What is YCbCr444?

I just brought home my first HD monitor, a ViewSonic VX2753mh, hooked it up, and began looking at the settings. Immediately, I noticed a very distinct "washed-out" feel to the colors. Googling around, I noticed that...although there were a lot of positive reviews about the monitor...there was a persistent complaint popping here and there:

"Washed out color,"

"Picture not crisp"

"...colors looked a little washed out and bland..."

None of this really made any sense to me, since the monitor was on display at the store, and looked perfectly fine--quite crisp, in fact.

After playing around with the monitor settings, I initially discovered an AV/PC toggle, and setting it to PC fixed the picture size (the entire desktop was now visible, before it had extended off the edges of the viewable area). It wasn't, however, until I found this setting, buried inside the nVidia Control Panel:

Digital Color Format: (RGB / YCbCr444)

It was set to RGB. Upon switching it to YCbCr444, immediately, the picture quality took a massive turn for the better. Colors are now vibrant, the blur is gone, and it is a sharp, crisp display, just as it was on display in the store.

Googling and Wikipedia both haven't turned up much in the way of information regarding this acronym, so I ask you:

What is YCbCr444, and why did choosing this setting make the monitor's colors and picture perfect? Shouldn't it be the default setting?

Solution 1:

This article describes it pretty well:

YCbCr is the YUV color space recorded digitally. Y is brightness (luma), and Cb and Cr are the U and V color difference signals (see YUV for details). In chroma subsampling, only the colors are compressed, not the luma because the eye is more sensitive to brightness than to the color components.

YCbCr is designated as 4:n:n. The 4 represents a sampling rate of 13.5 MHz, which is the standard frequency (ITU-R BT.601) for digitizing analog NTSC, PAL and SECAM. The next two digits represent the Cb and Cr rate. Review the illustrations below for details. Each 8x8 matrix represents a "macroblock" of 64 pixels in a video frame. The pink squares are the pixel locations where the sample is taken. Sony's HDCAM uses a different notation because it compresses both the luma and the colors (see 3:1:1).

4:4:4 (Cb/Cr Same as Luma) Cb and Cr are sampled at the same full rate as the luma. MPEG-2 supports 4:4:4 coding, but having the same number of color difference samples as the luma is considered overkill and not worth the additional bandwidth to transmit it. When video is converted from one color space to another, it is often resampled to 4:4:4 first.