Blend control system

The present invention provides a method and apparatus for determining color blend of a computer graphical object (4). The method involves providing a plurality of interactive control points (5,6), each of the control points (5,6) having an associated color value; and calculating a color value of each portion of the object depending on its relative position to the control points. Preferably, the number of the control points (5,6) is two. Preferably, the position or associated color value of each of the control points (5,6) can be interactively altered and the method further comprises the step of recalculating the color values of each portion of the object (4) when the control points are altered. Preferably, the portions of the object (4) having a projection outside a line taken between the two control points are determined to have a color substantially the same as the closest one of the control points (5,6).