Image conversion apparatus for transforming compressed image data of different resolutions wherein side information is scaled

Claim 2

An image recompression method comprising: inverse quantizing a compressed image data, which has been previously quantized by a first quantization parameter, based on the first quantization parameter to generate a first inverse quantized coefficient; subtracting a compensation signal based on a previous image data from the first inverse quantized coefficient to produce a compensated inverse quantized coefficient, requantizing the compensated inverse quantized coefficient using a second quantization parameter to generate a requantized coefficient; reinverse quantizing the requantized coefficient using the second quantization parameter to generate a second inverse quantized coefficient; and adding to the second inverse quantized coefficient the compensation signal and further subtracting the first inverse quantized coefficient to generate a compensation signal of the next image data.

Claim 3

An image recompression method comprising: inverse quantizing a compressed image data, which has been previously quantized by a first quantization parameter, based on the first quantization parameter to generate a first inverse quantized coefficient; subtracting a compensation signal based on a previous image data from the first inverse quantized coefficient to produce a compensated inverse quantized coefficient, requantizing the compensated inverse quantized coefficient using a second quantization parameter to generate a requantized coefficient; reinverse quantizing the requantized coefficient using the second quantization parameter to generate a second inverse quantized coefficient; and subtracting the difference data from the second inverse quantized coefficient to generate a compensation signal of the next image data.

Claim 4

An image recompression method comprising: inverse quantizing a compressed image data, which has been previously quantized by a first quantization parameter, based on the first quantization parameter to generate a first inverse quantized coefficient; subtracting a compensation signal based on a previous image data from the first inverse quantized coefficient to produce a compensated inverse quantized coefficient, requantizing the compensated inverse quantized coefficient using a second quantization parameter to generate a requantized coefficient; reinverse quantizing the requantized coefficient using the second quantization parameter to generate a second inverse quantized coefficient; and subtracting the difference data from the second inverse quantized coefficient to generate a compensation signal of the next image data.

Claim 5

An image recompression method comprising: subtracting a compensation coefficient generated according to a previous image data from a first conversion coefficient block contained in a compressed orthogonal transform image data to generate a second conversion coefficient block; extracting a predetermined number of coefficients from the second conversion coefficient block to generate a third conversion coefficient block; and generating a difference coefficient block using the third conversion coefficient block and the first conversion coefficient block, wherein the difference coefficient is a compensation coefficient of the next image data.

Claim 6

An image recompression method comprising: subtracting a compensation coefficient generated according to a previous image data from a first conversion coefficient block contained in a compressed orthogonal transform image data to generate a second conversion coefficient block; extracting a predetermined number of coefficients from the second conversion coefficient block to generate a third conversion coefficient block; and generating a difference coefficient block using the third conversion coefficient block and the first conversion coefficient block, wherein the difference coefficient is a compensation coefficient of the next image data.

Claim 7

An image recompression method as claimed in claim 3 , further comprising: adding a compensation coefficient generated from the past image data to the third conversion coefficient block, before said generating of a difference coefficient block.

Claim 8

An image recompression apparatus comprising: a variable length decoder operable to decode from a coded image input data, a first quantization parameter, a compressed image data that has been previously quantized by the first quantization parameter, and other information data; a first inverse quantizer operable to inverse quantize the compressed image data based on the first quantization parameter to generate a first inverse quantized coefficient, a first subtractor operable to subtract a compensation signal based on a previous image data from the first inverse quantized coefficient to produce a compensated inverse quantized coefficient, a quantizer operable to requantize the compensated inverse quantized coefficient using a second quantization parameter to generate a requantized coefficient; a second inverse quantizer operable to reinverse quantize the requantized coefficient using the second quantization parameter to generate a second inverse quantized coefficient; an adder operable to add the compensation signal to the second inverse quantized coefficient to generate a sum data; a second subtractor operable to subtract the second inverse quantized coefficient from the sum data to generate a compensation signal of the next image data; a memory operable to store the compensation signal; a variable length coder operable to convert the second quantization parameter and the requantized coefficient to variable length code; a multiplexer operable to multiplex the variable length code and the other information data to generate a compressed coded image input data.

