Aliasing - from Daniel Browning

B

Barry_Green

Moderator
Check out Daniel Browning's post over on DVInfo, describing some examples of how aliasing is polluting images, and why lots of people don't seem to care. Daniel shares my view that the current crop of DSLRs are delivering images with real resolved detail somewhere between SD and maybe 720P, and that the rest of the "sharpness" people are perceiving is actually aliased false detail. In this thread, he shows an example of an image with aliased detail vs. an alias-free image.

Interesting, because I think at first glance (and even second and third glance) most here are not going to notice or care about the aliases...

http://www.dvinfo.net/forum/1433387-post61.html
 
Interesting - especially the idea that what many are perceiving as sharpness is actually aliased false detail.

Though you're right - looking at those two pictures - most (myself included) are not going to care too much about the aliasing.

Like you mentioned in one of your testing threads - if you were intercutting this footage with something else, it might stick out like a sore thumb - but I think for projects that are shot exclusively on a DSLR, the aliasing isn't a dealbreaker (at least not for me... or my clients)
 
All of this conversation of charts and actual versus perceived detail is very strange to me. I guess it depends on what you're making, but in the narrative world resolved detail is way less important than what the image does for the viewer.

I am currently producing a feature film for the Internet that is backed by studio money (can't say which yet) which is being shot entirely by the 5d and 7d. The second I get clearance to release trailers/clips I will do so.

All I can say at this point is - is there aliasing? Yes, some. Does the footage blow the mind of everyone involved including veteran, high up producers, yes. The footage is incredible and will create a great film in the end.

What I'm saying is. May we always be critical of cameras (I personally very much was of my GH1), but may we also never lose track of why we own cameras in the first place.
 
I was wrapping my mind about this since my first narrative shots on the 5D and especially since I saw Barry test charts.

Yes the 5D/7D resolution is somewhere between SD and 720P, but the images look great despite the lousy bitrate, long GOP codec and low resolution.

I was asking myself why they look so crisp and dense?
Now I know it - aliasing artifacts. It´s like adding artificial noise in post, it does the same thing. Faking micro contrast and detail.

But as Daniel Browning said, it looks computer generated. Beautiful but somehow wrong.
Thats what I meant, when I said in an other thread that "all those DSLRs have a strong pronounced signature. You can see the signature of a RED if you have a trained eye, but the DSLRs signature jumps right in your face."

Now I know why. Thanks for the link Barry - finally I can sleep again.

Frank
 
Interesting post. Certainly percieved quality is subjective.

I think a still image comparison hides the aliasing issue. On subsequent frames on a real video it would look worse, or at least "unnatural."
 
PDR said:
Interesting post. Certainly percieved quality is subjective.

I think a still image comparison hides the aliasing issue. On subsequent frames on a real video it would look worse, or at least "unnatural."
Click to expand...
Meaning, you think a still frame hides how bad it looks, and if someone posted video in motion it'd look a lot worse? I totally agree.
 
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