1. A mask for producing an image feature on an image surface during a semiconductor fabrication process, the mask comprising: a main feature having opaque and transmissive areas arranged in the form of the image feature, each end of the main feature including at least one of an opaque edge and a transmissive edge; the opaque edge includes a set of transmissive assist features arranged therein such that the set of transmissive assist features align alternately with the transmissive areas of the main feature, and the transmissive edge includes a set of opaque assist features arranged therein such that the set of opaque assist features align alternately with the opaque areas of the main feature.