colorspaces

Friday, June 03, 2005

Generic Colorspaces

200pxadditivecolormixing_1RGB uses additive color mixing, because it describes what kind of light needs to be emitted to produce a given color. Light is added together to create form from out of the darkness. RGB stores individual values for red, green and blue. RGBA is RGB with an additional channel, alpha, to indicate transparency.

Color spaces based on the RGB model include sRGB, Adobe RGB and Adobe Wide Gamut RGB.


200pxsubtractivecolormixing_2CMYK uses subtractive color mixing used in the printing process, because it describes what kind of inks need to be applied so the light reflected from them produces a given color. One starts with a white canvas, and uses ink to subtract color from white to create an image. CMYK stores ink values for cyan, magenta, yellow and black.

YIQ is used in NTSC (North American) television broadcasts for historical reasons. YIQ stores a luminance value with two chrominance values, corresponding approximately to the amounts of blue and red in the color. It corresponds closely to the YUV scheme used in PAL television except that the YIQ color space is rotated 33° with respect to the YUV color space. The YDbDr scheme used by SECAM television is rotated in another way. (work needed)

YPbPr is a scaled version of YUV. It is most commonly seen in its digital form, YCbCr, used widely in video and image compression schemes such as MPEG and JPEG.

HSV is often used by artists because it is often more natural to think about a color in terms of hue and saturation than in terms of additive or subtractive color components. HSV stores a hue value, a saturation value and an intensity value.

HLS is quite similar to HSV, with lightness replacing intensity value.