Spatial filtering, spectral matched inhibition, and recovering of defo
cused images are implemented by modulation of the induced birefringenc
e of a BSO crystal. The intensity distribution received by the crystal
modulates the induced birefringence and the ellipticity of the transm
itted light is then modified as it propagates through the crystal. To
describe the processor, a 4-f optical system is used. A simple physica
l model is introduced and numerical and experimental results are prese
nted.