Image coding apparatus and method, image decoding apparatus and method, and recording medium

An image coding apparatus comprising:

• filtering means for low-pass filtering and high-pass filtering an input image in the vertical and horizontal directions to generate subbands and then hierarchically filtering a subband comprising a low frequency component;
• code-block generating means for decomposing each subband generated by the filtering means into code-blocks each having a predetermined size in consideration of the characteristics of the input image;
• bit-plane generating means for generating bit-planes including bits from the most significant bit to the least significant bit every code-block;
• coding pass generating means for generating coding passes every bit-plane;
• arithmetic coding means for performing arithmetic coding in the coding passes;
• bit-rate control means for controlling a bit-rate to a target bit-rate on the basis of generated arithmetic codes;
• and
• packet assembling means for adding a header to the arithmetic codes subjected to the bit-rate control to assemble a packet.

An image coding apparatus comprising:

• filtering means for low-pass filtering and high-pass filtering an input image in the vertical and horizontal directions to generate subbands and then hierarchically filtering a subband comprising a low frequency component;
• code-block generating means for decomposing each subband generated by the filtering means into code-blocks each having a predetermined size;
• bit-plane generating means for generating bit-planes including bits from the most significant bit to the least significant bit every code-block;
• coding pass generating means for generating coding passes every bit-plane;
• arithmetic coding means for performing arithmetic coding in the coding passes;
• bit-rate control means for setting a predetermined weighting coefficient value every generated subband, and increasing the weighting coefficient value to preferentially encoding the coding passes in a specific subband or decreasing the weighting coefficient value to truncate the coding pass in the specific subband in order to control a bit-rate to a target bit-rate;
• and
• packet assembling means for adding a header to arithmetic codes subjected to the bit-rate control to assemble a packet, wherein
• when the input image is an interlaced image, the bit-rate control means sets the weighting coefficient value of a predetermined subband to a large value.

An image coding method comprising:

• a filtering step of low-pass filtering and high-pass filtering an input image in the vertical and horizontal directions to generate subbands and then hierarchically filtering a subband comprising a low frequency component;
• a code-block generating step of decomposing each subband generated by the filtering step into code-blocks each having a predetermined size;
• a bit-plane generating step of generating bit-planes including bits from the most significant bit to the least significant bit every code-block;
• a coding pass generating step of generating coding passes every bit-plane;
• an arithmetic coding step of performing arithmetic coding in the coding passes;
• a bit-rate control step of controlling a bit-rate to a target bit-rate on the basis of generated arithmetic codes;
• and
• a packet assembling step of adding a header to the arithmetic codes subjected to the bit-rate control to assemble a packet, wherein
• in the filtering step, a predetermined subband is further filtered in consideration of the characteristics of the input image.

An image coding method comprising:

• a filtering step of low-pass filtering and high-pass filtering an input image in the vertical and horizontal directions to generate subbands and then hierarchically filtering a subband comprising a low frequency component;
• a code-block generating step of decomposing each subband generated by the filtering step into code-blocks each having a predetermined size in consideration of the characteristics of the input image;
• a bit-plane generating step of generating bit-planes including bits from the most significant bit to the least significant bit every code-block;
• a coding pass generating step of generating coding passes every bit-plane;
• an arithmetic coding step of performing arithmetic coding in the coding passes;
• a bit-rate control step of controlling a bit-rate to a target bit-rate on the basis of generated arithmetic codes;
• and
• a packet assembling step of adding a header to the arithmetic codes subjected to the bit-rate control to assemble a packet.

An image coding method comprising:

• a filtering step of low-pass filtering and high-pass filtering an input image in the vertical and horizontal directions to generate subbands and then hierarchically filtering a subband comprising a low frequency component;
• a code-block generating step of decomposing each subband generated in the filtering step into code-blocks each having a predetermined size;
• a bit-plane generating step of generating bit-planes including bits from the most significant bit to the least significant bit every code-block;
• a coding pass generating step of generating coding passes every bit-plane;
• an arithmetic coding step of performing arithmetic coding in the coding passes;
• a bit-rate control step of setting a predetermined weighting coefficient value every generated subband, and increasing the weighting coefficient value to preferentially encoding the coding passes in a specific subband or decreasing the weighting coefficient value to truncate the coding pass in the specific subband in order to control a bit-rate to a target bit-rate;
• and
• a packet assembling step of adding a header to arithmetic codes subjected to the bit-rate control to assemble a packet, wherein
• in the bit-rate control step, when the input image is an interlaced image, the weighting coefficient value of a predetermined subband is set to a large value.