Claim 9

An image recompression apparatus comprising: a variable length decoder operable to decode from a coded image input data, a first quantization parameter, a compressed image data that has been previously quantized by the first quantization parameter, and other information data; a first inverse quantizer operable to inverse quantize the compressed image data based on the first quantization parameter to generate a first inverse quantized coefficient, a first subtractor operable to subtract a compensation signal based on a previous image data from the first inverse quantized coefficient to produce a compensated inverse quantized coefficient, a quantizer operable to requantize the compensated inverse quantized coefficient using a second quantization parameter to generate a requantized coefficient; a second inverse quantizer operable to reinverse quantize the requantized coefficient using the second quantization parameter to generate a second inverse quantized coefficient; an adder operable to add the compensation signal to the second inverse quantized coefficient to generate a sum data; a second subtractor operable to subtract the second inverse quantized coefficient from the sum data to generate a compensation signal of the next image data; a memory operable to store the compensation signal; a variable length coder operable to convert the second quantization parameter and the requantized coefficient to variable length code; a multiplexer operable to multiplex the variable length code and the other information data to generate a compressed coded image input data.

Claim 10

An image recompression apparatus according to claim 5 , wherein said memory comprises: an inverse orthogonal transform processor operable to apply an inverse orthogonal transform to the compensation signal which is in a form of a coefficient difference; a coefficient difference memory operable to store the coefficient difference; and an orthogonal transform processor operable to apply an orthogonal transform to the coefficient difference.

Claim 11

An image recompression apparatus according to claim 5 , further comprising: an inverse orthogonal transform processor, provided in association with said first inverse quantizer, operable to generate the first inverse quantized coefficient in an inverse orthogonal transformed format; an orthogonal transform processor, provided in association with said first subtractor, operable to generate the difference data in an orthogonal transformed format; a reinverse orthogonal transform processor, provided in association with said second inverse quantizer, operable to generate the second inverse quantized coefficient in an inverse orthogonal transformed format.

Claim 12

An image recompression apparatus according to claim 5 , further comprising a switch operable to selectively produce either one of the coded image input data and the compressed coded image input data, and a storage device operable to store the selected data.

Claim 13

An image recompression apparatus comprising: a variable length decoder operable to decode from a coded image input data, a first conversion coefficient block, and other information data; a first subtractor operable to subtract a compensation coefficient, based on a previous image data, from the first conversion coefficient block to generate a second conversion coefficient block; a selector operable to select a predetermined number of coefficients from the second conversion coefficient block to form a third conversion coefficient block; an adder operable to add the compensation coefficient to the third conversion coefficient block to generate a sum data; a second subtractor operable to subtract the first conversion coefficient block from the sum data to generate a compensation coefficient of the next image data; a memory operable to store the compensation coefficient; a variable length coder operable to convert the third conversion coefficient block to variable length code; and a multiplexer operable to multiplex the variable length code and the other information data to generate a compressed coded image input data.

Claim 14

An image recompression apparatus comprising: a variable length decoder operable to decode from a coded image input data, a first conversion coefficient block, and other information data; a first subtractor operable to subtract a compensation coefficient, based on a previous image data, from the first conversion coefficient block to generate a second conversion coefficient block; a selector operable to select a predetermined number of coefficients from the second conversion coefficient block to form a third conversion coefficient block; an adder operable to add the compensation coefficient to the third conversion coefficient block to generate a sum data; a second subtractor operable to subtract the first conversion coefficient block from the sum data to generate a compensation coefficient of the next image data; a memory operable to store the compensation coefficient; a variable length coder operable to convert the third conversion coefficient block to variable length code; and a multiplexer operable to multiplex the variable length code and the other information data to generate a compressed coded image input data.

Claim 15

An image recompression apparatus according to claim 9 , wherein said memory comprises: an inverse orthogonal transform processor operable to apply an inverse orthogonal transform to the compensation coefficient which is in a form of a coefficient difference; a coefficient difference memory operable to store the coefficient difference; and an orthogonal transform processor operable to apply an orthogonal transform to the coefficient difference.

Claim 16

An image recompression apparatus according to claim 9 , further comprising a switch operable to selectively produce either one of the coded image input data and the compressed coded image input data, and a storage device operable to store the selected data.