XL2 image problem

Aaron Koolen · August 13th, 2004, 04:46 PM

Barry, that's absolutely freaky that you suggest those artifacts are normal. I would hae thought I'd have noticed stuff like that even on my lowly Xm2. Maybe not.

Cheers
Aaron

Barry Goyette · August 13th, 2004, 05:00 PM

Aaron

I'm not saying that they are absolutely normal for a video camera image (but all CCD's do produce exactly these types of artifacts)...

However, lets talk about your xm2...is it progressive scan...?...not really, it's frame mode, which as we all know uses a pixel shift strategy that effectively blurs the image slightly (25%) from what a progressive image off the same sensor would do. A better example would be to look at a highly detailed, patterned image off of the dvx100...I'll try to take a look in the next few days....

Regardless...remember this is a video camera...still frames don't mean much, and I'm doubtful that you would be able to see this kind of artifact on a TV....but I could be wrong.

Barry

John Mercer · August 13th, 2004, 05:05 PM

There seems to be something seriously wrong with this image compared to those PAL ones from the Simply DV review - they looked superb.

I suspect quite apart from the moire patterns there is something wrong in the way this image has been prepared as an exported jpg still - the resolution looks awful, not at all like the other stills and grabs I've seen so far.

Or if the still has been prepared/exported correctly then I would think there is definitely something wrong with the camera.

Clive Collier · August 13th, 2004, 05:16 PM

Hi Everyone and thanks for your comments.

First of all, yes the patterning is visible on playback both digitised and playing straight out of the camera straight into a video monitor. As I mentioned before, going through the frames on a TFT screen doesn't show the pattern as we are seeing the true progressive scan.

All these frame were taken from hand held moving footage without a tripod.

Suggesting using the auto mode to shoot is something worth trying although I certainly wouldn't expect to be forced to sacrifice making manual setting controls which in essence are at the heart of true detailed progressive work for DOP's.

I would have also thought that offering such potential to get such lovely sharp images as shown in my seagull shot would seem pointless if you have to downgrade sharpness or blurring the image just to rectify moire.

If the footage was viewed purely in progressive, then the effect would not be there if your workflow involved printing to film. However, I would suspect that most people would ideally like to maintain the look and feel for broadcast which does involve interlacing at some stage. If the implication is that such patterning would appear regardless of settings in the production final model, I think there could be issue. Perhaps the moire in the DVX100 is less pronounced due to its lower pixel res and lower spec lens which in a sense doesn't improve matters.

I certainly think that the camera is still a work in progress as Canon UK have pointed out that further revisions will be made based on our and other peoples findings.

Clive Collier · August 13th, 2004, 05:19 PM

Also, no artifacting was added turning the stills into JPEGs. What you see on the weblinks are identical to the actual raw frame data. Even the resizing in Photoshop doesn't detract as it remains faithful to the 16:9 view on our broadcast monitor.

John Mercer · August 13th, 2004, 05:20 PM

Clive,

Why is your still of such poor resolution when compared to those of the Simply DV UK PAL review?

http://www.simplydv.co.uk/Reviews/canon_xl2.html

It just doesn't look like we are seeing stills from the same camera.

Best regards,
John

Clive Collier · August 13th, 2004, 05:26 PM

Hi John

Take a look at these stills I put up earlier

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

The image of the gull looks much clearer than the images on the simplyDV site. In fact the long shot of the building towards the bottom of the review looks simply awful to me having used the camera. I think the image quality is superb with the exeption of this patterning.

Secondly, there is nothing in any of those shots which would cause a moire pattern. Where i saw the effect was on roof tiles, road markings and lines, contrast coloured bricks on walls and even front grills on cars

Barry Goyette · August 13th, 2004, 05:28 PM

I agree, John It would be nice to see an image that hasn't been expanded from the native DV frame. In addition to the moire, and ccd artifacts, some of what I'm seeing appears to be relative to bad upsampling, or interpolation.

