Arbortext IsoDraw creates colors based on the CMYK model which is also the process employed in the field of four-color printing. This model generates different colors by overprinting the four primary colors; cyan (C), magenta (M), yellow (Y), and black (K), in varying proportions. To allow the primary colors to be printed in separate printing runs, the color drawing must first be broken down into four individual color separations (one for each primary color). This process is known as color separation. Color mixes derived from the four primary colors which can later be split into individual process color separations are known as CMYK process colors.

You can also create your colors using the RGB color system. The RGB color system is used to depict colors on the screen. RGB colors are created by combining the three primary colors—red (R), green (G), and blue (B). Arbortext IsoDraw can convert a color created in the RGB color system to a CMYK process color or custom color.

You should use the RGB color system particularly when you want to use your color illustrations for online documentation. If you need high print quality, then it is essential to choose CMYK process colors.

In addition to creating colors with the CMYK model or using the RGB color system, Arbortext IsoDraw also allows you to define custom colors based on the CMYK model. Custom colors (also known as full-tone colors, special colors, spot colors, and real colors) are available as standardized, ready-mixed printing inks at the printers. They are used if, for example, the printed result contains fewer than four different colors. This reduces printing cost by reducing the number of color separations and printing runs. There are also some colors which cannot be produced effectively from the four process colors. A separate color separation is created for each custom color during the separation process.

Tone is another option for defining color in Arbortext IsoDraw. Tones are not colors in their own right but merely modifications of intensity (0-100%) of colors that have already been defined.

Because colors are depicted on the monitor using the RGB color system, the screen representation of the colors created using the CMYK model will usually vary somewhat from the subsequent printed result.

Arbortext IsoDraw supports color printers. Color separation is not possible directly in Arbortext IsoDraw; instead, you must export the drawing in EPS format and then integrate it into, for example, a layout program with separation functions, or output it with a special separation program.

You can still print out the drawing if you have used the RGB model for your colors. The colors are converted to CMYK colors by the printer. However, the printed colors are likely to differ from those in the screen representation.