Adaptive perceptual mapping and signaling for video coding
A method is provided for encoding a digital video to improve perceptual quality. The method includes receiving a digital video at a video encoder, providing a perceptual quantizer function defined by PQ ( L ) = ( c 1 + c 2 L m 1 1 + c 3 L m 1 ) m 2 , wherein L is a luminance value, c 1 , c 2 , c 3 , and m 1 are parameters with fixed values, and m 2 is a parameter with a variable value, adapting the perceptual quantizer function by adjusting the value of the m 2 parameter based on different luminance value ranges found within a coding level of the digital video, encoding the digital video into a bitstream using, in part, the perceptual quantizer function, transmitting the bitstream to a decoder, and transmitting the value of the m 2 parameter to the decoder for each luminance value range in the coding level.
1. A method of encoding a digital video, comprising:
receiving a digital video at a video encoder;
providing a perceptual quantizer function as a mapping function at said video encoder, said perceptual quantizer function defined by
PQ
(
L
)
=
(
c
1
+
c
2
L
m
1
1
+
c
3
L
m
1
)
m
2
wherein L is a luminance value, c 1 , c 2 , c 3 , and m 1 are parameters with fixed values, and m 2 is a parameter with a variable value;
adapting said perceptual quantizer function at said video encoder by adjusting the value of said m 2 parameter based on different luminance value ranges found within a coding level of said digital video to provide a current m 2 parameter;
encoding said digital video into a bitstream with said video encoder using, in part, said perceptual quantizer function;
transmitting said bitstream to a decoder;
reversing a previously performed version of the perceptual quantizer function performed on a reference frame wherein the previously performed version provided a mapping of the reference frame using a previous value of said m 2 parameter determined for the reference frame, wherein the reference frame is a previously coded picture that is used to predict a current picture;
re-mapping the reference frame with the perceptual quantizer function using the current value of said m 2 parameter associated with the current picture to form a re-mapped reference frame; and
transmitting the current value of said m 2 parameter to said decoder along with the re-mapped reference frame for each luminance value range in said coding level for use in prediction of the perceptual quantization in coding the current picture.
2. A method of decoding a digital video signal, comprising:
receiving a bitstream at a video decoder;
providing a perceptual quantizer function as a mapping function at said video decoder, said perceptual quantizer function defined by
PQ
(
L
)
=
(
c
1
+
c
2
L
m
1
1
+
c
3
L
m
1
)
m
2
wherein L is a luminance value, c 1 , c 2 , c 3 , and m 1 are parameters with fixed values, and m 2 is a parameter with a variable value;
receiving a particular value for the m 2 parameter for each luminance value range in a coding level; and
decoding said digital video with said video decoder using, in part, said perceptual quantizer function with the received current value of the m 2 parameter used on a reference frame to decode a current frame of the video signal, wherein the value of said m 2 parameter is received in a supplemental enhancement information (SEI) message;
reversing a previously performed version of the perceptual quantizer function performed on a reference frame wherein the previously performed version provided a mapping of the reference frame using a previous value of said m 2 parameter received for the reference frame, wherein the reference frame is a previously coded picture that is used to predict a current picture;
re-mapping the reference frame with the perceptual quantizer function using the current value of said m 2 parameter associated with the current picture to form a re-mapped reference frame; and
decoding the current picture with reference to the re-mapped reference frame.