Video coding

Abstract

Digitalized video images are compressed in several steps in order to provide a system for transmitting moving video pictures via narrow band channels, such as the telephone network. The system is based on any extension of the bit-plane coding technique to video sequences and lossy conditions. The compression technique can also be advantageously used in a lossless compression system. The system involves the steps of bit plane representation and skipping the least significant bit plane(s), shifting the pixels, coding with a Gray code, the use of segmentation, and motion-estimation/motion compensation and application of a transmit/not transmit/motion compensate (TX/NT/MC) procedure, exploiting of the temporal redundancy of two corresponding bit planes via an XOR operation on two successive images, and a plane-by-plane application of an extended RLEID technique. The RLEID technique includes coding a run of like binary symbols with one word, the run including a transition between the penultimate and ultimate binary symbol.

1 . A method of lossy compression of a digitalized image, characterized by the steps of 
 representing the image with a bit plane representation, and    reducing the information content in the image by removing at least the least significant bit plane of the bit plane represented image.    
     
     
         2 . A method according to    claim 1   , characterized in 
 that the remaining binary bit planes are shifted into the least significant positions and that the positions made vacant when the planes are shifted are padded with zeroes, and    that the pixels of the shifted bit planes are coded with a Gray code.    
     
     
         3 . A method according to    claim 2   , characterized in that an exclusive OR (XOR) operation is performed between the bits of two bit planes from the different images resulting in a third bit plane indicating the bits which are different between the two different bit planes.  
     
     
         4 . A method according to    claim 3   , characterized in that a binary output sequence from the XOR operation is divided into runs in such a manner that there is one transition between the penultimate and the ultimate binary symbol in each run, and encoding each such run by one code word.  
     
     
         5 . A device for compressing bit plane represented video images, characterized by means for skipping the least significant bit plane or bit planes.  
     
     
         6 . A device according to    claim 5   , characterized by means connected to the skipping means for shifting the planes and for padding the positions made vacant when the planes are shifted with zeroes, and by means for coding the pixels of the shifted bit planes with a Gray code.  
     
     
         7 . A device according to    claim 6   , characterized by means connected to the shifting and zero padding means for performing an exclusive OR (XOR) operation between the bits of two bit planes from the different images resulting in a third bit plane indicating the bits which are different between the two different bit planes.  
     
     
         8 . A device according to    claim 7   , characterized by means connected to the Xor operation means for dividing a binary output sequence from the XOR operation into runs in such a manner that there is one transition between the penultimate and the ultimate binary symbol in each run, and by means for encoding each such run by one code word.  
     
     
         9 . A method of evaluating and/or exploiting the temporal redundancy of bit planes of two different bit plane represented images, characterized in performing an exclusive OR (XOR) operation between the bits of two bit planes from the different images resulting in a third bit plane indicating the bits which are different between the two different bit planes.  
     
     
         10 . A method according to    claim 9   , characterized in that the exclusive OR (XOR) operation is performed on two corresponding bit planes having the same significance.  
     
     
         11 . A method according to one of claims  9 - 10 , characterized in that the two images are two successive images of a moving picture.  
     
     
         12 . A device for evaluating and/or exploiting the temporal redundancy of bit planes of two different bit plane represented images, characterized by means for performing an exclusive OR (XOR) operation of the two different bit planes and for forming a third bit plane indicating the bits which are different between the two different bit planes.  
     
     
         13 . A device according to    claim 12   , characterized by means for performing the XOR operation on two successive frames of a moving picture.  
     
     
         14 . A system for transmission of bit plane represented moving pictures comprising a transmitter and a receiver, characterized in that the transmitter comprises means for skipping one or several bit planes of an input bit plane represented moving picture, means connected to the skipping means for shifting the pixels or the bit planes of such a plane skipped image, means connected to the shifting means for padding the positions made vacant by the shifting of the pixels with zeroes, means connected to the zero padding means for coding and the pixels of the shifted bit planes with a Gray code, means connected to the Gray coding means for comparing two bit planes, of two different images using an exclusive OR (XOR) operation and for forming a third bit plane indicating the bits which are different between the two different bit planes, means connected to the XOR operation means for coding and transmitting an output sequence from the XOR operation means with an entropy code and that the receiver comprises corresponding means for decoding and decompressing received pictures.  
     
     
         15 . A system according to    claim 14   , characterized by means connected to the Gray coding means for carrying out a segmentation of a plane skipped image, and for performing a transmit/not transmit (TX/NT) operation on such a segmented image.  
     
     
         16 . A system according to    claim 14   , characterized by means connected to the Gray coding means for carrying out a segmentation of a plane skipped image, means for performing a motion estimation (ME), and means for performing a transmit/motion compensation/not transmit (TX/MC/NT) operation on such a segmented image.  
     
     
         17 . A method of encoding a sequence of binary symbols, characterized in that the binary sequence is divided into runs in such a manner that there is one transition between the penultimate and the ultimate binary symbol in each run and encoding each such run by one code word.  
     
     
         18 . A device for encoding a sequence of binary symbols, characterized by means for dividing the binary sequence into runs in such a manner that there is one transition between the penultimate and the ultimate binary symbol in each run and by means for encoding each such run by one code word.  
     
     
         19 . A method of lossless compression of moving pictures comprising the step of bit plane representing the frames of a moving picture, charactarized in that an XOR operation is performed between a first bit plane of a first frame of the moving picture and a corresponding bit plane of a second frame resulting in a third bit plane, and that the third bit plane is used instead of the second bit plane in further compression processing.  
     
     
         20 . A device for lossless compression of bit plane represented moving pictures, characterized by means for performing an XOR operation between a first bit plane of a first frame of the moving picture and a corresponding bit plane of a second frame resulting in a third bit plane, and by means for outputting the third bit plane instead of the second bit plane to any other means arranged for further compression processing.