Pen and Brush objects define colours in terms of Red, Green and Blue components.

These are the primary colours for mixing lights and are different to the primary colours for paint.

You may find this table of Red, Green and Blue values useful to define colours of Pen and Brush objects. But we highly recommend experimenting with different settings on your own screen and printer for customised results.

Red 255:0:0   
Green 0:255:0
Blue 0:0:255   
Yellow 255:255:0  
Magenta 255:0:255
Cyan 0:255:255
Orange 255:128:0
Pink 255:128:128  
Brown 96:32:0  
Black 0:0:0  
White 255:255:255  
Dark Red 128:0:0  
Dark Green    0:128:0  
Dark Blue 0:0:128  

The Pen and Brush objects store colours with 24 bits (i.e. true colour). However if your screen is not a true colour screen the closest available colour will be chosen for each redraw.

Cadcorp SIS Desktop always uses a palette made up of a colour cube (216 = 6*6*6 colours) and many grey shades.

The colour cube ensures all colours can be approximated satisfactorily and true-colour bitmaps can be dithered quickly. The shades of grey ensure that grey bitmaps always look good.

If you are doing "head-up" digitising over aerial photographs on a 256-colour screen you should consider overriding the bitmap overlay’s colour to black. This will make the bitmap draw in shades of grey and the system palette will be optimised for this use.

Note: For details of the further colour options available when using Thematic Mapping see ColorBrewer.