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View Full Version : aliasing and moire?



jenningsp
06-25-2011, 11:02 PM
has anyone or is any one gonna do comprehensive tests???

this is pretty much the only unknown about this camera i think.

Postmaster
06-26-2011, 12:21 AM
I found aliasing in neon lights, but no visible moire.

Frank

David G. Smith
06-26-2011, 02:35 AM
I have ran across some moire while rack focusing through a window with a fine screen on it. Once the focus point changed either inside or outside of the window it went away.

speedracerlo
06-26-2011, 03:09 AM
Is there a difference between aliasing and moire? I have run across some of this stuff while focusing onto my computer speaker's finely patterned outer screen cover

David G. Smith
06-26-2011, 09:02 AM
Barry Green's article is one of the best explaining the aliasiing.

http://www.dvxuser.com/articles/article.php/20

Moire is also an issue with imaging systems and is usually seen as a multiple color artifact over fine detailed patterns.

http://en.wikipedia.org/wiki/Moiré_pattern

speedracerlo
06-26-2011, 01:39 PM
Thanks for that article David, thats a lot of info on aliasing

NeedCreative
06-27-2011, 05:39 AM
You're at risk got getting aliasing or moire on most sensors using a Bayer filter. But the fs100 and similar cameras show much less compared to DSLRs, so much less that, again comparatively speaking vs DSLRs in video mode especially Nikon and Canon, it's virtually none.

Edit: I want to qualify that I haven't seen moire patterns on the Fs100 at all, even with demanding footage such as distant brick, house siding, skyscrapers all in focus, etc. I've seen very minor fleeting aliasing that didn't look noticeable or unpleasant as noted Barry's article.

DM_rider
06-27-2011, 01:22 PM
I spent a week shooting on water and had no issues. Night and day compared to my 7d.

mandrean
06-29-2011, 12:38 AM
Me and my friend shot some landscape stuff from his NY apartment (skyscrapers and other buildings.) He used his 5D, I used my FS100.

The 5D footage had so much moiré on every brick wall that it would be unusable for anything other than web/YouTube stuff or maybe (?) static images in narrative work. But then the camera has to be dead still. Panning over the lower manhattan skyline was horrible... Our eyes instantly locked onto the hypnotizing and moving moiré patterns. They catch all your attention instantly when panning.

The FS100 had no moiré what so ever. Day and night compared to the 5D.

I haven't done any aliasing tests yet though.

NeedCreative
07-02-2011, 08:41 PM
The FS100 had no moiré what so ever. Day and night compared to the 5D.


The lack of aliasing and especially moire is what drove me ultimately to the FS100. It was a deal breaker for me on the 5D2, T2i, 7D, etc. Hate it.

NeedCreative
07-02-2011, 08:42 PM
I spent a week shooting on water and had no issues. Night and day compared to my 7d.

Water was another place the DSLRs blew it consistently. I remember killing myself for a shot on the beach at sunset running down with a Glidecam, to get home and see all kinds of aliasing and rainbowing on the horizon where the water met the sky. I was SO annoyed. Never again :)

David G. Smith
07-02-2011, 09:09 PM
I ran into some more issues with moire on my FS100 again due to window screens today. Other then that, the camera is so much better than a DSLR on that.

NeedCreative
07-03-2011, 09:06 AM
I ran into some more issues with moire on my FS100 again due to window screens today. Other then that, the camera is so much better than a DSLR on that.

As with all video cameras, one still has to be mindful of certain patterns that can cause moire. It's just thankfully far more rare in these cameras (i.e, like most other video cameras) than with the DSLRs which were, frankly, horrific in this area. Line skipping + an AA filter designed for stills = nightmare

Rick Burnett
07-03-2011, 02:21 PM
I've seen the Red One moire on window screens as well, not an easy thing to film.

I'm also getting ready to post an aliasing test on here with 7D, FS100 and AF100.

maarek
07-04-2011, 02:53 AM
I've seen the Red One moire on window screens as well, not an easy thing to film.

