Moire effect and Aliasing

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markcurtisp

Member
I'm assuming people with good knowledge in cinematography would know this, what is the difference between the two,

in the student tv show I am analysing there is some bluring that appears on suit jackets and jumpers, etc which I am guessing is Moire?

then there is the same kind of bluring in the background of shots, e.g. window shutters, is this moire or aliasing?
 
Strickly speaking, aliasing refers to the false detail effects that you can get when a signal (in this case, an image) is sampled too low to correctly capture all of the details in the signal being recorded. Moire refers to the interference patterns that you can get when aliasing shows up on a repeating pattern, like a chain-link fence or some fabrics. Some other common effects of aliasing are stair-steps along lines that should be straight, or "sparklies" in areas of high-contrast, but non-repeating fine detail.

Do you have a screen shot of the show in question that you can post? That will make it easier to identify what you're seeing.
 
it doesn't really show up well in a screenshot the errors the shots have, it was shot in the 90s so the quality is poor and the sequence is shot in black and white, you get blurring in things in the background like bricked bridges and walls, i don't know if it's just the poor camera quality or if it is an actual error
 
Shot in the '90s? I couldn't say anything for sure without seeing footage, but you might be seeing interlacing artifacts.
 
Wesley Byram said:
Shot in the '90s? I couldn't say anything for sure without seeing footage, but you might be seeing interlacing artifacts.
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you may be right about that, the flicking/blurring is all over the wall in a shot like that and in the 2nd one it is just under the bridge tunnel to the left of the girls head.

just another question, do you know what a concatenation error is?
 

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markcurtisp said:
you may be right about that, the flicking/blurring is all over the wall in a shot like that and in the 2nd one it is just under the bridge tunnel to the left of the girls head.
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Well, nothing's jumping out to me. It looks soft in general, which one would expect from a 1990's video camera, assuming that this was shot on video and not film. Do you have access to the original tape, or are you working from a digital re-encode of the video? A low-bitrate encode can certainly cause blurring and/or blockiness in the footage.

markcurtisp said:
just another question, do you know what a concatenation error is?
Click to expand...

My past life as a (bad) computer programmer leads me to think that this is an error message being produced by some application, correct?
 
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