Block coding/decoding method and apparatus for increasing code rate

1. A block encoding method, comprising steps of: determining whether an original block of m bits is a (2N−1) st block of m bits, “m” and N being positive integers; and encoding, if the original block of m bits is the (2N−1) st block of m bits, the original block of m bits as an A type weighted block of n bits having a preselected number of “1” bits and “0” bits and, if otherwise, encoding the original block of m bits as a B type weighted block of n bits 7 having another pre-selected number of “1” bits and “0” bits where “n” being an odd integer larger than “m”, wherein both A type weighted block and its corresponding B type weighted block are combined to form a balance coding block in which the bit number of “1” is equal to that of “0”.

2. The method of claim 1 , wherein the bit number “a” of bit “1” in the A type weighted block of n bits satisfies a relation 2 m< n C a , “a” being a positive integer, and the bit number of “1” in the B type weighted block of n bits is given by “n−a”.

3. A block decoding method, comprising steps of: determining whether a weighted block of n bits is an A type weighted block of n bits having a preselected number of “1” bits and “0” bits, or a B type weighted block of n bits, having another preselected number of “1” bits and “0” bits, where “n” being an odd integer; and decoding, if the weighted block of n bits is the A type weighted block of n bits, the A type weighted block of n bits as a (2N−1) st original block of m bits and, if otherwise, decoding the B type weighted block of n bits as a 2N th original block of m bits, N being a positive integer and “m” being a positive integer smaller than “n”, wherein both A type weighted block and its corresponding B type weighted block are combined to form a balance coding block in which the bit number of “1” is equal to that of “0”.

4. The method of claim 5 , wherein the bit number “a” of “1” in the A type weighted block of n bits satisfies a relation 2 m < n C a .

5. A coding/decoding apparatus, comprising: a first buffer for outputting a digitalized image signal on a basis of an original block of in bits and generating a timing signal for notifying when the original block is outputted, “m” being a positive integer; a first control part for determining whether the original block of m bits is a (2N−1) st original block of m bits, based on the timing signal, N being a positive integer; an encoding part for encoding, if the original block of in bits is the (2N−1) st original block of m bits, the original block of m bits as an A type weighted block of n bits having a preselected number of “1” bits and “0” bits, or a B type weighted block of n bits and, if otherwise, encoding the original block of m bits as a B type weighted block of n bits having another preselected number of “1” bits and “0” bits, where “n” being an odd integer larger than “m”, wherein both A type weighted block and its corresponding B type weighted block are combined to form a balance coding block in which the bit number of “1” is equal to that of “0”; a storage medium for storing the encoded block of n bits; a second buffer for outputting the encoded block stored at the storage medium on a basis of n bits and generating a second timing signal for notifying when the encoded block is outputted; a second control part for determining whether the encoded block of n bits is the A type block of n bits based on the second timing signal; and a decoding part for decoding, if the encoded block of n bits is the A type block of n bits, the encoded block of n bits as the (2N−1) st original block of m bits and if otherwise, decoding the weighted block of n bits as the 2N th original block of m bits.

6. The apparatus of claim 5 , wherein the bit number “a” of bit “1” in the A type weighted block of n bits satisfies a relation 2 m < n C a , “a” being a positive integer, and the bit number of “1” in the B type weighted block of n bits is given by “n−a”.