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Old September 15th, 2007, 04:12 PM   #16
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Bill,
The color bars may not line up since the waveform monitor has its own settings for studio RGB versus computer RGB. The color bars will probably line up right if you set the WM appropriately.


Back to the main topic...
Some(/many/all?) filters will yield different results depending on whether you feed them studio RGB or computer RGB levels. So that might explain the differences in Grazie's JPEGs.
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Old September 16th, 2007, 02:51 AM   #17
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Quote:
Originally Posted by Glenn Chan View Post
Back to the main topic...
Some(/many/all?) filters will yield different results depending on whether you feed them studio RGB or computer RGB levels. So that might explain the differences in Grazie's JPEGs.
For the record, I used 32-bit 1.000 Linear working ON a 2 Link chain:

Link 1: CC - To achieve a better balance PLUS more contrast. Interesting, Glenn, 8bit gives me 95 on the Waveform (Luminance) Scope and 32bit gives me 98. Doesn't sound much, but at that high end it does quite a bit. PLUS 32bit removes a pink blush from everything too. This has to be the accuracy kicking in - yes?

Link 2: CCurves - To achieve a bit more warmth to the now CC-ed coldish look. The "reeds" which were pale-ish are now ruddier. But using the 32bit did NOT seriously affect the "green" watery look - which I wanted to retain.

I am still searching as to where I shall fit this in to my "creative" workflow and not get bogged down with low fps rates.

Best regards,

Grazie
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Old September 16th, 2007, 03:22 AM   #18
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Quote:
This has to be the accuracy kicking in - yes?
It's probably not the extra accuracy, but rather the filter being fed with computer RGB versus studio RGB levels.

There's different numbers going into the filter... so therefore different numbers come out.
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Old September 16th, 2007, 03:29 AM   #19
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Originally Posted by Glenn Chan View Post
It's probably not the extra accuracy, but rather the filter being fed with computer RGB versus studio RGB levels.
Where's that happening?

G
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Old September 16th, 2007, 04:02 AM   #20
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Flipping between 8-bit and 32-bit will change the behaviour of some codecs.
http://glennchan.info/articles/vegas...or/v8color.htm

HDV will decode to either studio RGB or computer RGB depending on the bit depth of your project.
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Old September 16th, 2007, 05:05 PM   #21
 
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Seems to me, then, that the vectorscope is currently inadequate for displaying the 32-bit float. Might I suggest a note that appears on the vectorscope that alerts the user as to which REC (601 vs 709) is being read/used, as well as a button to correct the readout. The vectorscope in DVRack/HDRack, reads out which color space is being used.
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Old September 17th, 2007, 01:03 PM   #22
 
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That's a good suggestion, Bill....having a small "601" or "709" appearing in the upper or lower corner...
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Old September 17th, 2007, 01:33 PM   #23
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It's always 601.

If you could flip between 601 and 709, the color bar targets would move (since the luma co-efficients are different). You can see this in FCP.

2- The difference between Rec. 601 and 709 is not the same as computer RGB versus studio RGB levels. It's two separate issues.

3- The settings for the scopes will affect its read-out.
7.5 IRE setup
computer RGB / studio RGB

There's no indication as to what the settings are.
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Old September 17th, 2007, 01:37 PM   #24
 
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Glenn..

Isn't it incorrect, and even useless, if the V8 vectorscope doesn't show REC709?
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Old September 17th, 2007, 07:27 PM   #25
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very confusing
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Old September 17th, 2007, 07:30 PM   #26
 
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It's really not that confusing. Had the two samples been posted with no discussion of color correction, or had the samples been generated with no color correction and simply an "8 bit display" and a "32bit display" it would make more sense.
What you *need* to know is this:
32 bit float modes will decode slightly differently than 8 bit mode with certain types of files. HDV, XDCAM, AVCHD benefit the most from this mode.
It "stretches" the gamma by nature of the additional bits. If you don't like this mode, then either stay in 8 bit mode, or use the 2.222 mode found in the 32 bit mode dialog in the Project Properties dialog.

It's really pretty simple overall.
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Old September 17th, 2007, 07:52 PM   #27
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Isn't it incorrect, and even useless, if the V8 vectorscope doesn't show REC709?
Yes and no? It depends on what you're using the scopes for.

2- Hmm my previous post may be wrong. It might be that Vegas' scopes behave as if they were monitoring a NTSC Y'UV signal. NTSC Y'UV is not the same as Rec. 601 Y'CbCr and not the same as Rec. 709 Y'CbCr.

2b- Basically the difference for the vectorscope is that the values and color bar targets move around.
http://www.dsclabs.com/images/244_VS_Web.jpg

The reason why everything shifts around is because all the numbers change.
The R'G'B' signal is converted into Y' B'-Y' R'-Y' and then into either Y'UV, Rec. 601 Y'CbCr, or Rec. 709 Y'CbCr.
The formulas are all different... you can look them up in Charles Poynton's book.

2c- The Vegas scopes can be misleading/"wrong" for various reasons. They do not behave like real hardware scopes and cannot do everything the hardware scopes can do. e.g. Hardware scopes can show the true levels for analog or SDI signals. Vegas' scopes can't do that.

3- The Vegas scopes behaviour can be somewhat useful in the following situation:

You pick chroma values off the scope and take note of their magnitude and angle. e.g. You can mouse over the scope and vegas will show you % and degree.
If you move between SD and HD resolution, the numbers will stay the same.

If Vegas had the FCP behaviour, the angle and magnitude would change depending if the project were SD or HD.

Last edited by Glenn Chan; September 17th, 2007 at 08:32 PM.
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Old September 17th, 2007, 08:32 PM   #28
 
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Indeed. I'm very confused about what the scopes show.
Nevertheless, Spot, let me be clear...I love the 32 bit mode. I'm just trying to understand what the technology is doing.

Last edited by Bill Ravens; September 18th, 2007 at 10:07 AM.
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Old September 17th, 2007, 08:36 PM   #29
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1- See my updated post.

2- The Vegas is somewhat like the following situation:

You took a composite SD, analog signal out of Vegas into a scope. This is what the Vegas scopes emulate. (Though there are differences, like what markings are on the scope and the terminology compared to a real vectorscope + waveform monitor.)
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Old September 18th, 2007, 08:38 AM   #30
 
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Quote:
Originally Posted by Douglas Spotted Eagle View Post
It's really not that confusing. Had the two samples been posted with no discussion of color correction, or had the samples been generated with no color correction and simply an "8 bit display" and a "32bit display" it would make more sense.
What you *need* to know is this:
32 bit float modes will decode slightly differently than 8 bit mode with certain types of files. HDV, XDCAM, AVCHD benefit the most from this mode.
It "stretches" the gamma by nature of the additional bits. If you don't like this mode, then either stay in 8 bit mode, or use the 2.222 mode found in the 32 bit mode dialog in the Project Properties dialog.

It's really pretty simple overall.
Graham, if you're still following this thread, would you do us a favor?

Would you, please, post the original images in their "raw" state, without any correction or changes, other than one in 8-bit and one in 32-bit using the 2.222 mode?

Thanks!
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