Be aware that HDMI supports two ways of encoding color. RGB (which is what PC monitors use) and YCbCr (which is the color space used by compressed video formats)
It is important that you understand this because video cards will sometimes choose a less than optimal color space format when hooked up to an HDTV. You can usually force the pixel format in your video card's driver settings. Explanation of YCbCr here
If you have to use YCbCr the use YCbCr 4:4:4 not YCbCr 4:2:2. 4:2:2 means that the color (CrBr) are half the resolution of the brightness (Y).
There will also (at least on ATI cards) be an option for "full range" and "studio range" when outputting RGB pixels
Full range means that brightness level RGB 0,0,0 = absolute black and RGB 255,255,255 = maximum white
Studio range means that absolute black = RGB 15,15,15 and maximum white = RGB 240,240,240
Ideally you want RGB full range. But you need to have your HDTV and your video card both set to use the same brightness range (i.e. full range or studio range). Most HDTV's will have an option for full range/studio range somewhere in the setup menus. (on Samsung TV's it is called "HDMI Black Level")
If you are using a DVI to HDMI cable then it will always be RGB full range.
Also, turn off *ALL*
"image enhancement" image sharpening, dynamic contrast etc. when using an HDTV as a PC monitor. It will just degrade the image quality. There will usually be an option in your HDTV's setup called something like "Movie" or "Natural" that disables most of this. Then it's just a matter of setting image sharpening to 0%, disabling "dynamic contrast" "edge enhancement" etc.
What you want is to display exactly the image that your PC is sending to the TV with no changes.
Tools you can use to adjust your brightness/gamma. Please note if you have any edge "enhancement" or image sharpening these will not work right. (but you should have all those turned off anyway)
Looks like I'm going to have to pull out my gamma correction/adjustment links again.
First of all, if you are using an LCD monitor set your desktop to the native resolution of your display.
Now we adjust your black point and white saturation level.
Black point test: http://www.drycreekphoto.com/Learn/Calibration/monitor_black.htm
White saturation test: http://www.lagom.nl/lcd-test/white.php
Another black point test: http://www.lagom.nl/lcd-test/black.php
Luminance sensitivity test: http://www.drycreekphoto.com/Learn/Calibration/monitor_sensitivity.html
Get your black point and white saturation correctly adjusted and then you need to adjust the gamma curve to 2.2 http://www.normankoren.com/makingfineprints1A.html#gammachart http://www.photoscientia.co.uk/2point2.htm http://www.graphics.cornell.edu/~westin/gamma/gamma.html http://www.lagom.nl/lcd-test/gamma_calibration.php
Do NOT use "Game Mode" (this looks like crap)
"Image enhancement" is really "image de
-enhancement" turn it all off.
Anything with the word "enhancement" or "dynamic" is garbage, for the love of God turn it off.
People that set their TV to "Vibrant" mode and then crank up the brightness to maximum make baby Jesus cry.
EDIT: There is currently a bug with ATI's drivers that cause the "full range" pixel format option to not work. (don't laugh Nvidia users your drivers don't even have
an option for full range) If you use a DVI to HDMI cable then this won't affect you (because DVI is always RGB full range)
EDIT: You want to set your HDTV to display the image with no overscan. On Samsung TV's this is under the "Size" option and is called "Just Scan". Most HDTVs will have an equivalent setting to this.
EDIT: You really shouldn't have to adjust your gamma curve if you have the black point and white saturation set correctly. A screwed up gamma curve is usually a sign that you have the white saturation (the maximum white) set too high and clipping is occurring)