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.

We clarify the relationship between motion vectors (two parameters) and all camera motion, namely scaling, rotation and translation. All camera motions are described as Hermart transform coefficients. After all scaling and rotation factors of camera motion are removed, translation factors represent the depth of real three dimensional world. So we proposed a new sprite model, which is consist of planes vertical towards the depth direction. Using this sprite model, any background reflecting any camera motion creates sprites. Our simulation results show clear sprites and a clear synthesized image. The correlation between the original image and the synthesized image is more than 0.7. That indicates that the created sprites are suitable for prediction.

This paper describes a high-efficiency video coding method based on ITU-T H.263. To improve the coding efficiency of H.263, a two-stage motion compensation (MC) method is proposed, consisting of global MC (GMC) for predicting camera motion and local MC (LMC) for macroblock prediction. First, global motion such as panning, tilting, and zooming is estimated, and the global-motion-compensated image is produced for use as a reference in LMC. Next, LMC is performed both for the global-motion-compensated reference image and for the image without GMC. LMC employs an affine motion model in the context of H.263's overlapped block motion compensation. Using the overlapped block affine MC, rotation and scaling of small objects can be predicted, in addition to translational motion. In the proposed method, GMC is adaptively turned on/off for each macroblock since GMC cannot be used for prediction in all regions in a frame. In addition, either an affine or a translational motion model is adaptively selected in LMC for each macroblock. Simulation results show that the proposed video coding technique using the two-stage MC significantly outperforms H.263 under identical conditions, especially for sequences with fast camera motion. The performance improvements in peak-to-peak SNR (PSNR) are about 3 dB over the original H.263, which does not use the two-stage MC.

A component separation DPCM Coding system is described which is capable of transmitting a 4 MHz NTSC color TV signal with broadcast quality at a 32.064 Mbit/s rate. The input NTSC color TV signal is first separated into a luminance componentYand two chrominance componentsIandQ. Then, these three components are converted into a TDM-PCM color signal, whereIandQof only odd lines are transmitted and samples in horizontal blanking intervals ofY,I,andQare removed, in order to reduce the transmission rate. This TDM-PCM signal is encoded by a single DPCM coder, which employs a two-dimensional prediction method and a dual word-length coding method. For theYsignal, 4 bit and 8 bit code words are assigned to 29 quantizing levels. For bothIandQsignals, 3 bit and 6 bit code words are assigned to 13 quantizing levels. Coding experiment results show that this coding system is promising for application to broadcast color TV signal transmission at a 32.064 Mbit/s rate.

A composite DPCM coding System was developed, which is capable of coding and transmitting an NTSC color TV signal without component separation at a 32.064 Mbit/s rate. The DPCM prediction method used is based on the algorithm that a luminance component prediction value\hat{y}and a carrier chrominance component prediction value\hat{c}are calculated individually, and then the composite signal prediction value\hat{x}is determined by\hat{x} = \hat{y} + hat{c}. In order to utilize horizontal blanking (HBL) intervals for transmitting active video signals,HBL signals are not transmitted in each line but their representative signals are transmitted once a frame during a vertical blanking interval. A dual word-length coding and quantizing method is adopted, which uses 4 bit and 8 bit words with average word-lengths of 4.4 bits/sample. Codec equipment was fabricated, and coding and transmitting experiments were conducted, using NTT's PCM-100 M digital repeatered line. Experimental results show that this composite DPCM coding system can be employed for digital transmission of NTSC color TV signals, such as color ITV signals, at a 32.064 Mbit/s rate.