Color theory

Color theory is a complex study, and I present only a sampling here, to show how it is used in landscape design. For instance, according to color theory, the spectrum is often divided into 4 categories:
•Primary: reds, yellows and blues.
•Secondary: greens, violets (purples) and oranges.
•Tertiary: Mixtures of the primary and secondary categories.
•Neutral: White, grays and silvers.

Color theory and color wheel
When many people first start building their Web pages, they create pages in colors that they like. If you're lucky or have a good eye, you'll end up with colors that look nice together. But it's very easy to set up a color scheme that clashes and is difficult for your readers to view for long periods or at all.
Understanding color theory will help you to understand how color works on Web pages. And one of the first places to start learning color theory is with the color wheel. Sir Isaac Newton first put together a circular diagram of colors in 1666. This color wheel allows you to see groupings of colors that are harmonious together and other colors that might clash.

When I was in the local Bureau-En-Gros office here in Montreal, they were selling paper that you can put in your inkjet or bubblejet printer.

The special paper is used to print out an image that you can then copy onto a white t-shirt using nothing but a hot iron. If I recall correctly, they even had paper designed to do this transfer on a dark t-shirt.