Coding apparatus and method, decoding apparatus and method, image processing system, image processing method, recording medium, and program

A decoding method comprising the steps of:

• inputting quantized data in which input image data is quantized;
• and
• decoding by dequantizing the quantized data that is input by the input step and by converting a dequantized value obtained as a result of the quantization into a value in the vicinity of the boundary of a quantization threshold value within a range corresponding to the dequantized value when the quantization is performed.

A recording medium having recorded thereon a program for enabling a computer to execute a process for decoding quantized data, the program comprising the steps of:

• inputting quantized data in which input image data is quantized;
• and
• decoding by dequantizing the quantized data that is input by the input step and by converting a dequantized value obtained as a result of the quantization into a value in the vicinity of the boundary of a quantization threshold value within a range corresponding to the dequantized value when the quantization is performed.

An image processing method for use with an image processing system including a coding device configured to code input image data, and a decoding device configured to decode the coded input image data, wherein, if coding and decoding are repeated on the input image data, the image quality of an image corresponding to the input image data is deteriorated, the image processing method comprising the step of:

• quantizing the input image data.

An image processing method for use with an image processing system including a coding device configured to code input image data, and a decoding device configured to decode the coded input image data, wherein, if coding and decoding are repeated on the input image data, the image quality of an image corresponding to the input image data is deteriorated, the image processing method comprising the steps of:

• inputting quantized data in which input image data is quantized;
• and
• decoding by dequantizing the quantized data that is input by the input step and by converting a dequantized value obtained as a result of the quantization into a value in the vicinity of the boundary of a quantization threshold value within a range corresponding to the dequantized value when the quantization is performed.

A decoding apparatus comprising:

• input means for inputting quantized data in which input image data is quantized;
• and
• decoding means for dequantizing the quantized data that is input by the input means and for converting a dequantized value obtained as a result of the quantization into a value in the vicinity of the boundary of a quantization threshold value within a range corresponding to the dequantized value when the quantization is performed.