The invention describes a system and method how tissue compression can be measured continuously in a non-contact way to provide a low cost, patient/user specific measurement system. The method may be used to inform existing and future pressure relief mattress systems. The invention may also be used for any application either in conjunction with another system or on its own to measure tissue compression. In another embodiment the invention can be used for measuring any type of compression of a compressible material, for example compression of viscoelastic foam or other materials. The invention may also be used to make inferences about the changes of blood flow at site of measurement.