Setting, Gamma, & color for Hi Def LCD, HDMI

[John L. Miller]

Ok, I have tried to set my 26" sanyo widescreen LCD hi Def TV color for video editing. I do not shoot in Hi Def, nor edit in Hi Def, but I have my Nvidia video Card HDMI out going to the input HDMI on the TV. I set the Video card for 720P Hi Def out. I did this because that is what the TV is. The picture is awesome, except that I know the color isn't set right. So I used Vegas Pluge bars to set the blacks. At least I tried to, then I found that turning the contrast all the way up and brightness all the way down still wouldn't get the two blacks to blend on the bars. So I tweaked on the Nvidia Gamma setting for the card and I was able to get the blacks correct...at least it blends perfectly...but then when I started to edit, it looks too high in contrast and way too dark. I feel if I were setting the settings on a regular TV it would have been fine, but is there a different procedure in setting an LCD hi def? Or, can someone tell me the correct GAMMA setting on my video card out for a Hi Def LCD TV. I feel that once I find the right gamma, I can truly get the colors right. At this point, I have had to turn up the brightness. Any help is always much appreciated. J

[Glenn Chan]

The color bars in Vegas are useful only if you are going video out over firewire or SDI, and if you are using the default DV or SDI (SonyYUV) codec.

If you keep your video card settings in their default/neutral position, and the same for your HDMI TV, then your system (the interface at least) will likely be calibrated. Digital connections don't need calibration.

You could tweak black level on your monitor to compensate for glare... although that's a subjective adjustment.

[John L. Miller]

I thought the digital connection should give me the correct colors, but the pluge bars in vegas are not matching blacks when card and tv are at default. I can't even make them match adjusting the tv alone, I have to tweak gamma on card to make them match then everything else is off. Thanks. j

[Glenn Chan]

In the computer world, black level is typically at 0.
In the video world, black level is typically at 16 (Y' at 16 for 8-bit Y'CbCr signals).

In Vegas, the color bars have black level at 16 16 16 R'G'B' since the default codecs will convert that to Y'=16 when going firewire or SDI out.

So if the bars don't work on your computer monitor, that is why.

2- What you could be doing is this:
Use the computer monitor (your TV connected to your video card essentially acts as a computer monitor) as your Vegas secondary preview device.

Under the preferences for external video, make sure color management and "use studio RGB (16-235)" are both checked. This will convert from 16-235 range (video range, or "studio RGB") to computer RGB range (0-255) for the preview device. This just affects preview, it doesn't affect your render.

If you do that, you should make sure that your video and other input decodes to studio RGB levels. If you use the default codecs, any DV and HDV and other video formats will decode to studio RGB levels. Computer formats like stills, JPEG, GIF, and most quicktime codecs will decode to 0-255 computer RGB range. Convert the latter into studio RGB levels with the "computer RGB to studio RGB" preset in the color corrector.

[John L. Miller]

Thanks Glen, great information that I will immediately put to use. J