초록 ▼

This invention provides methods and apparatus as a countermeasure to image distorting. Several image distorting algorithms have been developed that are intended to attack and obliterate robust relatively invisible image watermarks. These algorithms modify a watermarked image so subtly by geometric d

This invention provides methods and apparatus as a countermeasure to image distorting. Several image distorting algorithms have been developed that are intended to attack and obliterate robust relatively invisible image watermarks. These algorithms modify a watermarked image so subtly by geometric distortion that the modification is essentially unnoticeable to a human observer. However, their effect on imbedded relatively invisible watermarks can be devastating, often successfully rendering them unextractable. A method of the present invention involves detecting the presence of distortion in a presumed distorted image, then measuring the magnitude and type of distortion, and finally creating a reoriented image from which the measured distortion has been removed. Once image distortion is removed, conventional invisible watermark extraction methods can be employed to extract the watermark from the reoriented image.

대표청구항 ▼

This invention provides methods and apparatus as a countermeasure to image distorting. Several image distorting algorithms have been developed that are intended to attack and obliterate robust relatively invisible image watermarks. These algorithms modify a watermarked image so subtly by geometric d

This invention provides methods and apparatus as a countermeasure to image distorting. Several image distorting algorithms have been developed that are intended to attack and obliterate robust relatively invisible image watermarks. These algorithms modify a watermarked image so subtly by geometric distortion that the modification is essentially unnoticeable to a human observer. However, their effect on imbedded relatively invisible watermarks can be devastating, often successfully rendering them unextractable. A method of the present invention involves detecting the presence of distortion in a presumed distorted image, then measuring the magnitude and type of distortion, and finally creating a reoriented image from which the measured distortion has been removed. Once image distortion is removed, conventional invisible watermark extraction methods can be employed to extract the watermark from the reoriented image. able memory comprises: a first sub-memory for storing a VLC table corresponding to a macroblock having one block where an object is present and providing a coded block pattern corresponding to the macroblock having one block where the object is present; a second sub-memory for storing a VLC table corresponding to a macroblock having two blocks where an object is present and providing a coded block pattern corresponding to the macroblock having two blocks where the object is present; a third sub-memory for storing a VLC table corresponding to a macroblock having three blocks where an object is present and providing a coded block pattern corresponding to the macroblock having three blocks where the object is present; and a fourth sub-memory for storing a VLC table corresponding to a macroblock having four blocks where an object is present and providing a coded block pattern corresponding to the macroblock having four blocks where the object is present. 3. In an object-based video decoding system comprising a shape information decoding unit for decoding an input shape bitstream and providing a reconstructed shape bitstream and a texture information decoding unit including a demultiplexer, variable length decoding (VLD) unit, inverse scanning, inverse quantizer, and inverse transform unit for decoding an input texture bitstream, a coded block pattern decoding apparatus comprising: a non-transparent block counter for detecting the number of non-transparent blocks within the macroblock to be decoded using said reconstructed shape information and generating first and second switching control signals according to the detected number of non-transparent blocks; a first switch for controlling a path of the coded block pattern output from said demultiplexer according to the first switching control signal generated from said non-transparent block counter; a VLD table memory for providing a coded block pattern decoded according to VLD tables having different length using a signal applied via the first switch as an address; and a second switch for coupling the coded block pattern generated from said VLD table memory to an output path according to the second switching control signal generated from said non-transparent block counter; and switching means for allowing or not allowing the texture bitstream output from said demultiplexer to be transmitted to said VLD unit according to the switching control signal output from said coded block pattern decoding means. 4. The apparatus according to claim 3, wherein said non-transparent block counter detects blocks having object information using said reconstructed shape information, said block having a predetermined size in the macroblock decoded, counts the blocks having the object information, and generates said first and second switching control signals according to the counted value. 5. The apparatus according to claim 3, wherein said VLD table memory comprises: a first sub-memory for storing a VLD table corresponding to a macroblock having one block where an object is present and providing a coded block pattern corresponding to the macroblock having one block where the object is present; a second sub-memory for storing a VLD table corresponding to a macroblock having two blocks where an object is present and providing a coded block pattern corresponding to the macroblock having two blocks where the object is present; a third sub-memory for storing a VLD table corresponding to a macroblock having three blocks where an object is present and providing a coded block pattern corresponding to the macroblock having three blocks where the object is present; and a fourth sub-memory for storing a VLD table corresponding to a macroblock having four blocks where an object is present and providing a coded block pattern corresponding to the macroblock having four blocks where the object is present. 