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Canon EOS Crop Sensor for HD
APS-C sensor cameras including the 80D, 70D, 7D Mk. II, 7D, EOS M and Rebel models for HD video recording.


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Old September 3rd, 2009, 03:01 AM   #1
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Aliasing Artifacts

Reference beta footage from Anton Nelson on Vimeo:

Canon 720P 50FPS BETA FOOTAGE on Vimeo

Canon 7D 1080P 24FPS (beta footage) on Vimeo

Original 1080 & 720 files available to download for registered Vimeo users.

On download of the 720 50fps video, look at the jaggies around the edges of the metal sculpture, compared with the 1080 version.

The 1080 version looks very similar to the aliasing artifacts on the 5DMK2 around the edge highlights.

Of course this is a beta model.

Full res grab attached:
Attached Thumbnails
Aliasing Artifacts-canon7d.jpg  
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Old September 3rd, 2009, 07:27 AM   #2
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Wow, I don't see the technical problems, I see wonderful images with very little artifacts. Moving water is pretty hard for AVCHD...
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Old September 3rd, 2009, 10:26 AM   #3
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Originally Posted by Xavier Plagaro View Post
Wow, I don't see the technical problems, I see wonderful images with very little artifacts. Moving water is pretty hard for AVCHD...
Xavier it's not the codec or general compression but the in camera scaling.

see pic below.
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Aliasing Artifacts-canon7dzoom.jpg  
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Old September 3rd, 2009, 07:42 PM   #4
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Hi James. I can see the antialiasing scaling artifacts, but to me they are not as nasty as the blocking artifacts at the bottom right of the picture, in the out of focus area. It's not obvious in the stillshot, you need to look at the moving video. If this footage is really direct from the camera it doesn't look very good at all for anyone who is looking for shallow depth of field with attractive bokeh.

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Old September 3rd, 2009, 08:03 PM   #5
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At first I was going to put this off to sharpening artifacts, as it does seem that these clips are at least moderately sharpened (probably in-camera). then I checked out some new clips rob galbraith posted today (the shots of the viewing platform engulfed by waves)

Rob Galbraith DPI: Autofocus, video and more

his 1080 clip appears to be completely without sharpening...yet the aliasing in the 720 clip is even more pronounced than those mentioned in this thread...to my eye, they look more like upscaled 16:9 480p clips than native 720 clips..

Lets hope this is a pre-production issue.
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Old September 3rd, 2009, 09:24 PM   #6
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Yeah it is there on 720P footage, I don't see much on 1080P, hopefully it is not there.
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Old September 4th, 2009, 01:37 AM   #7
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Originally Posted by Barry Goyette View Post
his 1080 clip appears to be completely without sharpening...yet the aliasing in the 720 clip is even more pronounced than those mentioned in this thread...to my eye, they look more like upscaled 16:9 480p clips than native 720 clips..

Lets hope this is a pre-production issue.

Agree the 720p from Rob looks terrible.

I have just downloaded Philips 720p video from Vimeo. Looks good, blascks look a little hard and obviously the full frame and shallow DOF mask any perceptual resolution. But in shot 01:39:28 you can see a few jaggies on Philip's off cuts in the sink.

I wonder when changing from 1080p to 720p does the camera use the same picture profiles with custom settings?
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Old September 6th, 2009, 01:41 AM   #8
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It seems Canon has left the known problems of 5DM2 unfixed in this model so I wonder whether 7D gonna pass BBC's test.
So far 5DM2 footage is not approved by BBC for serious TV production due to these issues:

http://thebrownings.name/WHP034/pdf/...on_5D_DSLR.pdf
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Old September 6th, 2009, 06:30 AM   #9
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Originally Posted by Zsolt Gordos View Post
It seems Canon has left the known problems of 5DM2 unfixed in this model so I wonder whether 7D gonna pass BBC's test.
So far 5DM2 footage is not approved by BBC for serious TV production due to these issues:

http://thebrownings.name/WHP034/pdf/...on_5D_DSLR.pdf
This is not accurate. A broadcaster can ban a camera from their own production. But how can a broadcaster ban footage from any capture device? How can even guess from where the footage has been produced?

This camera produces high quality professional footage to any broadcaster in the world if you know what you're doing. As matter of fact, as it happens with any digital camera since dv.
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Old September 6th, 2009, 11:28 AM   #10
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And, the 5DMKII has been used as a second camera on at least one Hollywood production I know about, probably more. Networks only want good quality footage within broadcast tolerances (ie., exposure, etc.) on whatever formats meet their requirements.
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Old September 6th, 2009, 12:28 PM   #11
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Originally Posted by James Miller View Post
Xavier it's not the codec or general compression but the in camera scaling.
Are we concluding that the 720p is scaled up and actually sampled smaller?

I have seen Philip's film many times now and don't see really anything I don't like. I know we see the post grading and recompression and I am curious to see his raw footage. I see slight blockiness in the out of focus regions, but doesn't seem any worse than HDV and the horrid chromatic aberration on my first HD100. I just don't want jagged lines!
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Old September 6th, 2009, 03:03 PM   #12
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I took the Galbraith footage, and converted it using Cineform's Neo Scene.

It looks like Cineform is changing the levels, as with the 5D footage, giving the footage more detail in highlights and in the shadows.

Second, there may be some improvement in both the 720 and 1080p material with respect to aliasing an moire. But I will let you judge for yourself. See the attached grabs.
Attached Thumbnails
Aliasing Artifacts-thunder1080orig.jpg   Aliasing Artifacts-thunder1080cineform.jpg  

Aliasing Artifacts-thunder720orig.jpg   Aliasing Artifacts-thunder720cineform.jpg  

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Old September 6th, 2009, 08:35 PM   #13
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Originally Posted by Chris Barcellos View Post
It looks like Cineform is changing the levels, as with the 5D footage, giving the footage more detail in highlights and in the shadows.
Cineform is changing the levels as compared to what? From what I've seen, the older version of Quicktime clips the blacks. The newer version raises the gamma. Cineform, on my system decodes properly and sets the levels to 16-235. You can also get the correct levels by re-wrapping the MOV files in Quicktime to M4V (or is it MP4?) and applying the computer to studio filter in Vegas.

Take a look at the histograms and you should be able to see what's going on.
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Old September 7th, 2009, 03:12 AM   #14
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Originally Posted by Chris Barcellos View Post
I took the Galbraith footage, and converted it using Cineform's Neo Scene.

It looks like Cineform is changing the levels, as with the 5D footage, giving the footage more detail in highlights and in the shadows.

Second, there may be some improvement in both the 720 and 1080p material with respect to aliasing an moire. But I will let you judge for yourself. See the attached grabs.
Chris,

In your 720 orig and cineform grabs, are those from exactly the same frame? The water streaks from the splash look significantly different.
If they are then the recompression is doing a lot of changes.

Ted
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Old September 7th, 2009, 04:43 AM   #15
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Ted:
I forgot and pulled that frame from the end of the clips.. Cineform actually retimes, so I think that is why I was off. I will recheck.
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