Method and apparatus for transformation and inverse transformation of image for image compression coding

An apparatus for one-dimensional inverse transformation for digital image compression, comprising:

• a zero detector for determining whether all values of one-dimensional input data are 0 and generating a first or second control signal in accordance with the determined result;
• inverse transformation means for performing a one-dimensional inverse transformation operation for the one-dimensional input data in response to said second control signal from said zero detector;
• and
• a switch for selecting the output of said inverse transformation means in response to said second control signal from said zero detector and said input data in response to said first control signal from said zero detector, respectively.

An apparatus for one-dimensional transformation/inverse transformation for digital image compression, comprising:

• a zero detector for determining whether all values of one-dimensional input data are 0 and generating a first or second control signal in accordance with the determined result;
• transformation/inverse transformation means for selectively performing a one-dimensional transformation operation or one-dimensional inverse transformation operation for the one-dimensional input data in response to said second control signal from said zero detector;
• and
• a switch for selecting the output of said transformation/inverse transformation means in response to said second control signal from said zero detector and said input data in response to said first control signal from said zero detector, respectively.

An apparatus for one-dimensional transformation/inverse transformation for digital image compression, comprising:

• transformation/inverse transformation means for selectively performing a one-dimensional transformation operation or a one-dimensional inverse transformation operation for information of input data of a smaller unit than a bit unit of the input data;
• a zero detector for determining whether all values of said information of the smaller unit than the bit unit of said input data are 0 and generating a first or second control signal in accordance with the determined result to control the operation of said transformation/inverse transformation means;
• a switch for selecting the output of said transformation/inverse transformation means in response to said second control signal from said zero detector and said input data in response to said first control signal from said zero detector, respectively;
• a shift register for shifting and storing input information by the number of bits of a transformation/inverse transformation unit;
• and
• an adder for adding the output of said switch to the information stored in said shift register.

An apparatus for two-dimensional transformation/inverse transformation for digital image compression, comprising:

• an input buffer for storing external input data with a certain bit length and output data from a transposition memory;
• a zero detector for determining whether all values of output data from said input buffer are 0 and generating a first or second control signal in accordance with the determined result;
• transformation/inverse transformation means for selectively performing a one-dimensional transformation operation or a one-dimensional inverse transformation operation for the output data from said input buffer;
• a switch for selecting the output of said transformation/inverse transformation means in response to said second control signal from said zero detector and said output data from said input buffer in response to said first control signal from said zero detector, respectively;
• an output buffer for sequentially storing output data from said switch;
• said transposition memory adapted for storing output data from said output buffer to transpose it on a two-dimensional plane and transferring the results of transformation/inverse transformation in one direction to said input buffer for the two-dimensional transformation/inverse transformation;
• and
• a clipping part for clipping the output data from said output buffer.

An apparatus for two-dimensional transformation/inverse transformation for digital image compression, comprising:

• an input buffer for storing external input data with a certain bit length and output data from a transposition memory;
• transformation/inverse transformation means for selectively performing a one-dimensional transformation operation or a one-dimensional inverse transformation operation for information of output data from said input buffer, of a smaller unit than a bit unit of the output data from said input buffer;
• a zero detector for determining whether all values of said information of the smaller unit than the bit unit of said output data from said input buffer are 0 and generating a first or second control signal in accordance with the determined result to control the operation of said transformation/inverse transformation means;
• a switch for selecting the output of said transformation/inverse transformation means in response to said second control signal from said zero detector and said output data from said input buffer in response to said first control signal from said zero detector, respectively;
• an output buffer for sequentially storing output data from said switch;
• said transposition memory adapted for storing output data from said output buffer to transpose it on a two-dimensional plane and transferring the results of transformation/inverse transformation in one direction to said input buffer for the two-dimensional transformation/inverse transformation;
• and
• a clipping part for clipping the output data from said output buffer.

A method for one-dimensional transformation for digital image compression, comprising the steps of:

• a) determining whether all values of input data are 0;
• b) outputting said input data directly as the results of transformation without performing a one-dimensional transformation operation, if it is determined at said step a) that all the values of said input data are 0;
• and
• c) performing said one-dimensional transformation operation if it is determined at said step a) that all the values of said input data are not 0.

A method for one-dimensional inverse transformation for digital image compression, comprising the steps of:

• a) determining whether all values of input data are 0;
• b) outputting said input data directly as the results of inverse transformation without performing a one-dimensional inverse transformation operation, if it is determined at said step a) that all the values of said input data are 0;
• and
• c) performing said one-dimensional inverse transformation operation if it is determined at said step a) that all the values of said input data are not 0.