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Canon XL and GL Series DV Camcorders
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Old August 13th, 2004, 12:46 PM   #1
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XL2 image problem

We have had the PAL 25p version of theXL2 for a few days testing for an indepth review in Showreel magazine (www.showreel.org) and have come across an issue which we were keen to see if possible to eliminate.

We have noticed that in 25p mode, there is a very pronouned morray pattern which we can't get rid of. It is visible in the viewfinder as well as in the final image on rooftops, brick walls and even road markings. Seems to become significantly less in 50i mode as you would might expect. We have given this feedback to Canon and have yet to have a response from Japan.

Does this appear in the US 24p and 30p modes?

We will be trying an Arri film lens to eliminate the standard Canon lens as a potential cause as we have yet to make custom or camera setting adjustments to get rid of it.

Any views or feedback would be appreciated.
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Old August 13th, 2004, 12:54 PM   #2
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Find it hard to believe that there would be problems already and it's not even officially released.
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Old August 13th, 2004, 01:13 PM   #3
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This isn't a joke I'm afraid.

Here are some shots to show clarity of image which is very impressive:

http://www.showreel.org/XL2/xl2stills.html

Will post morray pattern in a moment
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Old August 13th, 2004, 01:19 PM   #4
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hi clive

Nice to hear from you that you have XL2. Here in this region no one has NTSC version XL2 ,may be by the end of this month it may come out. People supporting canon is not revealing anything,only few of them are coming out. As I observed from this forum that the people who attended the East Expo, clearly explains that Canon Xl2 has not problems. While you are the first guy who revealed the camera. Can you please explain the morray pattern briefly.

I appreciate your post.

vamshi
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Old August 13th, 2004, 01:24 PM   #5
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I see what you mean. I also notice a bit of red bleeding or glow around the trees in the far bottom left of the image. This doesn't look good. As weird as this is I'd guess there is a defect in the unit or something. Something this obvious can't have slipped through could it? Here's the link just in case nobody can find it.

http://www.showreel.org/XL2/morray.html

Also....I see a pattern in the sign that looks bad! Is that in the real sign or is thatcaused by the pronlem you are reporting?
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Old August 13th, 2004, 01:27 PM   #6
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Here is the link to see what I'm saying

http://www.showreel.org/XL2/morray.html

First off, let me explain that this image is to show the patterning as seen on an interlaced monitor.

This could be a fields issue and easily explained. When you shoot in 25p and view on a TFT or CRT, of course, you are able to see the true prgressive scan of what has been filmed and the patterning doesn't appear as prominently. Regardless of this, both in the viewfinder during filming and when viewing on a video monitor or TV, this patterning becomes very evident. Changing field dominance doesn't change what you see on the video monitor. Indeed, setting your software to square pixels still shows this sort of patterning on an interlaced monitor as you would expect.

The question then remains that if this were to be used for broadcast, how would this patterning be rectified? We haven't yet had a chance to try all possibilities but at present, we haven't found a solution to eliminate it.
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Old August 13th, 2004, 01:33 PM   #7
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Something worth trying would be to change the detail setting....or whatever it would called on the new camera. I have seen similar happenings on my DVX100 in "thin" mode when I would film and the siding of my house got in the frame. The close horizontal lines would cause the frames to look jittery or flickery.

I don't know if that could be it but it does look really odd. Did you compress that "morray" image more? Cause compared to the seagull image it seems really grainy and pixelated. At least to my eye.
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Old August 13th, 2004, 01:47 PM   #8
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Visit http://www.showreel.org/XL2/morray.html again as I have put the progressive image on there too.

Difference is that the building was shot on a less sunny day.

We have tried many of the obvious settings. We've tried Vertical Detail, Sharpness, colour matrix, knee, black.. pretty much everything. Still the same effect which has given us the preclusion that it could either be a side effect of shooting on progressive or an issue with the lens.

