Edge-based dynamic ROI coding with standard compliance
An edge-based region-of-interest (ROI) image coding technique is proposed for low bit-rate visual communication. An image is compactly coded into two semantic levels: background sketch and object textures. The background sketch is a down-sampled version of the input image. The decoder reconstructs the background first by adaptive interpolation and lets users identify the ROI, and then requests the ROI textures to be transmitted. A distinct advantage of the proposed ROI technique is a compact edge-based descriptor of natural object boundaries. The expensive ROI geometry computations are carried out at the encoder only on demand, keeping decoder complexity low to benefit wireless devices. The new system outperforms the dynamic ROI coding of JPEG 2000 in both visuality and PSNR. Furthermore, both background and texture coding can be made compliant with any existing compression standard.