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View Full Version : ALIASING: 7D vs FS100 vs AF100.



Rick Burnett
07-03-2011, 03:29 PM
So, you want to know which camera is the worst and which is the best? I can tell you right now, guitar strings are one of THE hardest things to shoot. Because of that, it only made sense to push all three cameras. All three cameras shot the same lens. I pulled back on the AF100 to try and keep the guitar the same size. Remember, no test is perfect and this is just to show in a real world situation ALL three cameras will present aliasing. And, without doubt, the 7D very easily compared to the other two.

Like any good test, I am not telling you the names of which is which yet. There are some pretty easy clues as to who is who. I am including a link to the full jpg which I compared to the original footage to make sure the jpg wasn't introducing artifacts (and it is not).

http://asylumstudioproductions.com/images/ALIAS_TEST.jpg

All three cameras were set to their default detail. All three cameras shot at ISO400. The closest string (high E) is a perfectly straight non wound strip. All three were focused by hand with 1:1 on a smallHD.

Top 3 are 100% crops. Bottom 3 are same crops at 200%.

One thing I can say. I didn't expect to get the aliasing so easily on this shot with the AF or the FS. BEWARE OF STRINGS! :)

morgan_moore
07-03-2011, 03:39 PM
confused - each picture is different ?

But I guess the FS is the winner :)

Rick Burnett
07-03-2011, 04:30 PM
Each picture is a different camera. :) In this test, I don't see a clear winner.

mcgeedigital
07-03-2011, 05:16 PM
Nice test. If I were shooting strings, I'd use the ccd of my hpx500.

mcgeedigital
07-03-2011, 05:20 PM
I'd also be curious as to the results if the detail were turned down a bit.

Rick Burnett
07-03-2011, 05:24 PM
When I turned the detail down on any of them, it just softens the image so the aliasing does decrease in apparentness. Given the spatial color difference between the black and reflection of light off the strings, this is about as bad a situation that you can get.

That said, do please try to guess who is who. The 7D is probably the easiest to figure out, but there are two huge clues on the other images as well. :)

stevedocmaker
07-03-2011, 05:30 PM
I give up!

ROCKMORE
07-03-2011, 05:47 PM
Good myth buster.

FelixGER
07-03-2011, 05:52 PM
C: 7d !

GRENCH
07-03-2011, 06:24 PM
A is the AF100
B is the 7d
C is the FS100

OldCorpse
07-03-2011, 06:45 PM
A:AF100
B:7D
C:FS100

Now I looked at other answers: Grench beat me to it. I reached the same conclusions independently, but maybe we're both wrong!

ROCKMORE
07-03-2011, 11:29 PM
A:AF100
B:7D
C:FS100

Now I looked at other answers: Grench beat me to it. I reached the same conclusions independently, but maybe we're both wrong!

That sounds like a logical conclusion, but I wonder how much different the test would play out being able to remove sharpening and contrast with Cinestyle on the Canon and similar sharpening/contrast reduction on the AF100 and FS100. After all I don't think many of us are shooting with a default settings on any of these cameras with the advantage of flat profiles.
I've settled on CineStyle 0,-4, 0, 0 for just about everything.

Rick, I'm sure you're a busy guy, but if you still have the 3 cameras and you ever have a chance, it would be nice to know what the result would be.

maarek
07-04-2011, 03:49 AM
Styles or sharpening do not affect aliasing.

My guess:

A= FS100 (very clean, regular videocameras have about same amount of aliaising with straight lines)
B= AF100 (not much chroma noise, but the angle is such that it looks like it has more aliasing going on)
C= 7D (Because of chroma noise)

B & C are pretty interchangeable in those shots.

AGMedia
07-04-2011, 05:35 AM
A: fs100
B: 7d
C: af100

Although, I'd still pick a 7D over the af100 for anything.

Rick Burnett
07-04-2011, 01:21 PM
Styles or sharpening do not affect aliasing.

My guess:

A= FS100 (very clean, regular videocameras have about same amount of aliaising with straight lines)
B= AF100 (not much chroma noise, but the angle is such that it looks like it has more aliasing going on)
C= 7D (Because of chroma noise)

B & C are pretty interchangeable in those shots.

And you are absolutely correct. :)

A is much sharper than the other two, which makes sense. I find the FS100, while not as sharp as the F3, is definitely resolves more than both the AF100 and the 7D. The interesting thing is I normally shoot with the AF100 at -4 detail and vdetail, but for this test I let it be at 0. So in my typical shooting, you'd see the aliasing on the AF100 even less, but then, the image would be even more softer than it already is.

