HDMI Confusion: 24/30/48-bit sRGB YPbCbPrCr Super White xvYCC/color WHAT?

I’ve said it before: HDMI is confusing.

When configuring your PS3, for example, you’ll get several confusing options like “Super White” and “x.v. Color”, as well as choosing between “RGB” and “YPbPr / YCbCr”. What does all of this mean?

All of the above options have to do with color on your HDTV or monitor. Some people never notice any problems with color, and to some people, it can be pretty critical.

First, let’s start off with an easy one. RGB vs. YPbPr vs. YCbCr. RGB is what computer monitors speak: they have Red, Green, and Blue parts that are illuminated to show you colors on screen. YPbPr and YCbCr are analog and digital, respectively, color systems that separate information into brightness (Y), and then differences to derive the blue channel (Pb / Cb) and the red channel (Pr / Cr). It represents the intended color with a different system that has different properties: for instance, it can be more easily compressed. It can represent just about the same information.

Now, since HDMI is digital with an uncompressed video signal, it means a dedicated number of bits are allocated for each channel. For older systems, this is typically limited to 24 bits per pixel, giving you about 256 shades of red, green, and blue that can be mixed in RGB, for example. Newer systems support up to twice this color resolution, with 48 bits per pixel, with 65,536 shades of each component. This is often called Deep Color. Naturally, this will have better color than non-Deep Color models. But really, the difference between 24-bit and 48-bit color is pretty negligible for most people, and many HDTVs don’t even support more than 24-bit color anyways (some older models only support 18-bit color, with a mere 64 shades of each color &emdash; this is pretty noticeable to many people).

What is this “Super White”? The PS3 seems to support it, but doesn’t seem to define what it is, exactly, or how to tell if your HDTV supports it. What it really seems to do is to use a slightly better color space: the original YCbCr color specification was tailored for analog CRTs with an NTSC color model. In other words, they were old and had poor color, so the standard took advantage of this by not allowing colors that were impossible (like bright whites and dark blacks). HDTVs have a wider color gamut, so can use an enhanced color model. “Super White” seems to refer to using this slightly improved color model, which should give you some richer colors. Chances are, it does, so you should turn it on and see if it makes a difference for you.

Finally, there’s xvYCC / x.v.Color. These both refer to an even better color model that is capable of displaying nearly any color that humans can see (unlike the previously mentioned models, like NTSC’s, that do not support all colors). The term “x.v.Color” simply means that the product carrying that moniker will support the xvYCC color standard. This is, in general, a good thing, and is required of HDMI 1.3. Turn it on if your TV supports it.

I hope this clears up some of the confusion surrounding the crazy color terms floating around HDTVs these days.