Bitmaps page 6 |
Resolution Additive Colour The RGB system (red, green, blue) is based on the concept of additive colour. The classic illustration of this system is of three overlapping disks:
This shows the effect of mixing the three primaries; every other visible colour can be achieved simply with different combinations of numbers. Subtractive colour Subtractive colour is not used in animation, but you need to know what it is so you can avoid it! Subtractive colour is the way of describing the effect of mixing pigments such as in ink or paint. You will know from experience that if you mix red and green paints, you will get something looking more like mud than the luminous yellow you do in additive colours. You will also know that you cannot mix three coloured inks or paints to create a pure black. Printers therefore use black itself as a fourth "primary". This system is known as CMYK. (Cyan, magenta, yellow, black). With inks of these four colours, a reasonable stab at reproducing natural colour can be made. If you want to know what cyan and magenta look like, by the way, they are the areas indicated as 0,255,255 and 255,0,255 respectively in the picture above. RGB and CMYK Most paint programs will work with RGB and CMYK files. If you are sent a picture for, say, colour references, you must ascertain that it is not CMYK. This is not likely to happen, but it will cause you grief if it does and remains undiscovered. Most paint programs will happily load either system without warning you. It is only at the very end of a job when you are doing a final output, that you may get to discover that you have used entirely wrong colours. To check whether a file is RGB or CMYK, use the option in your paint program to change the image mode. If the CMYK option is greyed out, that is a sure sign that the file is CMYK. You should then change it to RGB. That concludes the beginners' guide to bitmap graphics. To look at the notes on vector graphics, click here
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