B is a slightly different angle as the lens sat a little higher up on the AF100 and I had to pull it back some. I tried to keep it as close as possible. I think the aliasing between the FS100 and AF100 look about the same. If I reduced the detail further on the FS100, it would start to blur the aliasing just as the AF100 is doing it.

Without a doubt, C is the 7D. I actually find it interesting that ANYONE would think that is the AF100. The AF100 does not generate ANY chroma noise. The FS100 can, but as you see here, not very easily, probably more so with VERY tight patterns like screens.

Not only is the 7D chroma aliasing pretty bad, notice the string is very broken up. The red/purple are REALLY changing not only the string appearance but on the wood grain detail as well. This is obviously not a good thing and very indicative of some of the problems you can have with the 7D and fine detail.

The 7D I shot with the settings I always use in it for everything I've done with it. I've not loaded the technicolor because I am not using it for video anymore, but regardless, aliasing is aliasing. It's still there regardless of the detail setting. The best you could do is in post, apply sharpening (or blur) to the images to try and match the same detail level and then compare what the aliasing looks like.

Walking away from this test, while I wish the AF100 and FS100 handled this a little better, I have no doubt that they are superior to the 7D results because the chroma component of the 7D aliasing actually changes the way things look. You wouldn't believe how hard it is to deal with in VFX shots when you've got dancing colors on an edge.

ROCKMORE
07-04-2011, 05:45 PM
If this is the worst case scenario it should make people shooting with a 550D or 60D pretty relieved that they can come close to the same image for around 15 to 20% the cost. A second or 3rd camera could a be more useful option.
Personally I have rarely come across aliasing and moire in the real world. Work around or luck, who knows.

Rick Burnett
07-05-2011, 11:48 AM
If this is the worst case scenario it should make people shooting with a 550D or 60D pretty relieved that they can come close to the same image for around 15 to 20% the cost. A second or 3rd camera could a be more useful option.
Personally I have rarely come across aliasing and moire in the real world. Work around or luck, who knows.

I think you misunderstood what I was implying, this is the worst case scenario for creating an aliased edge, this does not indicate all scenarios that aliasing occurs and with Canon DSLR footage, that is a HUGE range of situations. There are plenty of situations where the Canon continues to exhibit tons of aliasing where both the AF100 and FS100 show none.

And I bet you have more aliasing than you realize it because I thought the same thing too until I actually got an even better camera and started comparing the images. I've shot with the 7D since it was released, and the same for the AF100 and FS100. Two weekends ago we shot a short piece using my FS100 and the directors 7D. He called me while editing to tell me how amazed he was at the shots with the FS100. The images had more resolution, they were cleaner, the colors were better, and overall he just couldn't believe the quality. He told me he had to "dumb down" the FS100 shots just so the material would mix together for this, and that in the future, the 7D was out.

The best part about this test is the C is showing you the exact problems you get with Canon sensors. There is red all over the top of that guitar that did not exist. You can see the red tint in the 1:1. This happens depending on the source material with red or blue, and when the camera shifts a little, you see the moire/aliasing patterns dancing across the image. It's a HUGE problem in hair.

A 2nd or 3rd camera is not a useful option to me when I am having the same risk on all three cameras. Not to mention, the rolling shutter is almost twice as fast on the AF100 and FS100 as the Canon DSLRs. That is a HUGE difference. It really opens up your freedom in shooting which was clear to us on day one. Jello was practically gone. (Skew still is a concern).

I just quickly went though a bunch of our footage from our "Modern War Gear Solid" mini-series that was entirely shot with the 7D. Here are 3 great examples of chroma moire that we did NOT see during shooting, and that was using a 720P external LCD as well. That is the worse part about this because you CANNOT see these problems in the Canon cameras, only after.

http://www.asylumstudioproductions.com/images/moire1.jpg
http://www.asylumstudioproductions.com/images/moire2.jpg
http://www.asylumstudioproductions.com/images/moire3.jpg

The problem is, *knowing* when your fine detail in the image could do this is hard to know. Not every shot of the tactical vest had this problem. Not every brick wall. Not every couch pattern, clothes patterns, on and on and on. THIS is precisely what you can avoid with the AF100 and from my experience, the FS100 as well. Even the GH1 and GH2 do not have this problem, as they are SUPERIOR when it comes to aliasing. I too have shot with the GH2, and I have found in my experience it aliases before the AF100 and FS100, but WAY AFTER any Canon sensor. And I've personally worked with the 7D, 5D, 1D and T2I myself.