6. In an object-based video coding system and object based decoding system, in which the coding system comprises a shape information encoding unit for encoding input shape information and providing reconstructed shape information and a texture information encoding unit including a transform unit, a quantizer, a scanning unit, and a variable length coding (VLC) unit for encoding input texture information, and a coded block pattern encoding apparatus and, the decoding system comprises a shape information decoding unit for decoding an input shape bitstream and providing a reconstructed shape bitstream and a texture information decoding unit including a demultiplexer, a variable length decoding (VLD) unit, an inverse scanning, an inverse quantizer, and an inverse transform unit for decoding an input texture bitstream, and a coded block pattern decoding apparatus, the coding system comprising: a coding non-transparent block counter for detecting the number of non-transparent blocks within the macroblock using said input reconstructed shape information and generating first and second switching control signals according to the detected number of non-transparent blocks; a coded block pattern decision unit for generating numerical information for reading the coded block pattern according to the number of non-transparent blocks based upon said input reconstructed shape information; a first switch for coupling information generated from said coded block pattern decision unit to one of a plurality of paths according to the first switching control signal generated from said non-transparent block counter; a VLC table memory for providing the encoded coded block pattern according to information obtained through the first switch; a second switch for coupling the coded block pattern generated from said VLC table memory to an output path according to the second switching control signal generated from said non-transparent block counter; and multiplexing means for multiplexing the coded block pattern generated from said coded block pattern decision and encoding means and texture information generated from said VLC unit to provide an output. 7. The system according to claim 6, wherein the decoding system further comprises: a decoding non-transparent block counter for detecting the number of non-transparent blocks within the macroblock to be decoded using said reconstructed shape information and generating third and fourth switching control signals according to the detected number of non-transparent blocks; a third switch for controlling a path of the coded block pattern output from said demultiplexer according to the third switching control signal generated from said non-transparent block counter; a VLD table memory for providing a coded block pattern decoded according to VLD tables having different length using a signal applied via the third switch as an address; a fourth switch for coupling the coded block pattern generated from said VLD table memory to an output path according to the fourth switching control signal generated from said non-transparent block counter; and switching means for allowing or not allowing the texture bitstream output from said demultiplexer to be transmitted to said VLD unit according to the switching control signal output from said coded block pattern decoding means. 8. In an object-based video coding system and object based decoding system, in which the coding system comprises a shape information encoding unit for encoding input shape information and providing reconstructed shape information and a texture information encoding unit including a transform unit, a quantizer, a scanning unit, and a variable length coding (VLC) unit for encoding input texture information, and a coded block pattern encoding apparatus and, the decoding system comprises a shape information decoding unit for decoding an input shape bitstream and providing a reconstructed shape bitstream and a texture information decoding unit including a demultiplexer, a variable length decoding (VLD) unit, an inverse scanning, an inverse quantizer, and an inverse transform unit for decoding an input texture bitstream, and a coded block pattern decoding apparatus, the decoding system comprising: a decoding non-transparent block counter for detecting the number of non-transparent blocks within the macroblock to be decoded using said reconstructed shape information and generating third and fourth switching control signals according to the detected number of non-transparent blocks; a third switch for controlling a path of the coded block pattern output from said demultiplexer according to the third switching control signal generated from said non-transparent block counter; a VLD table memory for providing a coded block pattern decoded according to VLD tables having different length using a signal applied via the third switch as an address; a fourth switch for coupling the coded block pattern generated from said VLD table memory to an output path according to the fourth switching control signal generated from said non-transparent block counter; and switching means for allowing or not allowing the texture bitstream output from said demultiplexer to be transmitted to said VLD unit according to the switching control signal output from said coded block pattern decoding means. 9. The system of claim 8, wherein the coding system further comprises: a coding non-transparent block counter for detecting the number of non-transparent blocks within the macroblock using said input reconstructed shape information and generating first and second switching control signals according to the detected number of non-transparent blocks; a coded block pattern decision unit for generating numerical information for reading the coded block pattern according to the number of non-transparent blocks based upon said input reconstructed shape information; a first switch for coupling information generated from said coded block pattern decision unit to one of a plurality of paths according to the first switching control signal generated from said non-transparent block counter; a VLC table memory for providing the encoded coded block pattern according to information obtained through the first switch; and a second switch for coupling the coded block pattern generated from said VLC table memory to an output path according to the second switching control signal generated from said non-transparent block counter; and multiplexing means for multiplexing the coded block pattern generated from said coded block pattern decision and encoding means and texture information generated from said VLC unit to provide an output.