HDV motion artifiacts

Alister Chapman · January 24th, 2006, 10:49 AM

The HDSDI output of the H1 is full 1920 resolution. The H1 CCD's are 1440x1080 BUT the camera uses pixel shift to get full frame resolution. Have not measured the actual resolution, but it is certainly higher over HDSDI than HDV. If you take a 1920 frame and downsample it to 1440 it certainly has a very similar look to an HDV frame. There is a cineform frame on the other thread that was created from the HDSDI stream, the 8 bit Cineform codec is only 1440x1080 and this frame has the same softer look. It should also be remembered that even HDCAM is downsampled to 1440 and I have yet to come across any domestic display that can actually resolve more than 1000 TVL. Most HD LCD's, Plasmas or CRT's can't resolve more than 700 TVL.
To my eye HDV is excellent, It is more than capable of pushing the limits of the playback/viewing equipment and artifacts really are not an issue in most situations. It's not perfect, but it is pretty damn good.

I think many of the issues people see are more down to the fact that it's an 8 bit codec and thus has only 256 grey levels, ie quantization and stair stepping on areas of nearly flat colour.

Don Donatello · January 24th, 2006, 10:05 PM

except for digibeta all SD tape formats are 8bit ...
all SD & HD tranmission/broadcast are 8bit ..
pretty much all HD is 8bit to tape except for the 24p camera's that are FILM camera types ( viper, panavision genisis, dalsa )
most 35mm film that is scanned to digital is 10bit files ( not 16, 24, 32) .. and then transferred back to film 10bit ...

it looks like we're stuck with 8 bit for awhile and i'm not seeing any sign of 10bit as a delivery format ( other then the transfer to film) ...

Wayne Morellini · January 24th, 2006, 10:45 PM

I have spent some time comparing that cineform HDSDi frame at magnification to the original and it has a little blur, but nowhere near that of the HDV one. I read, probably the Internet news compression FAQ, that the tables in Jpeg lack enough precision to be give a accurate result (in the lossless/jpeg section) so there precision is increased for lossless compression to the extent that the error will not effect pixel values. Maybe this is related to the problem?

So your saying it produces 1920 true res rather than 1440 upscaled to 1920, or 1440+pixel shift unprocessed upscaled. Interesting. I saw the original post on the Canon HDSDi, that talked about 1440 res, that's where I got the figure from, but I accept what you are saying, sorry Ken. It's hard to believe that they would get this right, but I'm happy that it turns out out be.

I'm curious, what ever happen to the plan to use the Z1/s CCD's in the Canon.

Alister Chapman · January 25th, 2006, 12:11 PM

BetaSP being analog dosn't suffer from many of the stair stepping and quantisation problems that most of the digital formats suffer from. However I would not for one moment want to go back to analog. Transcoding to 10 bit or higher for post production is getting easier and can improve the final image.

Canon do not quote the image resolution anywhere, simply that the CCD's have 1,560,000 pixels which is just over 1440x1080 and that pixel shift is employed which normally increases the resolution. Stills taken with the camera are grabbed at 1920x1080 so I think it is reasonable to assume that the camera head is operating at 1920x1080.

January 24th, 2006, 10:49 AM	#46
Alister Chapman Inner Circle Join Date: Dec 2005 Location: Bracknell, Berkshire, UK Posts: 4,957	The HDSDI output of the H1 is full 1920 resolution. The H1 CCD's are 1440x1080 BUT the camera uses pixel shift to get full frame resolution. Have not measured the actual resolution, but it is certainly higher over HDSDI than HDV. If you take a 1920 frame and downsample it to 1440 it certainly has a very similar look to an HDV frame. There is a cineform frame on the other thread that was created from the HDSDI stream, the 8 bit Cineform codec is only 1440x1080 and this frame has the same softer look. It should also be remembered that even HDCAM is downsampled to 1440 and I have yet to come across any domestic display that can actually resolve more than 1000 TVL. Most HD LCD's, Plasmas or CRT's can't resolve more than 700 TVL. To my eye HDV is excellent, It is more than capable of pushing the limits of the playback/viewing equipment and artifacts really are not an issue in most situations. It's not perfect, but it is pretty damn good. I think many of the issues people see are more down to the fact that it's an 8 bit codec and thus has only 256 grey levels, ie quantization and stair stepping on areas of nearly flat colour. __________________ Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com

January 25th, 2006, 12:11 PM	#49
Alister Chapman Inner Circle Join Date: Dec 2005 Location: Bracknell, Berkshire, UK Posts: 4,957	BetaSP being analog dosn't suffer from many of the stair stepping and quantisation problems that most of the digital formats suffer from. However I would not for one moment want to go back to analog. Transcoding to 10 bit or higher for post production is getting easier and can improve the final image. Canon do not quote the image resolution anywhere, simply that the CCD's have 1,560,000 pixels which is just over 1440x1080 and that pixel shift is employed which normally increases the resolution. Stills taken with the camera are grabbed at 1920x1080 so I think it is reasonable to assume that the camera head is operating at 1920x1080. __________________ Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com

January 24th, 2006, 10:05 PM	#47
Don Donatello Hawaiian Shirt Mogul Join Date: Nov 2001 Location: northern cailfornia Posts: 1,261	except for digibeta all SD tape formats are 8bit ... all SD & HD tranmission/broadcast are 8bit .. pretty much all HD is 8bit to tape except for the 24p camera's that are FILM camera types ( viper, panavision genisis, dalsa ) most 35mm film that is scanned to digital is 10bit files ( not 16, 24, 32) .. and then transferred back to film 10bit ... it looks like we're stuck with 8 bit for awhile and i'm not seeing any sign of 10bit as a delivery format ( other then the transfer to film) ...

January 24th, 2006, 10:45 PM	#48
Wayne Morellini Inner Circle Join Date: May 2003 Location: Australia Posts: 2,762	I have spent some time comparing that cineform HDSDi frame at magnification to the original and it has a little blur, but nowhere near that of the HDV one. I read, probably the Internet news compression FAQ, that the tables in Jpeg lack enough precision to be give a accurate result (in the lossless/jpeg section) so there precision is increased for lossless compression to the extent that the error will not effect pixel values. Maybe this is related to the problem? So your saying it produces 1920 true res rather than 1440 upscaled to 1920, or 1440+pixel shift unprocessed upscaled. Interesting. I saw the original post on the Canon HDSDi, that talked about 1440 res, that's where I got the figure from, but I accept what you are saying, sorry Ken. It's hard to believe that they would get this right, but I'm happy that it turns out out be. I'm curious, what ever happen to the plan to use the Z1/s CCD's in the Canon.