Smoothing

Y

yoclay

Veteran
This is an open question for everyone (I have also posted this over at Cinema5D.com). This issue has been raised more and more frequently lately in other posts as a side issue. I have had the fortune/misfortune of looking at more than 200,000 frames from a shoot recently in order to use frame grabs for a print job for a magazine and what I have founding is a disturbing amount of SMOOTHING. This is definitely getting in the way of sharpness/detail and I am wondering it is coming from the H.264 Codec itself or from some kind of hidden firmware overlay in order to cover up aliasing and artifact issues (something which I have also seen controlled with sliders before in other cameras). What are other people's experience with this and is there anyway to reduce it ?

Thanks.
CB
 
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I'm not quite sure what you mean by smoothing. Could you explain more and put up screen-grabs maybe? Also, what kinda magazine prints video screen grabs? Maybe I misunderstood you. Is it a film making magazine?
 
What it's too soft? hehe I wish. Are you saying it looks a bit soft as compared to a raw still? There is a manual sharpness setting but most shooters still find it a little sharp at it's lowest setting.

You looked at 200,000 frames! I hope you get paid by the frame
 
I am not allowed to post images from my Italian magazine job (model's rights issues) but an example of the texture issues I have seen might be depicted in the tree on the left of the first image in this post:

http://www.cinema5d.com/viewtopic.php?f=30&t=3195&st=0&sk=t&sd=a


If you were to take a software like Noise Ninja or use the Kodak DSLR cameras (which had no anti-aliasing filter) and put it on a noise reduction setting you would get a similar water color effect. This is often called smoothing in applications of this nature.


200,000 frames: that will teach me to stop trying to be cutting edge!
 
Ahh right gotcha. I suspected it was the H.264, it's a long GOP codec it compresses the picture over several frames so when you freeze a frame where there is movement you can get the "mud" look. It isn't really noticeable at 24/30fps but isn't pretty per individual frame. Did anybody think to shoot some stills too?
 
I haven't done any matching stills/videos, but I too suspected it was the codec. Just wondered if their was any noise reduction controls on this camera or hidden in the firmware which might be participating. (I asked Hudson this question too) The difficulty is that this image (according to the author) wasn't in movement! Pretty miserable if you ask me...
 
My understanding is the image is downsampled from 4k to 2k by means of line-skipping so I suspect there would be some kind of smoothing done to fill in the lost lines but I'm just speculating. Maybe someone can elaborate.
 
Interesting because it looks almost like the opposite, interpolating UP-wards from a smaller image...but I am not technically informed to know the truth...
 
Just received this reply from a seperate post I created on SMOOTHING in Technical Talk at cinema5D.com:


"This is the h.264 codec. You'll get it worse with lots of movement (so use a tripod if you can) It saves bandwidth by smoothing out areas of subtle contrast as it's easier to compress a single colour."
 
This is just as I thought, it is not being downres'd 4k to 2k, but rather UP res'd to full HD from: 960x540

See here:
http://www.cinema5d.com/viewtopic.php?f=14&t=2753

edit:
Hudson's response:

"That thread isn't relevant here -- the 960x540 vram buffer is not used for h.264 encoding. It is only for display on the LCD or HDMI output. The recorded movie file is full 1920x1080 resolution, and it is generated by horizontal binning on each scanline and throwing away two of every three rows. The display buffer takes that full resolution frame and decimates it by dropping every other row and column, which is why there is even worse aliasing on display."
 
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Hey man don't knock the HVX200, all those 35mm adapters were invented for a reason, and it was that camera. You are probably right though. :-)

Just read this though:


"That's not correct -- the 1920x1080 frame is split into two 1920x540 fields in a 1080i signal. In an interlaced signal each field has full horizontal resolution."

So who the f*** knows, I'm gonna have some lunch.
 
yoclay said:
Hey man don't knock the HVX200, all those 35mm adapters were invented for a reason, and it was that camera. You are probably right though. :-)

Just read this though:


"That's not correct -- the 1920x1080 frame is split into two 1920x540 fields in a 1080i signal. In an interlaced signal each field has full horizontal resolution."

So who the f*** knows, I'm gonna have some lunch.
Click to expand...


Dude I owned it.

There probably isn't a camera alive I haven't slepppt, ahhhh, I mean, owned for testing.... :-P
 
If I'm after a 720x 405 couldn't HDMI from 5Dii work for that?

Also someone said something about capturing with HD Link at 25fps is this possible?
 
Gawd that image is 'orrible.
You said you saw 1 good frame every 8 or 9.....I wonder, are you seeing the GOP structure?
But....we also see some wonderful looking cine off the cam so...
What did the moving footage look like from your shoot? was the degradation visible?
This has given me pause so I don't know how to spring, though budgetary reasons may force me to wait and see what canon do about further iterations of still / motion cameras.
Dave
 
Hi Dave,
First of all the footage still looks great from this camera, certainly far better than anything else in it's price range and far better than any 35mm adapter solution. These things are relative.

That said, I am not sure what produced this nasty result but it is not always like this. (this is not my work in the example, it is someone else's, because I must be careful with putting work with professional models online).

What I have noticed is a kind of smoothing or blending which can be more and less apparent in given situations. It seems generally the blame goes to the long form codec H.264. The GH-1 also does this and some refer to it as being occasionally "muddy" in appearance.

The one truly sharp frame every 8 or 9 in my own work, may also be related to the steadicam element of dealing with movement on several different axis as well as the subject being in motion as well. What I think is that this "smoothing" or compression may be exaggerated by motion blur as well...
 
Cheers yoclay, I understand about the release issues, and I was referring to the shots on cinema5d, I was probably a bit sloppy in my phrasing.
At the moment I have some budget worries (Building repairs needing doing, you know the sort of thing).
I wonder if Canon's next iteration will have an all I-Frame codec? I hope so.
Dave
 
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