DECODING DEVICE, CONTROL METHOD FOR A DECODING DEVICE, TRANSMISSION SYSTEM, AND COMPUTER-READABLE RECORDING MEDIUM HAVING A CONTROL PROGRAM RECORDED THEREON

• US 20120213289A1
• Filed: 06/23/2010
• Published: 08/23/2012
• Est. Priority Date: 11/17/2009
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Gohshi, Seiichi
• Granted Patent: US 8,824,825 B2
• Time in Patent Office: Days
• US Class Current: 375/240.16
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 5/75 Unsharp masking
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 5/208 for compensating for attenuation of high frequency components, e.g. crispening, aperture distortion correction

Abstract

A decoding device outputs an output signal by receiving, as an input, an encoded signal including a signal in which an original signal is encoded, the original signal being indicative of contents of at least one of image and audio, and the output signal being indicative of the contents. The decoding device includes a decoding process section that generates a decoded signal, and a nonlinear process section that generates a nonlinear process signal (i) in which positive and negative signs of a low-frequency-free signal are retained, which low-frequency-free signal is obtained by removing from the input signal at least a direct current of frequency components included in the decoded signal, and (ii) which broadly monotonically increases nonlinearly with respect to the low-frequency-free signal when values of the low-frequency-free signal are at least in the vicinity of 0. The nonlinear process signal is added to the decoded signal.

Claims

1. A decoding device that outputs an output signal by receiving, as an input, an encoded signal including a signal in which an original signal is encoded, the original signal being indicative of contents of at least one of image and audio, and the output signal being indicative of the contents, the decoding device comprising:

decoding means for decoding the encoded signal, to generate a decoded signal;

low-frequency component removing means for removing, from frequency components of the decoded signal, a low-frequency component at least including a direct current component, to generate a low-frequency-free signal;

nonlinear processing means for generating a nonlinear process signal (i) in which positive and negative signs of the low-frequency-free signal are retained and (ii) which broadly monotonically increases nonlinearly with respect to the low-frequency-free signal when values of the low-frequency-free signal are at least in the vicinity of 0; and

addition means for adding the nonlinear process signal to the decoded signal, to generate an addition signal,

the addition signal being outputted as the output signal.

2. The decoding device according to claim 1, wherein

the contents are constituted of a plurality of frames that are consecutive in terms of time, and

the encoded signal includes, in each frame, any one of a first signal or a second signal, the first signal being a signal in which the original signal is encoded and the second signal being a signal in which a part of frequency components included in the original signal is encoded,

the decoding means further (i) generating, as the decoded signal when the first signal is decoded, a signal in which the first signal is decoded, and (ii) generating, as the decoded signal when the second signal is decoded, a signal by adding (a) a signal of a decoded signal generated immediately before that has been subjected to motion compensation with use of motion vector information calculated in the encoding, the motion vector information being used for carrying out inter-frame motion compensation prediction, to (b) a signal in which the second signal is decoded.

3. The encoding device according to claim 1, further comprising:

signal interpolation means for interpolating the decoded signal.

4. The encoding device according to claim 1, wherein

the nonlinear process means includes:

even exponentiation operation means for generating an even exponentiation signal by raising the low-frequency-free signal to an even exponent not less than 2; and

sign changing means for generating the nonlinear process signal by reversing positive and negative signs of a part of the even exponentiation signal which part is different in sign from the low-frequency-free signal.

5. The encoding device according to claim 1, wherein

the nonlinear process means includes:

even exponentiation operation means for generating an even exponentiation signal by raising the low-frequency-free signal to an even exponent not less than 2;

differentiation means for generating a differential signal by differentiating the even exponentiation signal; and

sign changing means for generating the nonlinear process signal by reversing positive and negative signs of a part of the differential signal which part is different in sign from the low-frequency-free signal.

6. The encoding device according to claim 1, wherein

the nonlinear process means includes odd exponentiation operation means for generating the nonlinear process signal by raising the low-frequency-free signal to an odd exponent not less than 3.

