Help: Artifacts on edges of stills

hugoharris wrote on 6/6/2003, 8:50 PM
I'm experiencing a problem with a thin light-coloured line showing up on the edges of JPEG and PNG stills projected against a black background. I've tried adjusting all the still properties available (interlacing, pixel aspects, etc.) without luck. I know the line is not present on the image, because cropping the image does not change the artifact, and it is not present when viewed in Photoshop. The artifact is seen on the timeline preview, as well as when rendered to MPEG or AVI files. It is present when viewed on both my NTSC external monitor and the computer monitor.

I've tried to find an answer in the forum and in the manual without luck. Any help would be appreciated. The project is about 6MB, so I could e-mail it out (or produce a screenshot and e-mail it) if this might help.

Thanks,
Kevin.

Comments

farss wrote on 6/6/2003, 9:25 PM
I have had exactly the same problem, a single pixel wide white line on the RH edge of the still. It didn't show up on all the stills either but couldn't find a common thread to why it was happening. To really confude things we got the same results bringing them into FCP so I can safely say its not a VV issue!

If its really causing you grief you could just add a really thin mask on an upper track to block out the line.

There is an issue with alpha channels in general, only png use more than 1 bit of aplha channel and this can cause artifacts to appear, maybe you could try croppin them every so slightly in Photoshop and the save them as pngs. I'll also advise you to watch bringing large stills into VV or any NLE from what I have learnt, things start to get VERY slow!

If you're not doing any pan or crop in VV convert them to DV resolution elsewhere and save them as pngs. I did a quick a/b test and there is no difference in final quality.
johnmeyer wrote on 6/6/2003, 11:34 PM
I believe that I have read in other threads that when rendering stills, you get better results by going to the Custom button in the render dialog and selecting Best instead of Good for rendering quality. Try that on a short segment and see if it helps.
hugoharris wrote on 6/7/2003, 12:06 AM
Thanks for the suggestions. I'll try them tomorrow and report back.

Kevin.
hugoharris wrote on 6/7/2003, 4:05 PM
I tried to render with "best" instead of "good" quality, and it resulted in a small improvement. The artifact was still very noticable.

I then created a mask (a 1 or 2 pixel wide black strip) to apply to the edge of the still; this worked very well in general but with one still the white line at the edge simply moved to the interior edge of the mask!

Thanks for your help. I'll play with the images themselves over the next few days and report back if I find a combination that seems to work well.

Kevin.
hugoharris wrote on 6/9/2003, 1:16 PM
One final post...

I played around with image sizes, settings, types, and rendering quality over the weekend. Using "best" rendering quality makes a big difference, but the linear artifact is present on the right edge (and sometimes bottom) of some images...I can't seem to predict which ones will display this anomaly based on the image themselves. The artifacting appears to show up more after track motion changes. I placed a 5, 10, and 20 pixel wide black border around the images, but this did not affect the artifact (it would show up even more clearly adjacent to the border). In the end, I applied a 2 pixel wide mask immediately after the track motion to cover the artifacts.

Kevin.
SonyDennis wrote on 6/11/2003, 11:01 PM
What are the media properties for these stills? Are they 8 bits per pixel?
///d@
hugoharris wrote on 6/12/2003, 12:12 AM
The original stills are ~3 megapixel jpeg images taken with a Canon digital camera; they are 8 bits per RGB channel - 24 bits/pixel, imported into Photoshop 6.0 and edited there before being used in Vegas. Both the originals and edited versions display the same behaviour. I've tried changing the stills in the following ways without success:
- I've resized the images to lower resolutions.
- I've introduced a black border to match the background the stills are placed on.
- I've converted the stills to 16 bit/channel files.
- I've converted the files to .png, .psd, and .tif formats.

By the way, I'm new to Vegas, and I just wanted to comment on the amazing support from both Sonic Foundry and the user community. Simply put, I'm hooked. The software is extremely stable, and amazingly intuitive (even for an audio guy like me!). I use Cubase SX for audio intensive work, and if you want to see how the other side lives, visit the forums on Cubase.net.

Thanks,
Kevin.
SonyEPM wrote on 6/16/2003, 8:30 AM
Hugoharris- please send a .veg project file, a couple of example stills, and your render settings to drdropout@sonicfoundry.com - we'll take a look.
hugoharris wrote on 6/17/2003, 9:34 PM
A follow-up post:

SoFo's suggested work-around is a lot more elegant than mine; just tweak the glow settings using a small size and a colour to match the background (black, in my case). Thanks Dave and SoFo!

Kevin.
SonyDennis wrote on 6/20/2003, 4:59 PM
Actually, you don't need to change the glow color, just the alpha (opacity) of the color. That will work over any background, not just black.
///d@
hugoharris wrote on 6/20/2003, 5:57 PM
Ah, I see. Thanks (again).

Kevin.