Improvements in or relating to electronic graphic systems

A greater degree of control over the painting of an image is provided in an electronic graphic system by arranging for features in an image being modified to be expanded or contracted under the control of the user. The expansion and contraction are both executed by offsetting image data and then writing the offset data to a store where it is combined by a weighted summation with data previously stored therein. This operation is repeated for different offsets. The effect of the weighted summation is also to add soft edges to features in the picture and the system may therefore be used to soften control images.