Showing papers by "Woo-Jin Han published in 2009"

Method and apparatus for encoding and decoding image by using filtered prediction block

Abstract: A prediction block of a current block is created by performing intra prediction or inter prediction on the current block. The prediction block is filtered by using a predetermined filter. The current block is encoded based on the filtered prediction block. A compression rate of image encoding may be substantially improved by more accurately performing a prediction encoding.

Method and apparatus for encoding and decoding image by using multiple reference-based motion prediction

Abstract: Provided are a method and apparatus for encoding an image by using motion prediction and a method and apparatus for decoding an image by using motion prediction. The method of encoding an image by using motion prediction, the method includes: determining at least one candidate predictor set including at least one candidate predictor within a candidate predictor range away from a location of a current predictor in a reference frame; determining a reference predictor based on a distortion rate of hypothesis predictors determined according to the at least one candidate predictor of each of the at least one candidate predictor set; performing motion prediction with regard to a current frame by using a reference block corresponding to the reference predictor and a current block; and encoding image data including the current frame based on a result of the motion prediction.

Method and apparatus for encoding and decoding image by using sub-pixel-based motion prediction

Abstract: Provided are a method and apparatus for encoding an image by using sub-pixel-based motion prediction and a method and apparatus for decoding an image by using sub-pixel-based motion prediction. The method of encoding an image includes determining weights for respective low-precision sub-pixels for interpolation between the low-precision sub-pixels, determining an interpolation direction for the low-precision sub-pixels based on a position of a high-precision sub-pixel between the low-precision sub-pixels, and performing motion prediction in units of high-precision sub-pixels determined by interpolation which applies the interpolation direction and the weights to the low-precision sub-pixels.

Method and apparatus for encoding and decoding an image based on plurality of reference pictures

Abstract: A method and apparatus for encoding and decoding an image using a plurality of reference pictures. In an exemplary embodiment, the method of encoding an image comprises: generating information about transforms between a first picture and a second picture; generating a reference picture by transforming the second picture based on the generated information about transforms; predicting a current block of a current picture based on at least one of the reference picture and the first picture; and encoding the current block based on the predicting. Therefore, prediction encoding based on more accurate prediction is possible, thereby increasing a compression ratio of image encoding.

Method and apparatus for encoding and decoding an image using a reference picture

Abstract: A method and apparatus for encoding and decoding an image by performing motion prediction and compensation on pictures in a group of pictures by selectively using a high-quality key picture that is previously encoded and restored, and a second picture that is previously encoded and restored. The method of encoding an image improves the prediction efficiency of an image by storing a key picture, which is encoded and restored to a high quality by reducing a loss caused by a quantization error using a small quantization coefficient, in a first storage unit and storing a previously encoded and restored second picture in a second storage unit, and then performing motion prediction and compensation by selectively using the key picture stored in the first storage unit and the second picture stored in the second storage unit while encoding a next picture in a group of pictures.

Method and apparatus for encoding and decoding based on inter prediction using image inpainting

Abstract: Provided are a method and apparatus for encoding and decoding based on inter prediction. In the method of encoding based on inter prediction, image inpainting is performed by searching for at least one reference picture by using pixels that are adjacent to the boundary between a current block and a previously encoded region of a current picture and are included in the previously encoded region, and the current block is encoded based on a predicted block obtained as the result of performing image inpainting. Accordingly, it is possible to precisely generate a predicted block, thereby improving the compression rate of image encoding.

Directional Multi-hypothesis Prediction for Improving H.264/AVC Video Coding

Abstract: In this letter, we propose efficient multi-hypothesis prediction (MHP) algorithms for high performance video codec. First, candidate MHPs are generated by combining the seed predictors around the initial predictor which is obtained by motion estimation. Among candidate MHPs, we select the optimal MHP predictor which have the lowest rate-distortion (RD) cost and signal the index as side information. We also propose directional MHP (DMH), which combines only two predictors along the predefined direction to minimize both encoding complexity and signaling overhead. In the experimental results, proposed MHP algorithms show better performance than H.264/AVC. Specifically, the average bit saving of DMH over H.264/AVC is up to 9.55%. The results also indicate that the performance is better at the high bit rate.

Method and apparatus for encoding and decoding at least one image frame that is artificially inserted into image sequence

Abstract: Provided are a method and apparatus for encoding and decoding at least one image frame artificially inserted by a user among a plurality of image frames of an image sequence by using a parameter regarding characteristics of the image frame.

Encoding method and device employing motion prediction by means of multi-referencing, and a decoding method and device employing motion prediction by means of multi-referencing

Abstract: The present invention relates to an image-encoding method and device based on motion prediction, and to an image-decoding method and device based on motion prediction. The image-encoding method according to the present invention comprises the operations of: determining, in a reference frame, at least one candidate-estimator collection containing at least one candidate estimator in a range of candidate estimators centred on the current estimator on the reference frame; determining a reference estimator on the basis of the error rate of hypothetical estimators determined by using a candidate estimator of the respective candidate-estimator collection in at least one candidate-estimator collection determined in the way described hereinabove; carrying out motion prediction for the current frame, using the current block and a reference block corresponding to the reference estimator; and encoding image data including the current frame on the basis of the results of the motion prediction. This allows the prediction performance between screens to be improved.