Is the improved image quality worth it? To me, without doubt. Just because I bought the AF100 or FS100 doesn't mean I couldn't easily just sell them if I was satisfied with the 7D quality. I am not. The difference in quality 1:1 on the same monitor is NOT subjective. It's clear as day, and everyone that I work with who has had the opportunity to shoot with the FS100 or AF100 has always left trying to figure out what they are going to do to get one into their arsenal. I've done MANY shoots with both me using either the AF100 or the FS100, so it's not like this is a one of occurrence.

Now don't get me wrong, the 7D to me is still a great camera and for A LOT of people I personally think it makes a lot of sense. A $5k camera is not for everyone and I think the end really needs to justify the means. I do a lot of visual effects work so I need my images to be cleaner. If I could afford the F3 with SLog or even an Alexa, both would make my work even easier, but like some who cannot justify the cost of the AF100/FS100 I cannot justify the cost of the F3/Alexa/Epic/RedOneMX. We all have to decide where our satisfaction with money vs performance plays out.

FelixGER
07-10-2011, 12:37 PM
I tweaked my picture profile and accidently crashed into SERIOUS aliasing problems!
Watch the roof.

I uploaded the MTS File. This was shot with Detail set to -7

http://www.steinhardtverlag.de/Felix/00093.MTS

Postmaster
07-10-2011, 01:02 PM
Wow! So what would you say is the part of your tweaking that causes this? Probably not detail-7.

Frank

FelixGER
07-10-2011, 01:15 PM
I think my PP is not causing it. Even with PP off it looks like that.
But I just made screenshots of the scene and they donīt show aliasing. Iīm currently rendering a DVD to watch it on TV.

Hmm, canīt really see it on a standard PAL DVD.

Hereīs a screencap: http://www.imagebanana.com/view/0rfuriqj/AVCHD.jpg
No aliasing. Maybe a playback problem?

PDR
07-10-2011, 02:17 PM
I think my PP is not causing it. Even with PP off it looks like that.
But I just made screenshots of the scene and they donīt show aliasing. Iīm currently rendering a DVD to watch it on TV.

Hmm, canīt really see it on a standard PAL DVD.

Hereīs a screencap: http://www.imagebanana.com/view/0rfuriqj/AVCHD.jpg
No aliasing. Maybe a playback problem?


You cannot necessarily demonstrate it very well on DVD, because it's scaled down, so the artifacts are scaled down, and the spatial relationships are no longer the same

You cannot necessarily demonstrate it very well on a single frame, it's the frame to frame differences where the artfacts fluctuate that make it perceptible

It's definitely there in the original file, and if you played it back on blu-ray instead of DVD , you would see it. Still not as bad as a Canon DSLR

FelixGER
07-10-2011, 07:24 PM
Yep, but (sorry to say) A LOT worse than my good old GH2 which resolved more detail and NEVER aliased! While the FS100 is better on every other aspect, aliasing is a disapointment!
At least itīs only aliasing and not moire, which you would even see in the screenshot.

Rick Burnett
07-10-2011, 09:47 PM
Yep, but (sorry to say) A LOT worse than my good old GH2 which resolved more detail and NEVER aliased! While the FS100 is better on every other aspect, aliasing is a disapointment!
At least itīs only aliasing and not moire, which you would even see in the screenshot.

I just downloaded your MTS file and watching it with VLC on a MacBookPro and there is no aliasing on the roof, where I clearly saw it on your screen shot. This reminds me of the same incident that occurred back when someone was showing us footage shot of a street with a scooter and a bunch of shops. Sounds like there is some sort of issue with the files off of the FS100 and that path they take.

When I was playing around with the files from the other user, inside of Premiere Pro CS5, I got the same aliasing. Yet, again, when I played them back in VLC they were AWESOME looking. I think I would try doing some transcoding of those clips and see if we can figure out what is broken. Are you using Vegas? I think the other user was using Vegas as well that had the aliasing problems too. (Which is ironic, because it is a Sony product!)

The roof issues looked great, again, on my system.

Also, people might thing that the power lines are aliasing, but they are not, those are twisted lines. if they were, they'd move as you hand held the shot, but they don't, bumps stay in EXACT same spaces on the line when they move.

