[Keith Slawinski]

Thank you Tim and Jeff for your robust technical knowledge. It will save me lots of tinkering time.
If I may, I ran a few more tests and would like to reiterate what I have read and make sure I know what to do. The client says that Luminance and Chrominance need to be within NTSC SD broadcast safe upon delivery via digital file type.

1. If exporting to a file, DVD, or other digital media that will be sent to broadcast aim to keep the IRE on the Premiere waveform between 0 and 100. This is the best way to prepare for SD NTSC broadcast without affording 3rd party software or downstream hardware monitors. You can turn on setup7.5 IRE checkbox if your used to looking at analog signals, but manually setting levels to 7.5 is redundant (as the toggled on setup7.5 checkbox will show you your baseline IRE would really be closer to 15 analog IRE)

2. “Broadcast color” effect is not the end all solution to ensure a proper color space and “levels” seems to be a better choice.
QUESTION: levels effect seems to do the same thing to luminance when applied. It limits all IRE values over 100 to 100 immediately. Do you use levels because it applies this “limit” to luminance without effecting chromatic levels?

3. Try to keep all colors on the vectorscope within the target range whenever possible for broadcast (IE the closer box).

CASE STUDY: “levels” and “luma curves”.
The following test was done with footage that ranged from 7.5 IRE to 110 IRE (note the setup7.5IRE toggle is not on and black should be 0 IRE). In this footage, an interior close-up of a subject is near a visible window with exterior light blowing out the background.

“Levels” limits the waveform to 100 IRE. We do not see this change because the computers RGB color space cannot display color over 100IRE and the trimmed data is not usually missed. But what if we apply a Luma curve adjustment below the levels to play with contrast or brightness after the fact? The data above 100 IRE is lost and if we adjust the Luma curve we will be forever absent of the data. White areas will stay white, and if the brightness is lowered those whites are quickly replaced with matte grays.

I then switched the order of the effects. With the luma curve I maintained the mid-tones while adjusting the shadows and highlights till they were contained between 0-100 IRE. The levels adjustment layer was applied below to ensure there were no peaks over 100 IRE. This produced a very rich image that retained varying values outside the window previously crushed by the levels effect.
Placing the two instances side by side, the image with “levels” applied on top had more hot spots and less exterior detail.

There is a good chance this is common knowledge to you both, and levels is only applied at the final stage of the process for safety anyways, but for others viewing this thread, and trying to learn how to push image quality, this may be useful (especially if the average video is pushing 110 IRE).

I hope I am right about all this. If not, please feel free to correct my deductions.

LASTY: sorry this is so long, but in case I would like to learn more about HDTV standards or rec 706 colorspace, where would be a good place to look?

Thanks
Keith