As i mentioned, we have requested from Canon the exact settings needed to try and minimise this effect if possible. Currently, it appears that ourselves and the BBC are giving feedback which might be included in further revisions prior to product release. We're receiving a film lens tomorrow and will try that a a process of elimination.
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Old August 13th, 2004, 02:22 PM   #9
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Which program modes are you shooting in? I'm interested to see what the "Green Box" Full Auto mode produces, since it represents the camera's defaults and pretty much takes the shooter out of the equation.

You are working through and communicating with Canon UK, correct?

One possibility lies in the fact that you've received a pre-production market test (MT) sample for review. Could be that it's from one of the very first batches and is therefore perhaps 80% or 85% of its potential, and lacking any final tweaks. If there is in fact an issue here, the question would be whether or not it's been corrected for the mass production units which are all still at the factory in Japan.

Finally, have you been able to reproduce this Moire pattern effect by shooting different backgrounds which have a linear texture similar to the brick building in your frame grabs?
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Old August 13th, 2004, 04:28 PM   #10
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Are these samples from a static shot or panned? Not that either would justify this pattern but it might eliminate another variable i.e pan with long focal length etc.
Thank you.
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Old August 13th, 2004, 05:13 PM   #11
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What I'm seeing doesn't look out of line for any digital imaging device. As the frequency of photographed patterns approaches that of the CCD, it is typical to see these types of moire's. (unless the CCD has an anti-moire/aliasing filter). Your statement that the effect you are seeing is only visible (or more so) on a monitor and viewfinder...would indicate that this is really a product of the pattern frequency in relationship to the output device, not so much the camera...when I look at the strait 25p shot, I'm not seeing any appreciable moire in the area you circled.

The patterning in the red sign and railing is another thing. I think part of it is relative to macroblocking in the red (see adam wilt's article on the dvx100). Also it may be somewhat relative to the expansion of the image to 576x1024..it looks like classic stair stepping thats been interpolated.

One of the dreaded demons of progressive imaging is the detail level often causes problems with standard definition sets...as someone noted about the DVX. Moire's and twitter are part of the package. In the pro digital still camera world (backs without anti-moire filters), we learn to adjust our camera positions to avoid moire's that occur (of course we have the ability crop later).

Barry
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Old August 13th, 2004, 05:15 PM   #12
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If you look at the rest of the picture, both the heavy moire and light/no moire one you see all sorts of strange crosshatching and artifacts. It's everywhere - I assume this isn't just the JPG compression?

Now I see from the caption you say it's capture uncompressed. Are you capturing via video out or something, or are you really capturing firewire? While I thought this could be your problem you do mention that you can see this in the viewfinder which is scary.

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Old August 13th, 2004, 05:15 PM   #13
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Dang. I'm sure glad you're here, Barry! Thanks for the knowledgeable insight,
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Old August 13th, 2004, 05:24 PM   #14
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hi

Hi everybody.

Its not the capture problem. since according to clive the effect is showing in the viewfinder. It clearly expresses some serious internal problem.

vamshi
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Old August 13th, 2004, 05:35 PM   #15
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Aaron..

those smaller artifacts are also pretty typical of digital sensors, most of which get filtered out by the anti-aliasing filters on almost all digital cameras. When I got my Imacon Ixpress last year (instead of the Saab), which doesn't have one, I was quite shocked to see all the artifacts that my canon 10d covered up with its AA filter.

I think the critical question will be whether these artifacts show up in actual footage, not just still frames (they tend to move around)...my guess is that they will not be visible on an SD monitor, but I could be wrong.

Maybe someone knows whether AA filters are typically used on video cameras...and if so, whether canon has chosen not to put one on the xl2.
(why would you put an AA filter on a camera?--simply put.. AA filters blur the image slightly to eliminate patterning artifacts)

Varnshi--this type of moire would be extremely visible on a camera viewfinder, due to its relatively low resolution...here's a test--take the image, the strait 25p one that shows no moire, and open it in photoshop. Use the zoom tool to zoom out step by step. Notice how the moire in the brick area will appear and disappear as the image gets smaller(even though there is no noticeable moire in the full sized image.

Barry
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