Help please. Key based on luminosity?

NickHope wrote on 8/29/2005, 9:20 AM
How can I make parts of an event translucent depending on their luminosity?

I have some experience with compositing including chroma keying, color passing, secondary color corrector using masking etc. but I just can't get this. Been trying for hours and I'm ripping my hair out.

I can make a black and white mask based on luminosity using the mask generator, and I can make the track underneath show through it, but the rest of it remains black or white and I need it to be the original colour.

Comments

NickHope wrote on 8/29/2005, 10:12 AM
Thanks for the suggestion Marquat. I've got it working somewhat with the chroma-keyer filter but the smoothing is poor because I'm trying to mask based on subtle differences in luminosity, not colour and so the end result is not good.

I've closely followed the exercise on page 254 of the Sony Vegas 6 manual, which should do what I want. But my skier refuses to take on the colour of the track beneath him no matter what compositing modes I try on the various tracks. He just stays black or white.

Can anyone suggest what I might be doing wrong? What should the compositing modes of the tracks be set to in that exercise?

Thanks. I'd be hugely grateful to get this working.
briggs wrote on 8/29/2005, 10:37 AM
I always go back to this thread when trying to figure out masking.

http://www.sonymediasoftware.com/forums/ShowMessage.asp?ForumID=4&MessageID=305276

See PeterWright and DGrob posts about luminosity settings.

-Les
briggs wrote on 8/29/2005, 11:00 AM
Also, here's a sample veggie that uses gradient levels of luminosity as a mask. A little different approach, but maybe it will help.

http://www.vasst.com/resource.aspx?id=6a527eaf-afca-4119-bb69-3e2f54ea8e0c

-Les
chayman wrote on 8/29/2005, 11:10 AM
When you say "parts of the event", Do you mean time-wise or space-wise on the frame? If you mean time-wise, add in a "composite level" video envelope. Use it just like an audio envelope taking the upper level video in and out at whatever level you wish.
NickHope wrote on 8/29/2005, 11:17 AM
Les, thank you very much indeed, that thread sorted me out. My girlfriend would also like to thank you very much as she has had to spend the last few hours listening to me swearing. We both wish those awfully nice people at Sony had rewritten page 254 of their manual after version 4. I'm sure I will not be the last...

Nick