OBJECTIVE PERCEPTUAL VIDEO QUALITY EVALUATION APPARATUS

• US 20080025400A1
• Filed: 07/30/2007
• Published: 01/31/2008
• Est. Priority Date: 07/31/2006
• Status: Active Grant

• Current Assignee: KDDI Corporation
• Original Assignee: KDDI Corporation
• Inventors: SUGIMOTO, Osamu, SAKAZAWA, Shigeyuki, KOIKE, Atsushi
• Granted Patent: US 8,457,204 B2
• Time in Patent Office: Days
• US Class Current: 375/240.16
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/587 involving temporal sub-sampling or interpolation, e.g. decimation or subsequent interpolation of pictures in a video sequence
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A feature amount extracting unit extracts a block distortion degree of an evaluated video y relative to an original video x, a PSNR overall temporal fluctuation degree, and a PSNR local temporal fluctuation degree as feature amounts. A weighted sum calculating unit calculates a weighted sum of these feature amounts, and calculates an objective video quality index. Frame rate detecting unit detects frame rate of the evaluated video y. A correcting unit corrects the objective video quality index based on the frame rate detected by the frame rate detecting unit. An objective evaluation index-subjective video quality mapping unit applies the corrected objective video quality index Q_obj to a correlation between an objective video quality index and a subjective video quality given in advance, thereby deriving a subjective video quality estimated value DMOS.

Claims

1. An objective perceptual video quality evaluation apparatus for estimating a subjective video quality by analyzing two types of video signals of an original video and an evaluated video, comprising:

a feature amount extracting unit for extracting a block distortion degree of the evaluated video relative to the original video, a PSNR overall temporal fluctuation degree for frames in a sequence, and a PSNR local temporal fluctuation degree for each of the frames as feature amounts;

an objective video quality index calculating unit for calculating a weighted sum of the block distortion degree, the PSNR overall temporal fluctuation degree, and the PSNR local temporal fluctuation degree, and calculating an objective video quality index;

frame rate detecting unit for detecting frame rate of the evaluated video;

a correcting unit for correcting the objective video quality index calculated by the objective video quality index calculating unit based on the frame rate detected by the frame rate detecting unit; and

a subjective video quality estimated value deriving unit for deriving a subjective video quality estimated value by applying the objective video quality index corrected by the correcting unit to a correlation between the subjective video quality index and the objective video quality given in advance.

2. The objective perceptual video quality evaluation apparatus according to claim 1,

the objective video quality index calculating unit

calculates an intra-frame average value of a DC difference among a plurality of pixel blocks of each of the original video and the evaluated video and pixel blocks adjacent to the pixel block of interest,

calculates an intra-sequence maximum difference between the intra-frame average value of the DC difference for the original video and the intra-frame average value of the DC difference for the evaluated video as a maximum value of the DC difference, and

calculates an intra-sequence minimum difference between the intra-frame average value of the DC difference for the original video and the intra-frame average value of the DC difference for the evaluated video as a minimum value of the DC difference, and

obtains a difference between the maximum value of the DC difference and the minimum value of the DC difference as the block distortion degree.

3. The objective perceptual video quality evaluation apparatus according to claim 1,

the PSNR overall temporal fluctuation degree is derived based on a ratio of an absolute value of a difference between a maximum value and an average value of an MSE of each of the frames in the sequence to an absolute value of a difference between a minimum value and the average value of the MSE of each of the frames in the sequence.

4. The objective perceptual video quality evaluation apparatus according to claim 3,

the ratio of the absolute value of the difference between the maximum value and the average value of the MSE of each of the frames in the sequence to the absolute value of the difference between the minimum value and the average value of the MSE of each of the frames in the sequence is multiplied by a scaling function for changing a value according to an average value of the MSE in the sequence

5. The objective perceptual video quality evaluation apparatus according to claim 1,

the PSNR local temporal fluctuation degree is an intra-sequence maximum value of a PSNR value of the frame of interest and PSNR values of the adjacent frames before and after the frame of interest.

6. The objective perceptual video quality evaluation apparatus according to claim 5,

the PSNR local temporal fluctuation degree is obtained by multiplying the intra-sequence maximum value of the PSNR difference between the adjacent frames by a scaling function for changing a value according to the MSE value of the frame of interest.