Susumu Ichinose

Global brightness-variation compensation for video coding

A global brightness-variation compensation (GBC) scheme is proposed to improve the coding efficiency for video scenes that contain global brightness-variations caused by fade in/out, camera-iris adjustment, flicker, illumination change, and so on. In this scheme, a set of two brightness-variation parameters, which represent multiplier and offset components of the brightness-variation in the whole frame, is estimated. The brightness-variation is then compensated using the parameters. We also propose a method to apply the GBC scheme to component signals for video coding. Furthermore, a block-by-block on/off control method for GBC is introduced to improve the coding performance even for scenes including local variations in brightness caused by camera flashes, spotlights, and the like. Simulation results show that the proposed GBC scheme with the on/off control method improves the peak signal-to-noise ratio (PSNR) by 2-4 dB when the coded scenes contain brightness-variations.

Study on adaptive reference picture selection coding scheme for the NEWPRED-receiver-oriented mobile visual communication system

The NEWPRED method is effective in preventing the propagation of transmission errors in real-time video communication. Its performance depends on round-trip delay and the size of the reference picture memory. This paper presents a new method of reference picture selection that adapts to the conditions at the receiving side in a way that is controlled by that side.

Receiver-oriented real-time error resilient video communication system: adaptive recovery from error propagation in accordance with memory size at receiver

The NEWPRED method is a transmission error recovery technique for video communication. In the NEWPRED method, both the transmitting side and the receiving side store multiple reference pictures and select one of these to recover from an error. In general, the transmitting side has two methods of selecting a reference picture. One is ACK mode, in which the transmitting side makes its selection based on Ack signals sent from the receiving side, and the other is NACK mode, in which the selection is based on Nack signals sent from the receiving side. To reduce picture-quality degradation caused by errors, the transmitting side switches between these two modes by evaluating transmission error condition. However, when the reference picture memory size is small, the receiving side cannot decode the bitstream because it does not have the picture data indicated by the transmitting side. To solve this problem, we propose a new method of switching, in which the receiving side controls mode switching according to the size of the reference picture memory. We demonstrate its effectiveness in computer simulations.

Consideration on three-dimensional visual communication systems

A novel head-tracking technique for a full-color stereoscopic video display system is presented. Using this head-tracking system, the stereoscopic area is increased by a factor of three and stabilized stereoscopic images are observed. Two kinds of large-size rear-projection stereoscopic display systems that do not require special glasses are proposed. Experimental tests, confirming the effectiveness of the proposed systems, are described. By incorporating these techniques into visual communication systems, such as TV telephone systems, video conference systems, or virtual reality systems, a very natural and accurate depth sensation which cannot be obtained by conventional systems that require the viewer to wear special glasses may be possible. >