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Method and apparatus for reconstructing an image blockRelated Patent Categories: Pulse Or Digital Communications, Bandwidth Reduction Or Expansion, Television Or Motion Video Signal, Predictive, Motion VectorMethod and apparatus for reconstructing an image block description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070253486, Method and apparatus for reconstructing an image block. Brief Patent Description - Full Patent Description - Patent Application Claims
DOMESTIC PRIORITY INFORMATION [0001] This application claims the benefit of priority on U.S. Provisional Application No. 60/723,474 filed Oct. 5, 2005; the entire content of which is hereby incorporated by reference. FOREIGN PRIORITY INFORMATION [0002] This application claims the benefit of priority on Korean Patent Application No. 10-2006-0068314 filed Jul. 21, 2006; the entire content of which is hereby incorporated by reference. BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The present invention relates, in general, to methods of encoding and decoding video signals. [0005] 2. Description of the Related Art [0006] A Scalable Video Codec (SVC) is a scheme for encoding video signals at the highest image quality when encoding the video signals, and enabling image quality to be secured to some degree even if only part of the entire picture (frame) sequence generated as a result of the encoding (a sequence of frames intermittently selected from the entire sequence) is decoded. [0007] Even if only a partial sequence of a picture sequence encoded by a scalable scheme is received and processed, image quality can be secured to some degree. However, if the bit rate is decreased, the deterioration in image quality becomes serious. In order to solve the problem, a separate sub-picture sequence for a low bit rate, for example, a picture sequence of small screens and/or a picture sequence having a small number of frames per second, can be provided. [0008] This sub-picture sequence is called a base layer, and a main picture sequence is called an enhanced layer. The base layer and the enhanced layer are obtained by encoding the same video signal source, and redundant information exists in the video signals of the two layers. Therefore, when the base layer is provided, an interlayer prediction method can be used to improve coding efficiency. [0009] Further, in order to improve the Signal-to-Noise Ratio (SNR) of a base layer, that is, to enhance image quality, an enhanced layer may be used, which is called SNR scalability, Fine Granular Scalability (FGS), or progressive refinement. [0010] According to FGS, transform coefficients corresponding to respective pixels, for example, Discrete Cosine Transform (DCT) coefficients, are separately encoded into a base layer and an enhanced layer, depending on the resolution of bit representation. When a transmission environment is bad, the transmission of the enhanced layer is omitted, so that the bit rate can be decreased while the quality of a decoded image is deteriorated. That is, FGS compensates for loss occurring during a quantization process, and provides high flexibility enabling a bit rate to be controlled in response to a transmission or decoding environment. [0011] For example, if a transform coefficient is quantized using a quantization step size (that is, QP), for example, QP=32, to generate a base layer, a first FGS enhanced layer is generated by quantizing the difference between an original transform coefficient and a transform coefficient obtained by inversely quantizing the quantized coefficient of the base layer, using a quantization step size corresponding to quality higher than QP=32, for example, QP=26. Similarly, a second FGS enhanced layer is generated by quantizing the difference between the original transform coefficient and a transform coefficient obtained by inversely quantizing the sum of the quantized coefficients of the base layer and the first FGS enhanced layer, using a quantization step size, for example, QP=20. [0012] However, in a conventional FGS coding method, only a quality base layer, that is, a picture of an FGS base layer, is used to generate an FGS enhanced layer. This means that temporally redundant information existing between temporally adjacent quality enhanced layers, that is, pictures of an FGS enhanced layer, are not used. [0013] In order to use such temporal redundancy in the FGS enhanced layer, a method of utilizing an adjacent quality enhanced layer as well as a quality base layer to predict a current FGS enhanced layer is proposed. This method is called a Progressive FGS (PFGS), and the structure of such a PFGS scheme is shown in FIG. 1. [0014] As shown in FIG. 1, an adaptive reference block formation function receives a base layer collocated block Xb and a FGS enhanced layer reference block Re, and produces an adapted reference block Ra for use in reconstructing a current image block X in a current frame of the FGS layer that is being reconstructed. The collocated block Xb is the block in the base layer that is collocated with respect to the current image block X. Namely, the collocated block Xb is in a base layer frame temporally coincident with the current frame of the FGS layer, and the collocated block Xb is in the same relative position within the base layer frame as the current image block X in the current frame of the FGS layer. [0015] The collocated block Xb includes a reference picture index that indicates a reference base layer frame. The collocated block Xb also includes a motion vector. As shown in FIG. 1, the motion vector points to a base layer reference block Rb in the reference base layer frame. The FGS enhanced layer reference block Re is a collocated block with respect to the base layer reference block Rb. Namely, the frame in the FGS layer temporally coincident with the reference frame in the base layer indicated by the reference picture index of the collocated block Xb serves as the FGS enhanced layer reference frame. Further, the motion vector of the collocated block Xb is used as the motion vector in the FGS enhanced layer reference frame to obtain the FGS enhanced layer reference block Re. [0016] The FGS enhanced layer reference block Re is a difference or error signal representing enhancement quality. As such, the adaptive reference block formation function adds the FGS enhanced layer reference block Re to the collocated block Xb at a transform coefficient level to obtain the adapted reference block Ra. Then, as shown in FIG. 1, a reconstruction function reconstructs the current image block X by combining an encoded block Rd for the current image block X with the adapted reference block Ra in the well-known manner. [0017] However, the resolution of bit representation of an image may vary due to the difference between the quantization step sizes of the FGS base layer and the FGS enhanced layer, so that the motion vector of the FGS base layer collocated block Xb may not be identical to that of the FGS enhanced layer block X. This means that coding efficiency may be decreased. SUMMARY OF THE INVENTION [0018] The present invention relates to a method of reconstructing a current block in a first picture layer. [0019] In one embodiment, a motion vector for the current block is generated based on motion vector information for a block in a second picture layer and motion vector difference information associated with the current block. The second picture layer has lower quality pictures than pictures in the first picture layer, and the block of the second picture layer being temporally associated with the current block in the first picture layer. The current block is reconstructed using the generated motion vector and a reference picture. [0020] In one embodiment, a picture in the first picture layer is determined as the reference picture based on a reference picture index for the block in the second picture layer. Continue reading about Method and apparatus for reconstructing an image block... Full patent description for Method and apparatus for reconstructing an image block Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method and apparatus for reconstructing an image block patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method and apparatus for reconstructing an image block or other areas of interest. ### Previous Patent Application: Coding system and method, encoding device and method, decoding device and method, recording device and method, and reproducing device and method Next Patent Application: Wavelet transform aparatus and method, scalable video coding apparatus and method employing the same, and scalable video decoding apparatus and method thereof Industry Class: Pulse or digital communications ### FreshPatents.com Support Thank you for viewing the Method and apparatus for reconstructing an image block patent info. IP-related news and info Results in 0.18772 seconds Other interesting Feshpatents.com categories: Novartis , Pfizer , Philips , Polaroid , Procter & Gamble , 174 |
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