Pure White 255?

Movick wrote on 11/18/2009, 8:06 PM

I did some research and confirmed what I thought might be the problem I've been having rendering a pure white background in Vegas 5.0 as a true 255,255,255. As it turns out, video gamut is smaller than that of the pc (16-235 vs 0-255). Is there a way to force the background out of gamut to a true 255 with Vegas 5.0 using levels or any tricks? My current rendered white RGB value is 235,235,235.

Please help!!

Thanks in advance.

Mov

Comments

Laurence wrote on 11/18/2009, 8:16 PM

What you're seeing is the limitations built into whatever codec you are using. This would be the same regardless of which editor you tried since it is codec related. Since (judging by your other post) you are trying to match the white in a web page, maybe you could use a 235,235,235 white on your web page and match the background to the video instead of trying to match the video to the web page. That or do flash with a transparent alpha layer.

rmack350 wrote on 11/18/2009, 9:34 PM

I think it depends on what you're rendering to. For NTSC DV, for instance, you have to make a special effort not to get whites at 255,255,255.

Rob Mack

farss wrote on 11/18/2009, 10:58 PM

Using color curves and the waveform monitor to see what you're it is quite easy to push your legal whites (Y' = 235) to superwhites (Y '= 255).

If you're doing that then logically one would push the blacks down to superblacks at the same time. To do both in one hit use one of the FXs such as the Color Corrector and select Studio RGB to Computer RGB.

Bob.

Laurence wrote on 11/19/2009, 6:15 AM

I don't think he is having trouble getting a super white (255,255,255) out of Vegas. He is trying to get a super white that survives the render into a web playable codec.

farss wrote on 11/19/2009, 11:22 AM

" He is trying to get a super white that survives the render into a web playable codec."

If that's what he thinks his problem is then I doubt that's his problem.
I've yet to find a codec that does anything to vision levels. Feed it 255,255,255 and that's what you get. I havev't checked evry codec known to man of coarse but certainly most of the common ones.

What I suspect is happening is this. As he's quoting values in RGB he's probably taking a screenshot from a player and measuring that in Photoshop or similar. The correct way is to bring the encoded file back into Vegas and use the various scopes in it.
Reason I say this is if the player uses a video overlay then what ends up on the screen is not what's in the encoded file. How it ends up depends on settings in the video cards controls, it can de-interlace, adjust levels and use ICM Profiles.

Bob.

GlennChan wrote on 11/19/2009, 8:08 PM

1- You'll get very confused if you don't pay attention to the units.

It's like talking about temperature without saying whether you're talking about Fahrenheit or Celsius. Water freezes at 0... or maybe at 32.

When it comes to levels, there are different types of "units" / ways of storing image values
0-255 RGB
16-235 RGB (legal info stored in 16-235; 0-15 and 236-255 reserved for headroom / illegal values)
16-235 Y'CbCr
*Don't worry about 0-255 Y'CbCr, it exists internally in JPEG but you almost never have to worry about it.

Vegas never deals with 16-235 Y'CbCr directly- it can only do so through interfaces to codecs, which is RGB. So the way I look at it is this:
- There is only one correct way of encoding your master.
- Your codec will either want to see (expects) 0-255 RGB levels or 16-235 RGB levels.
see
http://www.glennchan.info/articles/vegas/v8color/vegas-9-levels.htm

---------------
2- Vegas' scopes may be more confusing than helpful. It's a bit of a catch 22... you need to know what's going on for them to be helpful, but they're not helpful if you don't know what's going on. If you don't know what's happening, then you can't set them correctly; the scopes show different things depending on the settings.

3- What are you rendering to?
What codec and/or program is playing it back?

Vegas 5.0
Yikes, that is old! Some of the information on my site may not apply to Vegas 5... many things have changed in regards to how Vegas handles levels.
Things are different in the newer versions.

-----------------------------------
Check that there isn't anything in your Video Preview or Track FX.
One way to check is to disable FX completely by clicking the half-moon icon in the Video Preview window (look in its drop-down for options). There are other ways to check, e.g. looking into the FX chains.

farss wrote on 11/19/2009, 11:51 PM

I seriously doubt the problem here has anything to do with what you're saying, unfortunately. I say this because thinking back I've been caught out by exactly the same problem.
The problem lies in the player. Some use the video overlay and most video cards let you calibrate that independantly of the rest of the desktop. What then happens is this. You put Vegas's gen media white onto the T/L and it looks the same as white anywhere else on the screen. You encode that R'G'B' = 255,255,255 white and play the file back and it's grey. You take the file back into Vegas and check it on the scopes and compare it to the original and it is exactly the same???? What the scopes read and units of measurement are irrelevant, two identical whites should look identical regardless but they don't.

The problem is the player is using a different video pipeline with its own LUTs and gamma adjustment. I'd forgotten I'd played around with mine, it didn't seem to do anything so I'd just left it in some way out of wack state. Resetting it to the defaults and sanity was restored.

Bob.