Computer images of electron diffraction contrast from 90° wedge specimens containing strained III-V compound heterostructure layers are compared with experimental TEM images. The image contrast in the wedge is strongly affected by strain relaxation near the edge and allows unambiguous derivation of the bulk strain. The strain distributions used to simulate diffraction contrast are obtained by finite-element calculations. This new technique combines high spatial resolution with a high sensitivity (∼0.01%) for changes in the strain value. It also has the advantage of speed in the sample preparation.