abrupt highlights clipping

[Piotr Wozniacki]

Originally Posted by Benjamin Eckstein

I almost feel like this is someone saying I filmed a person standing with their back to a window when it is bright out and I cannot expose their face properly without blowing out the background. In this situation it looks as if either the sky will be properly exposed or your darker foreground will be properly exposed. If the shot works better with cine (as it would) use that. I don't think this is a problem with the camera. We are given a wide range of image control options with this camera and many of them need to be used to optimize different image situations.

Benjamin, let me repeat again: I perfectly understand no camera will give me both background and foregrounf perfectly exposed and saturated if the backgroud is brighter, and this thread (and my problem) is NOT about this obvious phenomenon. What worries me are the patches I'm getting on the sky in all iris settings apart from the two extremities (upper left and lower right). The patches are tightly surrounding the foreground trees, and not necessary the brighter/darker areas of the sky itself (like the clouds). And this is a flaw to me.

Tomorrow I'll reset all Bill's "truecolor" matrix settings, and repeat the experiment with just the basic Hisat matrix and STD3 gamma. If the patches are gone, the culprit will be narrowed to the matrix pairs setting. BTW, I'm still uncertain how to interpret them, so please somebody explain to me in laymen's terms what increasing/decreasing does to the following matrix pairs values:

R-G
R-B
G-R
G-B
B-R
B-G

TIA.

[Paul Joy]

That does look very strange Piotr. Do you have any other processing happening on the camera such as skin tone detail or col correction etc?

It looks as though the camera is handling the light around the branches differently to the rest of the frame.

[Piotr Wozniacki]

Originally Posted by Paul Joy

That does look very strange Piotr. Do you have any other processing happening on the camera such as skin tone detail or col correction etc?

It looks as though the camera is handling the light around the branches differently to the rest of the frame.

At last someone who can see what I'm talking about; thanks so much Paul! And no, I didn't engage skin/colour correction.

PLEASE, do me a favour and try to recreate this. The settings are Bill's "truecolor" PP:

Matrix---------------------on
Select---------------------hisat
Level...............................0
Phase..............................+6
R-G................................+75
R-B................................0
G-R................................-18
G-B................................-23
B-R................................-33
B-G................................+11

Color Correction..............off
White.............................off
Detail.............................on
Detail Level.....................0
Detail Freq......................0
Skintone.........................off

Knee..............................on
Auto knee......................on
Point.............................90
Slope............................0
Knee SAT level...............50

Gamma Level.................0
Select...........................STD3
Black............................-15
Black gamma.................-9
Low key sat..................0

TIA, Paul.

[Paul Joy]

I use Bills TC2 profile but I use the CINE1 Gamma. The closest shot I have is attached.

regards

Paul.

[Piotr Wozniacki]

Yes, all Bill's PP's are fine with cine gammas. The problem is only appparent with the STD3 one, which is the factory default and as such, shouldn't "offer" surprises like that.

[Bill Ravens]

Piotr...


Judging from the images you posted, everything looks severely overexposed. There's a lot that happens when things get that far overexposed...CA rears its ugly head, etc., etc.
Looking at this image in CS3, EVERYTHING is pushed to the right end of the histogram. Please excuse my bluntness, but, this image need to be canned. Go retake the image, watch the histogram when you take it, be sure the peak is well centered in the histogram. It's not worth any more time discussing it.

[Michael H. Stevens]

PIOTR: I have discovered what's going on here. I have reproduced your effect and with the CINE gammas and not just SRD3.

Like you I set up bare trees against a clear blue sky. Your case is particularly extreme as I think you have the sky way overexposed, but I got the same effect with correct exposure.

I don't how this works in the camera, maybe connect to the knee drop off, but in the areas where the silhouette trees are the software is recognizing an area darker than the surrounding area and the black stretch is dropping the effectice exposure in that area which brings out the blue in the sky!

[Bob Grant]

I just went back at looked at all those frame grabs.
What's happening is the fine foliage is acting like a ND filter, that's why you see remnants of the blue sky around the branches.
At a guess the blue channel is clipping and/or the chroma sampling is blurring out the fine detail so in the second grab you don't see the fine branches.

[Leonard Levy]

Have you tried turning the auto knee off for a start, maybe the auto knee settings are too extreme. i rememeber many years Sony sent a new camera that was top of the line, and the auto knee was going crazy . Most people I encountered just thought it was normal, but the affects were horrendous. I'll try to check my camera as well. its definitely not normal.

[Greg Voevodsky]

I agree that the shots are way overexposed and strange things are happening. That is why I always shoot this .6 to .9 ND grads on all exteriors with a mattbox. You can also adjust both the highlights and shadows knees to get an additional stop or two worth of detail off of the defaults.

In post, you can then add the contrast back in. I found the camera defaults in very contrasty situations like sunsets... were not very good, but adjusting the settings, made a huge difference...