7. The encoding device according to claim 1, wherein

the nonlinear processing means includes

square root operation means for generating a square root signal by multiplying (i) a square root of an absolute value of a value calculated by dividing the low-frequency-free signal by a possible maximum value of the low-frequency-free signal, by (ii) the maximum value;

and

sign changing means for generating the nonlinear process signal by reversing positive and negative signs of a part of the square root signal which part is different in sign from the low-frequency-free signal.

8. The encoding device according to claim 1, wherein

the nonlinear process means further includes amplitude adjustment means for adjusting an amplitude of the nonlinear process signal by multiplying the amplitude by a predetermined magnification value.

9. The encoding device according to claim 1, wherein

when the values of the low-frequency-free signal are around 0, the nonlinear process means generates the nonlinear process signal so that the nonlinear process signal has an absolute value larger than that of the low-frequency-free signal.

10. The encoding device according to claim 1, wherein the low-frequency component removing means is a high-pass filter having 3 or more taps.

11. The encoding device according to claim 1, wherein

the low-frequency component removing means further includes:

low-level signal removing means for changing, out of signal values of the low-frequency-free signal, signal values whose absolute values are lower than a predetermined lower limit to 0, and

high-level signal removing means for changing, out of the signal values of the low-frequency-free signal, signal values whose absolute values are higher than a predetermined upper limit in such a manner that the absolute values are not higher than the predetermined upper limit while maintaining signs of that signal values.

13. A transmission system comprising:

an encoding device as a sending device, the encoding device outputting the encoding signal including a signal in which the original signal is encoded; and

a decoding device as set forth in claim 1, as a receiving device.

14. A transmission system comprising:

an encoding device as a sending device, the encoding device including (i) frequency component extracting means for extracting, from the original signal, a part of frequency components included in the original signal, to generate a frequency component extraction signal and (ii) encoding means for (a) encoding the frequency component extraction signal and the original signal in such a manner that the encoding is carried out while switching over between the frequency component extraction signal and the original signal, and (b) making the signal thus encoded be included in the encoded signal; and

a decoding device as set forth in claim 2, as a receiving device.

15. The encoding device according to claim 14, wherein

the frequency component extracting means includes:

high-frequency component removing means for removing a high-frequency component from frequency components of the original signal, to generate a high-frequency-free signal;

harmonics generation means for generating harmonics of the high-frequency-free signal; and

subtraction means for subtracting the harmonics of the high-frequency-free signal from the original signal, to generate the frequency component extraction signal,

the harmonics generation means including;

second low-frequency component removing means for removing, from frequency components of the high-frequency-free signal, a low-frequency component at least including a direct current component, to generate a second low-frequency-free signal;

second nonlinear process means for generating a second nonlinear process signal (i) in which positive and negative signs of the second low-frequency-free signal are retained and (ii) which broadly monotonically increases nonlinearly with respect to the second low-frequency-free signal when values of the second low-frequency-free signal are at least in the vicinity of 0; and

second addition means for adding the second nonlinear process signal to the high-frequency-free signal, to generate the harmonics.

16. A computer-readable recording medium in which a control program is recorded, the control program causing a computer included in a decoding device as set forth in claim 1 to operate.

12. A method of controlling a decoding device that outputs an output signal by receiving, as an input, an encoded signal including a signal in which an original signal is encoded, the original signal being indicative of contents of at least one of image and audio, the method comprising:

decoding the encoded signal, to generate a decoded signal;

removing, from frequency components of the decoded signal, a low-frequency component at least including a direct current component, to generate a low-frequency-free signal;

generating a nonlinear process signal (i) in which positive and negative signs of the low-frequency-free signal are retained and (ii) which broadly monotonically increases nonlinearly with respect to the low-frequency-free signal when values of the low-frequency-free signal are at least in the vicinity of 0; and

adding the nonlinear process signal to the decoded signal, to generate an addition signal,

the addition signal being outputted as the output signal.