And if you want, I can easily post some really bad aliasing GH2 clips if you'd like to see :)

rejdmast
07-11-2011, 01:50 AM
Make sure you are watching it at 100% resolution and full quality. Any resizing on the computer display can cause aliasing.

FelixGER
07-11-2011, 05:25 AM
I just downloaded your MTS file and watching it with VLC on a MacBookPro and there is no aliasing on the roof, where I clearly saw it on your screen shot. This reminds me of the same incident that occurred back when someone was showing us footage shot of a street with a scooter and a bunch of shops. Sounds like there is some sort of issue with the files off of the FS100 and that path they take.

When I was playing around with the files from the other user, inside of Premiere Pro CS5, I got the same aliasing. Yet, again, when I played them back in VLC they were AWESOME looking. I think I would try doing some transcoding of those clips and see if we can figure out what is broken. Are you using Vegas? I think the other user was using Vegas as well that had the aliasing problems too. (Which is ironic, because it is a Sony product!)

The roof issues looked great, again, on my system.

Iīm playing it back on WMP, VLC and getting aliasing. I transcoded to cineform, tried some rendering. Always getting aliasing. Yep, Iīm using Vegas.
I remember this scooter clip. Also gave me aliasing on my system. Very weird!


Also, people might thing that the power lines are aliasing, but they are not, those are twisted lines. if they were, they'd move as you hand held the shot, but they don't, bumps stay in EXACT same spaces on the line when they move.

Thatīs absolutely correct.



And if you want, I can easily post some really bad aliasing GH2 clips if you'd like to see :)

That would be awesone!

dcloud
07-11-2011, 06:19 AM
Great post, rick.
Id say the aliasing you get from the AF or FS is something i would expect when shooting on a videocamera. its not hideous but subtle

FelixGER
07-11-2011, 06:44 AM
I just played the clip on my TV directly from my camera.
Looks like on my computer screen but the moment I hit pause the aliasing vanishes completely resolving every roof tile perfectly. So the info is there but not in the moving picture.

Duke M.
07-11-2011, 07:02 AM
Remember that aliasing results in false detail artifacts because the camera can't actually resolve at that frequency. In effect its added noise. In a single image that can look fine, but with multiple images the false detail is random and noticeable because it doesn't line up from frame to frame. Think along the lines of mosquito noise, which is another random artifact.

Every camera will alias at some frequency. When its at the ultra high frequencies its not very noticeable, Thankfully. The funny thing is its in such a narrow range that sometimes just a couple steps forward or back is enough to change the frequency and it disappears.

Rick Burnett
07-11-2011, 08:40 AM
I am looking at it 1:1 because I too am aware of what scaling can do. I watched full screen on my 1920x1200 screen (which is taller so it has black on top and bottom). Absolutely no aliasing in the played video at all in where I see it clearly in the screen grab Felix took. I have no doubt you are seeing it.

Do you have any friends with a Mac? I only ask that you go play the clip on VLC on the mac and see if you still see it. Maybe there is a codec installed on your system that is not playing well (and certain other people) and we need to track that down.

Just like that other clip, it's like NIGHT and DAY differences we are seeing. I watched the clip a dozen times in VLC on my machine to make sure I didn't see any issue and it was VERY crisp in that area where your shot is aliasing very badly. The good news to me is that once we figure this out, you can have the same crisp images that I see :)

maarek
07-11-2011, 06:18 PM
That file looked absolutely PERFECT to me with my VLC player. No aliasing anywhere at original size.

You guys know what the problem is? The problem is that some players deinterlace with bob when they believe the material is interlaced even when it's not. Windows Media Player does it so the material will look "aliased". VLC shows it exactly as it is (you do have to click deinterlace off or to weave). The same thing happens when you play it on your tv. TV's are still in the interlaced world and our Samsung LCD's at work also do bob-deinterlacing. When you press pause the tv shows the fields completely = good image.

There is no problem with that material. It looks perfect. Except for a tiny amount of aliasing on the leftmost buildings tiles. But not much.

Chris Johnston
07-11-2011, 08:48 PM
A is the AF100
B is the 7d
C is the FS100

+1

Rick Burnett
07-12-2011, 05:52 AM
+1

You did see that I've already released which is which?

A is FS100
B is AF100
C is 7D

:)

Douglas Villalba
07-12-2011, 07:39 AM
I can't see any alliasing on my MAC 27" LED. I see a little withe same converted file on my second monitor a 1440X900