Picture quality monitoring apparatus

Abstract

Picture having a band of 6 MHz is distributed to the set-top box (STB) 14 via the compression encoder 11, the distribution server 12, and the network 13. The low-pass filter 151 in the picture quality monitoring apparatus 15 removes high-frequency components of an inputted digital signal and inputs luminance signal, the band of which is limited to 4 MHz, into the PSNR calculator 153. The Y/C separator 152 separates a luminance signal from NTSC analog composite signal, which are sent out from the set-top box 14. The separated luminance signal has a band of 4 MHz. The PSNR calculator 153 calculates PSNR between the luminance signal from the low-pass filter 151 and the luminance signal from the Y/C separator 152.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the first embodiment according to the present invention;

FIG. 2 is a block diagram showing a detailed example of a set-top box;

FIG. 3 is a block diagram showing the second embodiment according to the present invention;

FIG. 4 is a block diagram showing a detailed example of a characteristic amount extracting means; and

FIG. 5 is a block diagram showing another example of the characteristic amount extracting means.

Claims

1. A picture quality monitoring apparatus for monitoring a picture quality degradation between an original picture and a processed picture whose band is limited by processing the original, comprising: a horizontal low-pass filter, applied to at least the original picture, for matching the bands of the original picture and the processed picture; anda comparing means for comparing the picture qualities of the original picture and the processed picture, the bands of which are matched by the horizontal low-pass filter.

2. The picture quality monitoring apparatus according to claim 1, wherein the original picture is of a digital signal and the processed picture is of an analog signal.

3. The picture quality monitoring apparatus according to claim 1, wherein the original picture is of a digital component signal, and the processed picture is of an analog composite signal.

4. A picture quality monitoring apparatus for monitoring a picture quality degradation between pictures at two or more points on a transmission link that includes a plurality of transmission apparatus in tandem, comprising: picture extracting means for extracting pictures at two or more points on a transmission link;a horizontal low-pass filter, applied to at least one picture of the pictures, for matching the bands of the respective pictures extracted by the picture extracting means;characteristic extracting means for extracting picture quality characteristic amounts of the respective pictures whose bands are matched by the horizontal low-pass filter; andtransmitting means for transmitting the picture quality characteristic amounts extracted by the characteristic amount extracting means to a central monitoring room;wherein the respective picture quality characteristic amounts are compared with each other in the central monitoring room, and the picture quality degradation of the transmitted picture is monitored.

5. The picture quality monitoring apparatus according to claim 4, wherein the characteristic amount extracting means includes an orthogonal transforming means for orthogonally transforming the picture whose band is matched by the horizontal low-pass filter and an orthogonal transformed coefficients extracting means for extracting orthogonal transformed coefficient outputted from the orthogonal transforming means as the picture quality characteristic amount.

6. The picture quality monitoring apparatus according to claim 4, wherein the characteristic amount extracting means includes a calculating means for applying PN-series multiplication and orthogonal transformation to the picture whose band is matched by the horizontal low-pass filter and a extracting means for extracting orthogonal transformation coefficient outputted from the calculating means as the picture quality characteristic amount.

7. The picture quality monitoring apparatus according to any one of claims 4 through 6, wherein at least one picture to which the horizontal low-pass filter is applied is of a digital signal and the other picture is of an analog signal.

8. The picture quality monitoring apparatus according to any one of claims 4 through 6, wherein at least one picture to which the horizontal low-pass filter is applied is of a digital component signal and the other picture is of an analog composite signal.