Research is being carried out at TU Chemnitz into the determination of textile properties using image analysis. The set-up and operation of a laboratory test rig are described. Diffraction images of woven and knitted fabrics showing structural defects are reproduced. The computer software which has been developed is mentioned. The test rig (structural sensor) has been used to test woven, warp-and weft-knitted fabrics in the lower weight range of up to 160g/m².