Complex sentence: Especially the "808" and the "1020" have very high resolution image sensors with on-chip image processors performing image scaling with oversampling giving lossless (optical) zoom.
Split into simpler sentences: Especially the "808" and the "1020" have very high resolution sensors with integrated oversampling technique. Their image sensors with on-chip image processor performing image scaling with oversampling gives lossless (optical) zoom.