[Michael H. Stevens]

To add to what Greg says I have found this camera just hates overexposure in high contrast situations. The Standard settings being high contrast of them selves make this even more so than with the Cine gammas that smooth extreme contrast out.

The consequence of this is that this camera likes a bit of under-exposure. If you expose so the EX1's histogram is at maximum width I guarantee you will have a poor over contrasty image. Cut back on exposure until the histogram covers the center 80% and you will see much improvement.

This is the reason I said previously in the pp thread that picture profiles mean nothing without stating exposure levels which is the same as stating what zebra level you use. I never use the default 100% - it over exposes despite this cameras super-whites. I set my zebras at 95% and make sure no zebras are showing except where I deliberately want the picture to blow. Bills profiles for example are set at top 100IRE and if I shoot my normal way with Bills profile it is too dark so in that case I will set my zebras at 100%.

[Piotr Wozniacki]

Originally Posted by Michael H. Stevens

I don't how this works in the camera, maybe connect to the knee drop off, but in the areas where the silhouette trees are the software is recognizing an area darker than the surrounding area and the black stretch is dropping the effectice exposure in that area which brings out the blue in the sky!

Originally Posted by Bob Grant

I just went back at looked at all those frame grabs.
What's happening is the fine foliage is acting like a ND filter, that's why you see remnants of the blue sky around the branches.
At a guess the blue channel is clipping and/or the chroma sampling is blurring out the fine detail so in the second grab you don't see the fine branches.

And this is exactly what I was trying to say in my poor English - thanks guys for confirmation, and the proper wording.

And of course I do know the sky IS overexposed, but this is noexcuse - sometimes you just have to everexpose the sky if something else is of more importance.

And no, I didn't change the default KNEE settings, so it's not the reason. I'll try and do it today to find some compromise to avoid this.

Anyway - a very important thing for Sony to address in the next firmware update!

[Piotr Wozniacki]

Originally Posted by Bill Ravens

Piotr...


Judging from the images you posted, everything looks severely overexposed. There's a lot that happens when things get that far overexposed...CA rears its ugly head, etc., etc.
Looking at this image in CS3, EVERYTHING is pushed to the right end of the histogram. Please excuse my bluntness, but, this image need to be canned. Go retake the image, watch the histogram when you take it, be sure the peak is well centered in the histogram. It's not worth any more time discussing it.

Bill,

The only severely overexposed frame is the upper left one, put here for comparison sake, and this one does NOT shaw the flaw I'm talking about - the sky is uniformly white...

The problem appears in the next 2 grabs, and is most severe in the properly exposed (balanced with the foreground) conditions.

The last grab (bottom right) is severely underexposed (if one wanted to properly show the foreground), and the problem vanishes again - the sky is blue not just directly behind the trees....

Do you understand my point now, or still think "It's not worth any more time discussing"?

[Piotr Wozniacki]

Originally Posted by Bob Grant

I just went back at looked at all those frame grabs.
What's happening is the fine foliage is acting like a ND filter, that's why you see remnants of the blue sky around the branches.
At a guess the blue channel is clipping and/or the chroma sampling is blurring out the fine detail so in the second grab you don't see the fine branches.

Bob,

It's been established that the KNEE setting have not been played with; do you think that the problem I showed might exagerrated by the settings I used (pls. see above post for details)? I don't think so, but then I confess I''m not quite sure how the specific colour matrix pairs are working (could you explain them to me, please?)

And one more thing to explain why I was so alarmed: the problem looks much, much worse in the actual moving video, as the blue remnants are not stationary - with camera movement, or any slight variation in exposure, they move around the sky as well, changing not just the location, but intensity as well. Heck, the patches look like they have life of their own, suddenly vanishing here to only appear there!

[Piotr Wozniacki]

Originally Posted by Michael H. Stevens

I never use the default 100% - it over exposes despite this cameras super-whites. I set my zebras at 95% and make sure no zebras are showing except where I deliberately want the picture to blow. Bills profiles for example are set at top 100IRE and if I shoot my normal way with Bills profile it is too dark so in that case I will set my zebras at 100%.

This is a very important point, Michael - as it confirms why I have noticed this undisputable flaw in highlights compression algorithm only after having dialed in Bill's profile. The same gamma (STD3) without matrix modification may look flattish compared to Bill's PP, but at least it allows to keep the sky safely below 100% and still have the darker picture areas exposed enough, and not oversaturated due to underexposing.

So, the conclusion is that if one is after more saturated colours, he better use one of the gamma curves and not saturate colours with the STD3 one!

With the V1 for instance, it's so obvious: if I want vivid punchy colours, I engage cine colour and cine gamma 1 (or even 2), and I'm good to go. Never saw a problem like this here (but I admit I never tried saturating colours with the non-cine gamma, instead for my in-hose, lowlight picture profile).