Method and apparatus for encoding and decoding data with altered bit sequence
Provided are methods and apparatuses for encoding data. One method of encoding data includes generating second data by altering locations of bits within first data to be encoded next based on values of bits within at least one piece of previously encoded data; and entropy-encoding the second data. Also provided are methods and apparatuses for decoding data.
1. A method of encoding data, the method comprising:
generating second data by altering locations of bits within first data to be encoded based on previously encoded data; and
entropy-encoding the second data,
wherein the generating of the second data comprises:
for each bit within the first data, calculating a probability that the bit has a predetermined value based on values of bits within previously encoded data; and
rearranging bits within the first data based on the calculated probabilities.
2. The method of claim 1 , wherein the predetermined value is a value of ‘1.’
3. The method of claim 1 , wherein the predetermined value is a value of ‘0.’
4. The method of claim 1 , wherein the bits are rearranged such that bits with higher probabilities within the first data are located in lower bits within the second data.
5. The method of claim 1 , wherein the bits are rearranged such that bits with higher probabilities within the first data are located in higher bits within the second data.
6. The method of claim 1 , wherein the probability is calculated based on a number of times that a bit has the predetermined value at the same location within at least one piece of the previously encoded data.
7. The method of claim 1 , wherein the entropy-encoding of the second data comprises encoding the second data by performing at least one of Huffman encoding and Golomb encoding.
8. A non-transitory computer readable recording medium having recorded thereon a computer program for implementing the method of claim 1 .
9. A method of decoding data, the method comprising:
obtaining first data by decoding encoded data; and
generating second data by altering locations of bits within first data based on previously decoded data,
wherein the generating of the second data comprises:
for each bit within the first data, calculating a probability that the bit has a predetermined value based on values of bits within the previously decoded data; and rearranging bits within the first data based on the calculated probabilities.
10. The method of claim 9 , wherein the predetermined value is a value of ‘1.’
11. The method of claim 9 , wherein the predetermined value is a value of ‘0.’
12. The method of claim 9 , wherein the bits are rearranged such that bits with higher probabilities within the first data are located in lower bits within the second data.
13. The method of claim 9 , wherein the bits are rearranged such that bits with higher probabilities within the first data are located in higher bits within the second data.
14. The method of claim 9 , wherein the probability is calculated based on a number of times that a bit has the predetermined value at of the same location within at least one piece of the previously decoded data.
15. The method of claim 9 , wherein the entropy-decoding of the encoded data to obtain the first data comprises performing at least one of Huffman decoding and Golomb decoding.
16. A non-transitory computer readable recording medium having recorded thereon a computer program for implementing the method of claim 9 .
17. An apparatus for encoding data, the apparatus comprising:
a bit location altering unit which generates second data by altering locations of bits within first data to be encoded based on previously encoded data; and
a data encoding unit which encodes the second data,
wherein the bit altering unit comprises:
a probability calculating unit which, for each bit within the first data, calculates a probability that the bit has a predetermined value based on values of bits within previously encoded data; and
a rearranging unit that rearranges bits within the first data based on the calculated probabilities.
18. An apparatus for decoding data, the apparatus comprising:
a decoding unit which obtains first data by decoding encoded data; and
a bit location altering unit which generates second data by altering locations of bits within first data based on previously decoded data,
wherein the bit location altering unit comprises:
a probability calculation unit which, for each bit within the first data, calculates a probability that the bit has predetermined values based on values, of bits within the previously decoded data, and
a bit rearranging unit that rearranges bits within the first data based on the calculated probabilities.