The Problem

It's difficult to produce a successful colour scheme for a multi-coloured image.

In choosing colours for an interface, we must achieve a balance between several aesthetic and practical objectives, some associated with the interface as a whole, and some associated with individual interface components. The objectives are listed below in decreasing order of importance:

• expressing one's personal taste
• maintaining colour harmony within the interface
• achieving a pleasant overall appearance for the interface
• maintaining visual distinction between items on the screen
• achieving pleasant colours for individual interface components

Notice that of these five objectives, conventional colour pickers only help with the last, and least important objective. A few provide standardised colour schemes, which are fine if you work in a particular domain (your image comprises a background, a title, highlighted body text, subdued body text, and a few other standardised components), and if you're happy with the standard colour schemes.
    Less common are systems which take account of all the requirements listed above and ensure colour harmony in general. In fact, we haven't found any.