I am currently working on my thesis and I would like to ask you: does anybody know the mathematical formula that calculates the color gradient in Arcgis and Qgis? In other words, which mathematical equation is used to represent the color transition from one color to another in a buffer? And also: is there a different equation that calculates the color classification in other shapes, such as square, circle etc? A good example can be found in How to Calculate Color Gradient (www.ehow.com), but this is rather general. I would prefer something that concerns Qgis and Arcgis.
EDIT: 20/01/2013

The arrow doesn't mean anything...