Aaron...just did a little checking on the DVX...if I had to guess, I would say that the panasonic does have an AA filter. Some artifacts are visible, but not to the degree we see on the xl2 image (overall the image looks quite a bit softer on the DVX)...of course I'm comparing apples and watermelons here. On some gl2 footage, I saw exactly the same type of artifacts...although to a lesser degree...again I don't have any shots of brickwalls and railings in my files (mostly just naked girls and gun toting thugs!)

Clive--the long shot of the building on the simplydv site was shot on the XM2. I agree that your other shots look great, yet there is something out of whack on the brick wall shot...the micro pattern artifact doesn't match whats going on on your other shots...any thoughts?

Barry

Clive Collier · August 13th, 2004, 05:42 PM

Admittedly, the light conditions were less but flicking through shutter speeds, ND, iris and menusettings didn't have an impact at all.

The only slight possibility here is the act of creating the pseudo progressive scan. The DVX100 is only able to do this by buffering the signal which is the reason why on the initial release, some auto functions such as gain were disabled and the audio had a slight synching problem. If the XL2 is using the same technology or method (I think it is) then there could be some form of issue during the deinterlacing stage prior to dumping to tape.

Jeff Donald · August 13th, 2004, 05:43 PM

Clive, what exactly did you do to the image in PS? What lens were you using?

Clive Collier · August 13th, 2004, 05:47 PM

Changed image size from 720 to 1024 pixel width. Having said that, let me assure you that rather than get fixated on the images on the web page, the patterning is there on playback on a video monitor from footage captured via composite at 10bit uncompressed. The image quality is not the issue as shown in the other non-moire examples.

The lens was the standard Flourite x20 Canon lens as seen in the press photos. I have an Arri film lens coming tomorrow with an adaptor to try to eliminate the lens as a potential contributing factor.

Clive Collier · August 13th, 2004, 05:57 PM

Incidentally, we posted a message on the CML website asking for any questions which you would be interested in having answered in the review. Feel free to do the same here.

Showreel is a UK based magazine and the camera we have is a pre-production 25p model but many functions would remain the same. We go to press on tuesday so I'll make sure to check back before then to try and cover any particular issues.
(www.showreel.org)

Barry Goyette · August 13th, 2004, 05:59 PM

<<<-- the patterning is there on playback on a video monitor from footage captured via composite at 10bit uncompressed. >>>

just so we're clear...are you talking about the rather course moire which began the thread (circled area), or the pixel level artifacts that were discussed later.

barry

Clive Collier · August 13th, 2004, 06:00 PM

The moire.

Artifacting is not that noticeable unless dealing with harsh light which is pretty normal.

Gotta go guys. Its 1am!

Post any questions here or email me at clive@showreel.org

Thanks

Vamshidhar Kuchikulla · August 13th, 2004, 06:11 PM

to Barry:

Well barry. That depends on the image resolution in photoshop.I know if you take 640 vs 1280 picels, the ratio of the picels differs when zooming.

Alright.Although as per subject pal is 800000 picelled resolution. You have to imagine the quality. not even a dot should appear on the frame. To some extent i dont accept with your answer. I dont know weather i am correct or not .This moire effect may be when recording the ccd picels are not active or because of bit level or may be some adjustments in the settings of the camera. You come up with filters to use. In this regard this is not at all the solution. Let me tell you why , even if you record with filters, that effected picels may be darken. but the problem still persists. After all some people are making films with these cameras. May be if some one who has the xl2 pal version. Then we can know the proper reason, either camera defect or anything else.

may be i am not satisfactory to some people but i expressed what i think.

vamshi

August 13th, 2004, 04:46 PM	#16
Aaron Koolen Trustee Join Date: Apr 2002 Location: Auckland, New Zealand Posts: 1,727	Barry, that's absolutely freaky that you suggest those artifacts are normal. I would hae thought I'd have noticed stuff like that even on my lowly Xm2. Maybe not. Cheers Aaron __________________ My Website Meat Free Media

August 13th, 2004, 05:43 PM	#25
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	Clive, what exactly did you do to the image in PS? What lens were you using? __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

