Renders and Aliasing

MUTTLEY wrote on 2/25/2008, 3:21 PM

Got an arrow thats a PSD file thats getting all kinds of jacked up after rendering:



I've tried quite a few different colors and it happens on most and this red is much more muted then the one I started with. I've put Chroma Blur on and it helps some but not enough. It baffles me that it looks great BEFORE rendering but like crap after. Render settings are just NTSC DV Widescreen 24p (2-3 pulldown) with quality set to "Best". I've seen red's much more saturated than this on TV.

What's a guy gotta do ta get a decent lookin arrow?

- Ray
www.undergroundplanet.com

Comments

John_Cline wrote on 2/25/2008, 3:30 PM
This is a classic example of DV 4:1:1 color sampling. You have created a worst case example, a diagonal solid red on a solid background. If you need to go back to DV tape, there's nothing you can do about it. If your final product is DVD, then rendering directly from Vegas to 4:2:0 MPEG2 will minimize the problem.

John
rmack350 wrote on 2/25/2008, 4:17 PM
"What's a guy gotta do ta get a decent lookin arrow?"

Not render to DV, for one thing. DV throws out 75% of the color samples and then the decoder tries to calculate some average values in the empty spaces. It's a lousy system for hard edged graphics like that. It especially shows in diagonal red edges, but it's there in other diagonals as well.

Rob
johnmeyer wrote on 2/25/2008, 6:23 PM
There was a very good, quite long discussion about this about eighteen months or two years ago. The search engine is broken so don't bother trying to find it, but perhaps someone can provide a link. The answers already given correctly capture the essence of the problem, but the original thread provides lots of details, as well as suggestions as to what to do (i.e., if you don't render to DV, what else should you use).
fldave wrote on 2/25/2008, 7:46 PM
How big is the PSD file pixel-size wise?

Remember the tried and true "double the size" of your graphic, so a 720xAPR by 480 target means you should use a 1440xAPR by 960 graphic.

Not sure if that will help, but I always have great results with HDV stuff with very large titles/graphics. Then again, I am obviously not going to DV!

Worth a try!
DJPadre wrote on 2/25/2008, 8:46 PM
u know whats funny... throw the same graphic in premiere and use ur gfx card to output and it will use your gfx cards antialiasing tools to smooth the edge.

what your seeing, as i can tell from the stepping here, is that your also simulating the device aspect ratio

trick is to render the piece as square pixelk if you can, or better yet, turn the psd into a hdv 1280x720p sq AR and reimport... that is of course unless your running the arrow across a map or some such effect then ur screwed...

Its not just a colour space issue..
John_Cline wrote on 2/25/2008, 9:08 PM
I can't find the colorspace thread either, but here is a .ZIP file that contains some test images that I used to make my point:

www.johncline.com/colorspace.zip

It IS a DV 4:1:1 colorspace issue.

John
MUTTLEY wrote on 2/25/2008, 10:36 PM
Thanks all for the replys, I totally spaced on making the graphic bigger so thats one of my first things to do. Will try some of the various other suggestions and check out your zip John.

The white background isn't the actual background but it does look just as bad. Just tossed the white background in to make sure it was obvious.

And yea, the arrow is moving, not a map but you got the gist of it so looks like I am indeed screwed.

- Ray
www.undergroundplanet.com
johnmeyer wrote on 2/25/2008, 11:07 PM
I found one of the old threads on this subject:

Nasty artifacts with AVI render
GlennChan wrote on 2/25/2008, 11:29 PM
De-saturating the red and chroma blur will help a little bit.

Avoid the DV codec if you can (e.g. if going out to DVD).

2- If you have to go to DV, it will help very slightly to temporarily render the graphic with Microsoft's DV codec (which does things very differently than Vegas). You'll avoid the 1.5 pixel shift in the chroma that way (the chroma can get shifted 1.5 pixels to the left). But that may not be a huge deal.

The microsoft DV codec expects computer RGB color (which is probably what you generated the PSD for). If you are using Vegas' DV codec, you should likely apply a "computer RGB to studio RGB" color corrector preset on the file.

3- Check your results over firewire. Vegas makes DV material look worse than it will appear due to the way it decodes chroma.
DJPadre wrote on 2/25/2008, 11:51 PM
Like i said, Its not just a colour space issue..

Patryk Rebisz wrote on 2/26/2008, 2:52 AM
well, welcome to the wonderfull world of compressed video... the good news is that even on big productions they have to deal with unless they are shooting film or directly to 4:4:4.

I'm pretty sure i'm scared for life because i hate when there is red in the shot because of the issues u r running into.
fldave wrote on 2/26/2008, 9:02 AM
Ah ha, I use HuffYUV mostly, rarely use DV much anymore.
craftech wrote on 2/26/2008, 9:22 AM
Ah ha, I use HuffYUV mostly, rarely use DV much anymore.
============
Yes, and with giant hard drives dirt cheap these days I have been rendering uncompressed more and more and working from there. It's like a whole different world.

John
John_Cline wrote on 2/26/2008, 1:33 PM
I've kind of gotten away from HuffYUV lately, I can't find a version that will install into Vista. I've been using Lagarith instead.

John
Kennymusicman wrote on 2/26/2008, 1:50 PM
John - you still not got HuffYUV working?.. Thought you might have got it working for you since that thread went quiet.
John_Cline wrote on 2/26/2008, 1:56 PM
Well, I didn't really try that hard. Development of the HuffYUV codec has stopped, but Lagarith's development is still active. It is available in both x32 and x64 flavors and makes smaller files than HuffYUV.