YUY2 BTUYV YUV9 AND 12

[garryward]

okay I know what RGB is but has for these what the hell do they mean which is best? and what RGBA is there a list somewhere that will tell me

Cheers
Garry

[N0SoopForU]

Stick with YUY2 or RGB. Those are the most commonly used formats and I haven't found any use for the others.

RGBA is RGB with an ALPHA transparency layer.

<font size=-1>[ This Message was edited by: N0SoopForU on 2001-12-09 10:27:39 ]</font>

[KoalaBear]

Digital pictures -- still OR video -- are made up of a matrix of pixels. RGB represents the value of each pixel in terms of how much red, blue and green must be mixed together to represent that pixel's value (R+B+G = white).

YUV splits the pixel into two components: luma (Y) and chroma (U,V). Luma is the brightness of the pixel, or where it falls along the scale of black to white. Chroma is its color, represented as U (blue differential, B-Y) and V (red differential, R-Y) also known as YCbCr. The value of a pixel is thereby determined by its Y:U:V value, which is more or less[*] equivalent to RGB at 4:4:4.

The human eye is less sensitive to color than to brightness, so it's possible to sample colors at lower frequencies than luma without visible distortion, which is where pixel formats like 4:2:2 and 4:2:0 (representing chroma resolutions of 50% and 25% luma resolution, respectively) come into play.

YUV is obviously more compact than RGB, because 50% to 75% of the color information is thrown away, but the file sizes are still ungainly. This is why the HUFYUV codec is popular, because it applies Huffman (lossless) compression to the YUV pixel values, shrinking them still further without distorting them.

In summary then, YUV is a compact (and compressible) way to represent the value of each pixel that forms a picture. Capture cards and MPEG encoders handle this color format natively, so YUV can be considered a "better" format than RGB for these applications because no colorspace conversion is required. It is also the color format used by television itself, so regardless of the color space you start out with it will eventually be mapped to this color format anyway.

-------------[*] "more or less" does not mean "the same." Every color space (LAB, RGB, CMY, HSB, etc.) can reproduce a subset of the visible spectrum known as its gamut. Wherever the gamut between two color spaces overlap, you can translate colors between the two precisely.

[sommersby]

When ripping dvd's using dvd2avi I usually select rgb 24bit as the colors and overall picture is brighter than yuv which tends to dull everything slighty, I do use huffyuv when capturing with Vdub though.