August 13th, 2004, 06:11 PM	#30
Vamshidhar Kuchikulla Regular Crew Join Date: Apr 2004 Location: ocho rios Posts: 45	hi to Barry: Well barry. That depends on the image resolution in photoshop.I know if you take 640 vs 1280 picels, the ratio of the picels differs when zooming. Alright.Although as per subject pal is 800000 picelled resolution. You have to imagine the quality. not even a dot should appear on the frame. To some extent i dont accept with your answer. I dont know weather i am correct or not .This moire effect may be when recording the ccd picels are not active or because of bit level or may be some adjustments in the settings of the camera. You come up with filters to use. In this regard this is not at all the solution. Let me tell you why , even if you record with filters, that effected picels may be darken. but the problem still persists. After all some people are making films with these cameras. May be if some one who has the xl2 pal version. Then we can know the proper reason, either camera defect or anything else. may be i am not satisfactory to some people but i expressed what i think. vamshi

August 13th, 2004, 05:00 PM	#17
Barry Goyette Trustee Join Date: Oct 2001 Location: San Luis Obispo CA Posts: 1,195	Aaron I'm not saying that they are absolutely normal for a video camera image (but all CCD's do produce exactly these types of artifacts)... However, lets talk about your xm2...is it progressive scan...?...not really, it's frame mode, which as we all know uses a pixel shift strategy that effectively blurs the image slightly (25%) from what a progressive image off the same sensor would do. A better example would be to look at a highly detailed, patterned image off of the dvx100...I'll try to take a look in the next few days.... Regardless...remember this is a video camera...still frames don't mean much, and I'm doubtful that you would be able to see this kind of artifact on a TV....but I could be wrong. Barry

August 13th, 2004, 05:05 PM	#18
John Mercer Regular Crew Join Date: Jul 2004 Location: Spain Posts: 73	There seems to be something seriously wrong with this image compared to those PAL ones from the Simply DV review - they looked superb. I suspect quite apart from the moire patterns there is something wrong in the way this image has been prepared as an exported jpg still - the resolution looks awful, not at all like the other stills and grabs I've seen so far. Or if the still has been prepared/exported correctly then I would think there is definitely something wrong with the camera.

August 13th, 2004, 05:16 PM	#19
Clive Collier New Boot Join Date: Aug 2004 Posts: 18	Hi Everyone and thanks for your comments. First of all, yes the patterning is visible on playback both digitised and playing straight out of the camera straight into a video monitor. As I mentioned before, going through the frames on a TFT screen doesn't show the pattern as we are seeing the true progressive scan. All these frame were taken from hand held moving footage without a tripod. Suggesting using the auto mode to shoot is something worth trying although I certainly wouldn't expect to be forced to sacrifice making manual setting controls which in essence are at the heart of true detailed progressive work for DOP's. I would have also thought that offering such potential to get such lovely sharp images as shown in my seagull shot would seem pointless if you have to downgrade sharpness or blurring the image just to rectify moire. If the footage was viewed purely in progressive, then the effect would not be there if your workflow involved printing to film. However, I would suspect that most people would ideally like to maintain the look and feel for broadcast which does involve interlacing at some stage. If the implication is that such patterning would appear regardless of settings in the production final model, I think there could be issue. Perhaps the moire in the DVX100 is less pronounced due to its lower pixel res and lower spec lens which in a sense doesn't improve matters. I certainly think that the camera is still a work in progress as Canon UK have pointed out that further revisions will be made based on our and other peoples findings.

August 13th, 2004, 05:19 PM	#20
Clive Collier New Boot Join Date: Aug 2004 Posts: 18	Also, no artifacting was added turning the stills into JPEGs. What you see on the weblinks are identical to the actual raw frame data. Even the resizing in Photoshop doesn't detract as it remains faithful to the 16:9 view on our broadcast monitor.

