Abstract: We exploit the correlations between 3D-stereoscopic left-right image pairs to achieve high compression factors for imageframe storage and image stream transmission. In particular, in image stream transmission, we can find extremely highcorrelations between left-right frames offset in time such that perspective-induced disparity between viewpoints and motion-induced parallax from a single viewpoint are nearly identical; we coin the term "WoridLine correlation' for this condition.We test these ideas in two implementations, (1) straightforward computing of blockwise cross- correlations, and (2)multiresolution hierarchical matching using a wavelet- based compression method. We find that good 3D-stereoscopic imagery can be had for only a few percent more storage space or transmission bandwidth than is required for the corresponding flat imagery.1. INTRODUCTIONThe successful development of compression schemes for motion video that exploit the high correlation between temporallyadjacent frames, e.g., MPEG, suggests that we might analogously exploit the high correlation between spatially or angularlyadjacent still frames, i.e., left-right 3D-stereoscopic image pairs. If left-right pairs are selected from 3D-stereoscopic motionstreams at different times, such that perspective-induced disparity left-right and motion-induced disparity earlier-laterproduce about the same visual effect, then extremely high correlation will exist between the members of these pairs. Thiseffect, for which we coin the term "WorldLine correlation", can be exploited to achieve extremely high compression factorsfor stereo video streams.Our experiments demonstrate that a reasonable synthesis of one image of a left-right stereo image pair can be estimated fromthe other uncompressed or conventionally compressed image augmented by a small set of numbers that describe the localcross-correlations in terms of a disparity map. When the set is as small (in bits) as 1 to 2% of the conventionally compressedimage the stereoscopically viewed pair consisting of one original and one synthesized image produces convincing stereoimagery. Occlusions, for which this approach of course fails, can be handled efficiently by encoding and transmitting errormaps (residuals) of regions where a local statistical operator indicates that an occlusion is probable.Two cross-correlation mapping schemes independently developed by two of us (P.G. and S.S.) have been coded and tested,