Fine granularity scalability encoding/decoding apparatus and method

A fine granularity scalability encoding apparatus, comprising:

• a first quantizer which quantizes a resulting DCT value from a motion-compensated image;
• a second quantizer which re-quantizes the value obtained by the first quantizer;
• an inverse-quantizer which inverse quantizes a value re-quantized by the second quantizer;
• re-inverse-quantizer which re-inversely quantizes the value inversely quantized by the inverse-quantizer;
• and
• a subtracter which obtains a difference between the value quantized by the first quantizer and a value equal to N times the value quantized by the second quantizer.

A fine granularity scalability decoding apparatus, comprising:

• a bit plane variable length decoding (VLD) unit which performs variable-length decoding of an enhancement layer bit stream by bit planes;
• an adding/subtracting unit which adds/subtracts a difference value between the variable length decoded value of each bit plane and an image reproduced in the base layer;
• an inverse-quantizer which inversely quantizes the added/subtracted value;
• an inverse discrete cosine transforming unit which restores an image transmitted from the enhancement layer by performing an inverse discrete cosine transforming (IDCT) on the inversely quantized value by block units;
• and
• a clipping unit which restores an enhanced image by clipping the inverse discrete cosine transformed image values in the range of 0~255.

A fine granularity scalability encoding method, comprising:

• quantizing a value obtained by performing a discrete cosine transforming on a motion-compensated image;
• re-quantizing the quantized value;
• inverse-quantizing the re-quantized value;
• obtaining a difference between a value of N times the re-quantized value and the inverse-quantized value;
• obtaining a difference between the first-quantized value and the inverse-quantized value;
• and
• subtracting output values obtained in the obtaining steps.

A fine granularity scalability encoding method, comprising

• quantizing a value obtained by performing a discrete cosine transforming on a motion-compensated image;
• re-quantizing the quantized value;
• inversely quantizing the re-quantized value;
• inversely quantizing the inversely quantized value;
• obtaining a difference between the first-quantized value and a value equal to N times the requantized value.

A fine granularity scalability decoding method comprising:

• variable-length decoding an enhancement layer bit stream by bit planes;
• adding/subtracting a difference value between the variable length decoded value of each bit plane and an image reproduced in a base layer;
• inversely quantizing the added/subtracted value;
• restoring an image transmitted from the enhancement layer by performing an inverse discrete cosine transforming (IDCT) on the inversely quantized value by block units;
• and
• restoring an enhanced image by clipping the inverse discrete cosine transformed image values in the range of 0~255.