August 13th, 2004, 05:20 PM	#21
John Mercer Regular Crew Join Date: Jul 2004 Location: Spain Posts: 73	Clive, Why is your still of such poor resolution when compared to those of the Simply DV UK PAL review? http://www.simplydv.co.uk/Reviews/canon_xl2.html It just doesn't look like we are seeing stills from the same camera. Best regards, John

August 13th, 2004, 05:26 PM	#22
Clive Collier New Boot Join Date: Aug 2004 Posts: 18	Hi John Take a look at these stills I put up earlier http://www.showreel.org/XL2/xl2stills.html The image of the gull looks much clearer than the images on the simplyDV site. In fact the long shot of the building towards the bottom of the review looks simply awful to me having used the camera. I think the image quality is superb with the exeption of this patterning. Secondly, there is nothing in any of those shots which would cause a moire pattern. Where i saw the effect was on roof tiles, road markings and lines, contrast coloured bricks on walls and even front grills on cars

August 13th, 2004, 05:28 PM	#23
Barry Goyette Trustee Join Date: Oct 2001 Location: San Luis Obispo CA Posts: 1,195	I agree, John It would be nice to see an image that hasn't been expanded from the native DV frame. In addition to the moire, and ccd artifacts, some of what I'm seeing appears to be relative to bad upsampling, or interpolation. Aaron...just did a little checking on the DVX...if I had to guess, I would say that the panasonic does have an AA filter. Some artifacts are visible, but not to the degree we see on the xl2 image (overall the image looks quite a bit softer on the DVX)...of course I'm comparing apples and watermelons here. On some gl2 footage, I saw exactly the same type of artifacts...although to a lesser degree...again I don't have any shots of brickwalls and railings in my files (mostly just naked girls and gun toting thugs!) Clive--the long shot of the building on the simplydv site was shot on the XM2. I agree that your other shots look great, yet there is something out of whack on the brick wall shot...the micro pattern artifact doesn't match whats going on on your other shots...any thoughts? Barry

August 13th, 2004, 05:42 PM	#24
Clive Collier New Boot Join Date: Aug 2004 Posts: 18	Admittedly, the light conditions were less but flicking through shutter speeds, ND, iris and menusettings didn't have an impact at all. The only slight possibility here is the act of creating the pseudo progressive scan. The DVX100 is only able to do this by buffering the signal which is the reason why on the initial release, some auto functions such as gain were disabled and the audio had a slight synching problem. If the XL2 is using the same technology or method (I think it is) then there could be some form of issue during the deinterlacing stage prior to dumping to tape.

August 13th, 2004, 05:47 PM	#26
Clive Collier New Boot Join Date: Aug 2004 Posts: 18	Changed image size from 720 to 1024 pixel width. Having said that, let me assure you that rather than get fixated on the images on the web page, the patterning is there on playback on a video monitor from footage captured via composite at 10bit uncompressed. The image quality is not the issue as shown in the other non-moire examples. The lens was the standard Flourite x20 Canon lens as seen in the press photos. I have an Arri film lens coming tomorrow with an adaptor to try to eliminate the lens as a potential contributing factor.

August 13th, 2004, 05:57 PM	#27
Clive Collier New Boot Join Date: Aug 2004 Posts: 18	Incidentally, we posted a message on the CML website asking for any questions which you would be interested in having answered in the review. Feel free to do the same here. Showreel is a UK based magazine and the camera we have is a pre-production 25p model but many functions would remain the same. We go to press on tuesday so I'll make sure to check back before then to try and cover any particular issues. (www.showreel.org)

August 13th, 2004, 05:59 PM	#28
Barry Goyette Trustee Join Date: Oct 2001 Location: San Luis Obispo CA Posts: 1,195	<<<-- the patterning is there on playback on a video monitor from footage captured via composite at 10bit uncompressed. >>> just so we're clear...are you talking about the rather course moire which began the thread (circled area), or the pixel level artifacts that were discussed later. barry

August 13th, 2004, 06:00 PM	#29
Clive Collier New Boot Join Date: Aug 2004 Posts: 18	The moire. Artifacting is not that noticeable unless dealing with harsh light which is pretty normal. Gotta go guys. Its 1am! Post any questions here or email me at clive@showreel.org Thanks