APPARATUS AND METHOD FOR CODING/DECODING IMAGE SELECTIVELY USING DISCRETE COSINE/SINE TRANSFORM
Disclosed is a data transmission system that transmits data by using a relay. The relay selects a transmission terminal from among a plurality of terminals accessing a base station. A base station transmits base station data to the relay during a first time slot, and the transmission terminal transmits terminal data to the relay. The relay transmits terminal data to the base station during a second time slot, and transmits base station data to the transmission terminal.
1 . An image decoding apparatus comprising:
a memory; and
at least one processor connected to the memory, the at least one processor configured to:
determine a set of scaling factors for inverse-quantizing transform coefficients of a current block based on a size of the current block;
inverse-quantize the transform coefficients of the current block based on the set of scaling factors; and
generate a decoded image based on the inverse-quantized transform coefficients,
wherein the set of scaling factors is determined by selectively using one of a first predefined table from which one or more first candidate tables for a 4×4 block are derivable, each of the one or more first candidate tables for the 4×4 block specifying sixteen explicit integer values mapping one-to-one for sixteen locations in the 4×4 block and a second predefined table from which one or more second candidate tables for an 8×8 block are derivable, each of the one or more second candidate tables for the 8×8 block specifying sixty four explicit integer values mapping one-to-one for sixty four locations in the 8×8 block according to the size of the current block, each of the first candidate tables comprises ‘n’ distinct values, ‘n’ being smaller than 16, each of the second candidate tables comprises ‘m’ distinct values, ‘m’ being smaller than 64, and ‘n’ being smaller than ‘m’.
2 . The apparatus of claim 1 , wherein the at least one processor is further configured to:
generate a prediction image with respect to the transform coefficients based on a reference image,
wherein the decoded image is generated based on the prediction image.
3 . An image encoding apparatus comprising:
a memory; and
at least one processor connected to the memory, the at least one processor configured to:
inverse-quantize transform coefficients of a current block based on a set of scaling factors determined based on a size of the current block; and
generate a decoded image based on the inverse-quantized transform coefficients,
wherein the set of scaling factors is determined by selectively using one of a first predefined table from which one or more first candidate tables for a 4×4 block are derivable, each of the one or more first candidate tables for the 4×4 block specifying sixteen explicit integer values mapping one-to-one for sixteen locations in the 4×4 block and a second predefined table from which one or more second candidate tables for an 8×8 block are derivable, each of the one or more second candidate tables for the 8×8 block specifying sixty four explicit integer values mapping one-to-one for sixty four locations in the 8×8 block according to the size of the current block, each of the first candidate tables comprises ‘n’ distinct values, ‘n’ being smaller than 16, each of the second candidate tables comprises ‘m’ distinct values, ‘m’ being smaller than 64, and ‘n’ being smaller than ‘m’.
4 . An apparatus for transmitting a bitstream, the apparatus comprising:
at least one processor configured to obtain the bitstream; and
a transmitter configured to transmit the bitstream generated by an image encoding method, the image encoding method comprising:
inverse-quantizing transform coefficients of a current block based on a set of scaling factors determined based on a size of the current block; and
generating a decoded image based on the inverse-quantized transform coefficients,
wherein the set of scaling factors is determined by selectively using one of a first predefined table from which one or more first candidate tables for a 4×4 block are derivable, each of the one or more first candidate tables for the 4×4 block specifying sixteen explicit integer values mapping one-to-one for sixteen locations in the 4×4 block and a second predefined table from which one or more second candidate tables for an 8×8 block are derivable, each of the one or more second candidate tables for the 8×8 block specifying sixty four explicit integer values mapping one-to-one for sixty four locations in the 8×8 block according to the size of the current block, each of the first candidate tables comprises ‘n’ distinct values, ‘n’ being smaller than 16, each of the second candidate tables comprises ‘m’ distinct values, ‘m’ being smaller than 64, and ‘n’ being smaller than ‘m’.
5 . A non-transitory computer-readable medium recording a bitstream generated by an image encoding apparatus, wherein the image encoding apparatus comprising:
a memory; and
at least one processor connected to the memory, the at least one processor configured to:
inverse-quantize transform coefficients of a current block based on a set of scaling factors determined based on a size of the current block; and
generate a decoded image based on the inverse-quantized transform coefficients,
wherein the set of scaling factors is determined by selectively using one of a first predefined table from which one or more first candidate tables for a 4×4 block are derivable, each of the one or more first candidate tables for the 4×4 block specifying sixteen explicit integer values mapping one-to-one for sixteen locations in the 4×4 block and a second predefined table from which one or more second candidate tables for an 8×8 block are derivable, each of the one or more second candidate tables for the 8×8 block specifying sixty four explicit integer values mapping one-to-one for sixty four locations in the 8×8 block according to the size of the current block, each of the first candidate tables comprises ‘n’ distinct values, ‘n’ being smaller than 16, each of the second candidate tables comprises ‘m’ distinct values, ‘m’ being smaller than 64, and ‘n’ being smaller than ‘m’.