THIS DEAL OF HELP IS DEDICATED TO SKILLED USERS OF GRAPHICAL PROGRAMS
In this part can you find further informations about some terms mentioned in this help. It's not necessary for most users...
RGB - is colorpace model, which is used in most graphical programs and it's basic model because of it's monitor-displaying simplicity (which are using Red, Green and Blue channels). Color in this model contains three channels - Red, Green and Blue. Each channel is representing intensity of that color (floating point number, 0 is zero intensity, 1 is maximum; on computers is used 0-255 range - for memory saving is integer used). UniView uses RGB with range 0-255, because of it's speed...
CMYK - colorspace used on printers. It contains Cyan, Magenta, Yellow and blacK channels. There is also a CMY colorspace available, but using CMYK, printer can save much printer ink (or toner etc.) because it doesn't have to use combination of CMY to produce black color - it directly uses black... If you want to compute valueas of CMY channels depending on RGB (0-255), use following table. If you use CMYK, it's not so simple and there are more complex algorithms used.
| R= | 255-C |
| G= | 255-M |
| B= | 255-Y |
| ----- | ----- |
| C= | 255-R |
| M= | 255-G |
| Y= | 255-B |
PS: As I already noted, CMYK colorspace is used by printing. You should know that RGB to CMYK conversion process is lossy - some colors (near to red, green and blue) are discarded because of printing technology limitations. Eg. following picture shows, how cyan, magenta and yellow colors have to mix. In real, it isn't so...
HSV, HSL, HSB - all these colorspaces was developed to make color specification more readable for human - HSV (Hue Saturation Value), HSB (Hue Saturation Brightness), a HLS (Hue Lightness Saturation). As an example take we HLS. As you saw, it contains three color specificators. Hue is describing color tone and it's unit is degree - so it can be 0░-360░ (An the picture can you see order of color tones by L and S at 50 - see next sentence). Lightness and Saturation are values in range 0-100. If Lightness is 0, color is black, if it's 100, color is white. If Saturation is 0, color is greyscale, if it's 100, color is at maximum intensity.
![Color palette for H=[0, 360]](/file/23408/Chip_2002-02_cd1.bin/ctenari/Krutak/univiewi.exe/uniview.chm/colorspace2.png)
YUV, YCbCr, YPbPr, CIE xyz, L*a*b* - These and other colorspace formats were developed for use in TV receivers (especially color TV's) and computer animations (MPEG, DVD etc.)
If you want to know something more about this theme, very good source if informations are discussion forum's (comp.graphics, comp.graphics.algorithms) or misc. internet pages (
http://www.inforamp.net/~poynton/Poynton-color.html). You can also use some good internet search service with keywords like: : colorspace, color encoding, YUV, RGB and so on.
