Decoding device with nonlinear process section, control method for the decoding device, transmission system, and computer-readable recording medium having a control program recorded thereon

• US 8,824,825 B2
• Filed: 06/23/2010
• Issued: 09/02/2014
• Est. Priority Date: 11/17/2009
• Status: Expired due to Fees

• 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
• Primary Examiner(s): Mehta, Bhavesh
• Assistant Examiner(s): Niu, Feng
• Application Number:
  US13/504,351
• Publication Number:
  US 20120213289A1
• Time in Patent Office: 1,532 Days
• Field of Search: None
• US Class Current: 382/263
• 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

Disclosed is a decoding device (300a) 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, which decoding device includes a decoding process section (310) that generates a decoded signal be decoding the encoded signal, and a nonlinear process section (102) 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, to generate the output signal.

Claims

1. A transmission system comprising:

a decoding device as a receiving device, the 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 including,

a decoder configured to decoding the encoded signal, to generate a decoded signal,

an up sampler configured to up-convert the decoded signal,

a low-frequency component removing filter configured to generate a low-frequency-free signal by removing, a low-frequency component including at least a direct current component from the up-converted decoded signal,

a nonlinear processor configured to generate a nonlinear process signal (i) in which positive and negative signs of the low-frequency-free signal are retained and (ii) which monotonically increases nonlinearly based on the low-frequency-free signal when values of the low-frequency-free signal are at least in the vicinity of 0, and

an adder configured to add the nonlinear process signal to the up-converted decoded signal, to generate an addition signal,

the addition signal being the output signal, the contents are constituted of a plurality of frames that are consecutive in terms of time,

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, and

the decoder is configured to further (i) generate, as the decoded signal when the first signal is decoded, the decoded first signal, and (ii) generate the decoded signal by adding (a) a signal of a subsequent 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, when the second signal is decoded; and

an encoding device as a sending device, the encoding device including (i) a frequency component extracting filter configured to extract, from the original signal, a part of frequency components included in the original signal, to generate a frequency component extraction signal and (ii) an encoder configured to (a) encode 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) make the signal thus encoded be included in the encoded signal.

2. The encoding device according to claim 1, wherein

the frequency component extracting filter includes,

a high-frequency component removing filter configured to remove a high-frequency component from the original signal to generate a high-frequency-free signal;

a harmonics generator configured to generate harmonics of the high-frequency-free signal; and

a subtractor configured to subtract the harmonics of the high-frequency-free signal from the original signal, to generate the frequency component extraction signal, and

the harmonics generator including,

a second low-frequency component removing filter configured to remove a low-frequency component at least including a direct current component from the high-frequency-free signal, to generate a second low-frequency-free signal;

a second nonlinear processor configured to generate a second nonlinear process signal (i) in which positive and negative signs of the second low-frequency-free signal are retained and (ii) which monotonically increases nonlinearly based on the second low-frequency-free signal when values of the second low-frequency-free signal are at least in the vicinity of 0; and

a second adder configured to add the second nonlinear process signal to the high-frequency-free signal, to generate the harmonics.

3. The decoding device according to claim 1, wherein

the nonlinear processor includes:

an even exponentiation operator configured to generate an even exponentiation signal by raising the low-frequency-free signal to an even exponent not less than 2; and

a sign changer configured to generate the nonlinear process signal by reversing a sign of a part of the even exponentiation signal which is different from a sign of the low-frequency-free signal.

4. The decoding device according to claim 1, wherein

the nonlinear processor includes:

an even exponentiation operator configured to generate an even exponentiation signal by raising the low-frequency-free signal to an even exponent not less than 2;

a differentiator configured to generate a differential signal by differentiating the even exponentiation signal; and

a sign changer configured to generate the nonlinear process signal by reversing a sign of a part of the differential signal which is different in sign from the low-frequency-free signal.

5. The decoding device according to claim 1, wherein

the nonlinear processor includes odd an exponentiation operator configured to generate the nonlinear process signal by raising the low-frequency-free signal to an odd exponent not less than 3.

6. The decoding device according to claim 1, wherein

the nonlinear processor includes:

a square root operator configured to generate 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 possible maximum value; and

a sign changer configured to generate the nonlinear process signal by reversing a sign of a part of the square root signal which is different from a sign of the low-frequency-free signal.

7. The decoding device according to claim 1, wherein

the nonlinear processor further includes an amplitude adjuster configured to adjust an amplitude of the nonlinear process signal by multiplying the amplitude by a magnification value.

8. The decoding device according to claim 1, wherein

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

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

10. The decoding device according to claim 1, wherein

the low-frequency component removing filter further includes:

a low-level signal removing filter configured to change first signal values of the low-frequency-free signal whose absolute values are lower than a lower limit to 0; and

a high-level signal removing filter configured to change second signal values of the low-frequency-free signal whose absolute values are higher than a upper limit in such a manner that the absolute values of the second signal values of the low-frequency-free signal are not higher than the upper limit while maintaining signs of the second signal values.