers (some of them have the same amount of luma detail and less bitrate) and didn't see this kind of chroma processing.

@Jay60p This issue is mostly about video, and at this point no further tests are needed, the color loss is there, and the reason is known. And to be honest I don't think we'll get a fix for this, not for the X-T3/X-T4. I'm still not sure about the X-H2s, it seems to be better but I only received a few, not really ideal samples.
And I will say this again, 99% of the Fuji shooters won't ever notice this, so I don't want to take away the joy of shooting with a Fuji camera, but the issue is valid nonetheless.

17 hours ago, Jay60p said:

1) I find the Cr channel completely useless for evaluating the chroma resolution or any other color quality of the X-T3. It is quite bizarre and completely misleading. Instead, study the usual RGB channels which appear completely normal and are as detailed as the actual full color photo. There is no red resolution being lost in the Red RGB like there appears to be in the Cr channel. I’m guessing the Cr channel is useless for image manipulation too, which may be why it was so hard to find an App which would display it.

Quite the opposite, this is what my video is about. There is no RGB in the original file, only YCbCr. RGB is constructed from YCbCr. The Red channel you see in Resolve/Premiere/etc is detailed because it is constructed from Y and Cr. Since Y is full resolution and very detailed, the resulting Red channel will be detailed as well, even though Cr is heavily processed and has less resolution. So if you want to know why your image lost colors in detailed, colorful areas -even though you see a detailed red channel- then you have to go back to the original channels and examine them. And that is Y, Cb, and Cr.

24 minutes ago, androidlad said:

Thanks. There seems to be very little, if any, difference between X-H2s and X-T3 in this clip.

The X-H2s is better, less blocky, but I was expecting a bit more as well. Maybe ProRes internal is better, but the guy who provided the clips doesn't have a CF express card so we couldn't test that. When he gets one he'll send me another comparisons. What I could test is ProRes RAW HQ external, and it's really good, but it's 15GB for one minute.

Okay, for those who find this kind of stuff interesting, here is a comparison of Cr channels (with added contrast for easy visualisation) from the C70, X-T3, and X-H2s:
https://www.dropbox.com/s/pbfjdx4c2zxhhzq/chroma_compare.mp4?dl=1

C70 is C-Log3, 100Mbps
X-T3 is F-Log, 400Mbps
X-H2s is F-Log, 360Mbps

There is definitely an improvement over the X-T3.
(I only received this files from someone, so I can't do other comparisons.)

Ignore my comment about the X-H2s having better chroma channels. Just received the same clip shot on an X-T3 from the guy who provided the X-H2s clips, and the chroma channels are good on the X-T3 too, at least in this shot. More extensive testing is needed. And I might just as well upgrade my X-T3 to the latest firmware and re-test it, who knows... 🙂

I just had a chance to take a look at some X-H2s originals shot in F-Log and F-Log2 in H.265, and it seems to me that the chroma smoothing is way less aggressive in this camera. It's still there, but it won't cause problems I think. This is just my first impression, not a deep analysis. And now you can completely get rid of the smoothing by shooting raw to an external recorder, I tested this with a ProRes RAW HQ clip. What I couldn't test is ProRes internal.

I also noticed that the H.265 files are now tagged with the BT.709 matrix coefficients instead of the BT.601. This will definitely solve some interpretation issues. One small downside is that the files are no longer full range (at least the F-Log and F-Log2 originals I received), they only use the limited range, so we lost some precision here.
 

28 minutes ago, androidlad said:

It also means that the F-log banding/colour botch issue still exists, also for F-log2.

I want to see badly how the chroma channel of F-Log looks like on this new body, but noone seems to have shared any originals. Let me know if you find any.

1 hour ago, androidlad said:

Because the photosenstive layer of the new X-Trans V HS is essentially the same as X-Trans IV, hence their colorimetry is the same so F-log implementation was copied over.

Well, then my LUTs work for the X-H2s as well, thank you Fuji 😄

Just noticed that the official F-Log LUTs for the X-H2s are exactly the same as for the X-T3/4. Even the Eterna LUT, which is a well defined look. If that's the same, then the F-Log source that it's applied on has to be the same as well. Makes me think... did Fujifilm tweak color data coming from this new sensor to match X-Trans IV sensors, or the sensor is not that different after all?
I mean, the F-Log LUTs for X-Trans III and X-Trans IV are clearly different, why are they the same for X-Trans IV and the new X-Trans CMOS 5 HS?

5 hours ago, Django said:

What about the Fuji LUTs for Canon Log?

I have an EOS R so it will come eventually. I'm also saving up for an R5C and then I can do something for C-Log3 as well.

5 hours ago, TheRenaissanceMan said:

Honestly, that's completely fair re: F3. It's a pretty niche market. 

 

So these are tailored to specific cameras, not just the color space + gamma? That's amazing. I'm assuming that means I can't just use a color space transform to put an incompatible camera into an appropriate color space, or at least wouldn't be guaranteed optimal results?

Yes the packs are tailored for specific cameras, I take about 10k color samples from each camera and from these measurements I create LUTs using my own engine. It's quite a long process.

17 hours ago, TheRenaissanceMan said:

I was talking about the Fujifilm Emulation LUTs, for which you listed several other formats. 

Ah I see. To create Fujifilm Film Simulation LUTs I need to have the camera for 1-2 weeks, and I don't know a single person in my area who owns it. The other thing is that it takes quite a lot of time for me to create these packs so I mainly go for cameras with large user base. In this regard I'm not sure about the F3.

16 hours ago, TheRenaissanceMan said:

This is great! Any chance of an SLOG1/SGamut version for us F3 users?

But that's already there in Resolve:

New ACES IDT packs are released:

• Leica L-Log/BT.2020
• Fujifilm F-Log2/F-Gamut

You can get them from here: https://colorizer.net/dev/index.php?op=aces

The Fuji one I did almost blindly, I couldn't get my hands on original F-Log2 clips yet, but since the data sheet is already out I created this package anyway. I used youtube framegrabs for verification and I can already see that if you bring F-Log and F-Log2 to the same contrast, the latter has more saturation, especially in the yellow-red area. And greens are a bit more yellow, foliage seems to be warmer.

26 minutes ago, androidlad said:

It's not fake.

Nobody said it IS the sensor of X-H2S, which is based on that sensor but with Fujifilm's customisation.

And nobody here said it's not, yourself included. A little explanation would have helped, as always.

On 6/6/2022 at 7:20 PM, androidlad said:

This turned out to be fake, if Fujirumors is to be believed:
https://www.fujirumors.com/update-imx671-is-not-the-sensor-of-fujifilm-x-h2s/

On 2/23/2022 at 3:40 PM, Andrew Reid said:

What impact if any does Color Chrome Effect have on this in the Fuji menus?

Is it possible Fuji's processing by default blurs the chroma channel so that dialling in certain film simulation settings brings it back and changes the look?

It must be on purpose they have done this.

Isn't Color Chrome for images only? I don't see how I could enable that for video on my X-T3.
My feeling is that the processing is there to hide something, not to enable something.

@tupp nice analysis, I really have to take a look at Darktable again sometime 🙂

26 minutes ago, Andrew Reid said:

@Attila Bakos

Do you mind if I draw attention to your video on the blog's main page? Let's get Fuji's attention.

Not at all! Do you plan to include info from the Petapixel article as well, or link that article? With the information there my video makes more sense.

Great... I'd rather have an OLPF and slightly less overall resolution than slightly more luma and noticeably less chroma. Or at least they could allow us to modify/switch off the chroma NR.