The only moire I have seen from RED material has always been caused by demosaicing to HD resolutions with a too fast algorithm. The original 4k files have no moire to speak of. I would bet that the window screens were completely clean in the original 4k size.

morgan_moore
07-04-2011, 06:34 AM
Im happy

36253

7d

36254

Big files : http://dslr4real.tv/index.php?option=com_zoo&task=item&item_id=80&Itemid=1

S (http://dslr4real.tv/index.php?option=com_zoo&task=item&item_id=80&Itemid=1)

Razz16mm
07-04-2011, 07:05 AM
3-chip cameras also exhibit aliasing and moire under certain conditions. Any digital camera with a fixed pattern of pixels will show aliasing at some resolution. Moire occurs when the fixed pixel pattern interacts with other patterns in the field of view that are near the same spatial frequency as the sensor. Video cameras are designed to minimize aliasing and moire effects via optical low pass filters in front of the sensor that filter out high frequency details that can cause the problem. This is because the artifacts are much more objectionable in moving images. Video from DSLR's exhibit more aliasing and moire because they are optically optimized for full resolution stills, not HD video, and the resolution subsampling for video adds to the problem if not done well.

Rick Burnett
07-04-2011, 01:03 PM
The only moire I have seen from RED material has always been caused by demosaicing to HD resolutions with a too fast algorithm. The original 4k files have no moire to speak of. I would bet that the window screens were completely clean in the original 4k size.

Nope, I looked at the original 4K file 1:1 and saw the moire there. It was red and blue chroma moire all across the screen. In addition, high spatial differences like the colors on chrome also produce aliasing on the RED when viewed 1:1. When reduced to 1080p the aliasing on the chrome goes away and the image is absolutely amazing. The colored moire however does not go away. That is the ONLY condition I've seen colored moire on the RED. Mesh screens of course are the absolute worst thing to try and film given the fine repetitive detail.

maarek
07-04-2011, 03:43 PM
Nope, I looked at the original 4K file 1:1 and saw the moire there.

Maybe the demosaicing was at half quality?

FelixGER
07-04-2011, 04:38 PM
I just bought the german video magazine "Videoaktiv Digital" and they meassure the vertical resolution at 671 line pairs (horizontal 660 lp)

Isn´t that a little low (below 720p) ? They also write the F3 resolves over 300 lp more!

Edit: Jesus! A few pages further they test the new Canon Legria consumer camcorders. The resolve 794 and 960 line pairs....For 750 and 900 Euros...
The Canon 600 D was measured at 704 lp vertically. More than the FS100 ?! This can´t be right!

NeedCreative
07-04-2011, 09:12 PM
Speaking of window screens...

36284

This example is particularly bad (FS100). One thing you notice however is the lack of chroma moire, which is nice at least. The 5D/7D shows horrible chroma aliasing and moire on the simplest of patterns. It's easy to forget that all video cameras can do this with extremely fine patterns, especially CMOS sensors. Have to go to film to get rid of it completely. The thing is, DSLRs showed it on relatively "chunky" patterns like bar codes, horizons, water, bricks, etc. where the video cams have no issues. The aliasing & moire points on the true video cams is with extreme detail. I'm tired but I think that's the gist. Razz explained it best above.

David G. Smith
07-04-2011, 09:28 PM
Speaking of window screens...

36284

This example is particularly bad (FS100). One thing you notice however is the lack of chroma moire, which is nice at least. The 5D/7D shows horrible chroma aliasing and moire on the simplest of patterns. It's easy to forget that all video cameras can do this with extremely fine patterns, especially CMOS sensors. Have to go to film to get rid of it completely. The thing is, DSLRs showed it on relatively "chunky" patterns like bar codes, horizons, water, bricks, etc. where the video cams have no issues. The aliasing & moire points on the true video cams is with extreme detail. I'm tired but I think that's the gist. Razz explained it best above.

Yeah, the Canon ASP-C cameras are horrendous, compared to the FS100. I just moved from down south where dang near everything was made of brick. It was a nightmare to shoot outside.

David G. Smith
07-04-2011, 09:31 PM
I just bought the german video magazine "Videoaktiv Digital" and they meassure the vertical resolution at 671 line pairs (horizontal 660 lp)

Isn´t that a little low (below 720p) ? They also write the F3 resolves over 300 lp more!

Edit: Jesus! A few pages further they test the new Canon Legria consumer camcorders. The resolve 794 and 960 line pairs....For 750 and 900 Euros...
The Canon 600 D was measured at 704 lp vertically. More than the FS100 ?! This can´t be right!

You may want to post that as a separate thread; I am sure that it will get a lot of responses. I am of the opinion that there is much more to pretty pictures than test chart resolution results, and the FS100 has a whole bunch of that much more.