A computer-readable recording medium in which a program to allow a computer to execute a predetermined process is recorded, the program comprising:

• a filtering step of low-pass filtering and high-pass filtering an input image in the vertical and horizontal directions to generate subbands and then hierarchically filtering a subband comprising a low frequency component;
• a code-block generating step of decomposing each subband generated in the filtering step into code-blocks each having a predetermined size;
• a bit-plane generating step of generating bit-planes including bits from the most significant bit to the least significant bit every code-block;
• a coding pass generating step of generating coding passes every bit-plane;
• an arithmetic coding step of performing arithmetic coding in the coding passes;
• a bit-rate control step of controlling a bit-rate to a target bit-rate on the basis of generated arithmetic codes;
• and
• a packet assembling step of adding a header to the arithmetic codes subjected to the bit-rate control to assemble a packet, wherein
• in the filtering step, a predetermined subband is further filtered in consideration of the characteristics of the input image.

A computer-readable recording medium in which a program to allow a computer to execute a predetermined process is recorded, the program comprising:

• a filtering step of low-pass filtering and high-pass filtering an input image in the vertical and horizontal directions to generate subbands and then hierarchically filtering a subband comprising a low frequency component;
• a code-block generating step of decomposing each subband generated in the filtering step into code-blocks each having a predetermined size in consideration of the characteristics of the input image;
• a bit-plane generating step of generating bit-planes including bits from the most significant bit to the least significant bit every code-block;
• a coding pass generating step of generating coding passes every bit-plane;
• an arithmetic coding step of performing arithmetic coding in the coding passes;
• a bit-rate control step of controlling a bit-rate to a target bit-rate on the basis of generated arithmetic codes;
• and
• a packet assembling step of adding a header to the arithmetic codes subjected to the bit-rate control to assemble a packet.

A computer-readable recording medium in which a program to allow a computer to execute a predetermined process is recorded, the program comprising:

• a filtering step of low-pass filtering and high-pass filtering an input image in the vertical and horizontal directions to generate subbands and then hierarchically filtering a subband comprising a low frequency component;
• a code-block generating step of decomposing each subband generated in the filtering step into code-blocks each having a predetermined size;
• a bit-plane generating step of generating bit-planes including bits from the most significant bit to the least significant bit every code-block;
• a coding pass generating step of generating coding passes every bit-plane;
• an arithmetic coding step of performing arithmetic coding in the coding passes;
• a bit-rate control step of setting a predetermined weighting coefficient value every generated subband, and increasing the weighting coefficient value to preferentially encoding the coding passes in a specific subband or decreasing the weighting coefficient value to truncate the coding pass in the specific subband in order to control a bit-rate to a target bit-rate;
• and
• a packet assembling step of adding a header to arithmetic codes subjected to the bit-rate control to assemble a packet, wherein
• in the bit-rate control step, when the input image is an interlaced image, the weighting coefficient value of a predetermined subband is set to a large value.

An image decoding apparatus comprising:

• packet disassembling means for disassembling each encoded code-stream generated as a packet into a header and arithmetic codes;
• decoding means for decoding the arithmetic codes;
• coding pass decoding means for decoding coding passes every bit-plane;
• code-block reconstructing means for reconstructing each code-block on the basis of bit-planes including bits from the most significant bit to the least significant bit;
• subband generating means for composing the code-blocks into each subband;
• and
• filtering means for hierarchically low-pass filtering and high-pass filtering a subband comprising a low frequency component in the vertical and horizontal directions, wherein
• the filtering means further filters a subband comprising a horizontal low frequency component and a vertical high frequency component.

An image decoding method comprising:

• a packet disassembling step of disassembling each encoded code-stream generated as a packet into a header and arithmetic codes;
• a decoding step of decoding the arithmetic codes;
• a coding pass decoding step of decoding coding passes every bit-plane;
• a code-block reconstructing step of reconstructing each code-block on the basis of the bit-planes including bits from the most significant bit to the least significant bit;
• a subband generating step of composing the code-blocks into each subband;
• and
• a filtering step of hierarchically low-pass filtering and high-pass filtering a subband comprising a low frequency component in the vertical and horizontal directions, wherein
• in the filtering step, a subband comprising a horizontal low frequency component and a vertical high frequency component is further filtered.

A computer-readable recording medium in which a program to allow a computer to execute a predetermined process is recorded, the program comprising:

• a packet disassembling step of disassembling each encoded code-stream generated as a packet into a header and arithmetic codes;
• a decoding step of decoding the arithmetic codes;
• a coding pass decoding step of decoding coding passes every bit-plane;
• a code-block reconstructing step of reconstructing each code-block on the basis of the bit-planes including bits from the most significant bit to the least significant bit;
• a subband generating step of composing the code-blocks into each subband;
• and
• a filtering step of hierarchically low-pass filtering and high-pass filtering a subband comprising a low frequency component in the vertical and horizontal directions, wherein
• in the filtering step, a subband comprising a horizontal low frequency and a vertical high frequency is further filtered.