JP2003179951A - Image quality evaluator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image quality evaluation suitable as a device for evaluating an image quality when an interlace scanning signal is converted to a sequential scanning signal. <P>SOLUTION: The device is provided with an interlace signal converting means A52 for thinning the even-numbered lines of an inputted sequential scanning signal 58 and outputting odd-numbered lines, an interlace signal converting means B53 for thinning the odd-numbered lines of the inputted sequential scanning signal and outputting even-numbered lines, an IP converter 54 as an object to evaluate the image quality to input the output signal from the interlace signal converting means B, and an interlace signal converting means C55 for inputting an output signal from the IP converter, thinning even-numbered lines and outputting only odd-numbered lines. By comparing an output signal 62 of the interlace signal converting means A with an output signal 61 of the interlace signal converting means C, the deterioration of the image quality caused by the IP converter is evaluated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image quality evaluation device for a television signal processing device.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 8-205156 is known as a prior art of an image quality evaluation apparatus for reproduced images. FIG. 5 shows the configuration of the image quality evaluation device in the above publication. Figure 5
In the above, 2 is a system to be evaluated which is a device under test which is a target of image quality evaluation, and 3 is a system which evaluates image quality of the device under test.

The synchronization control unit 14 in the evaluation system 3
Controls the delay amount of the delay unit 15 so that the original image data input from the video source 1 and the reproduced image data compressed and reproduced by the evaluation target system 2 can be synchronized.

The first orthogonal transform calculation unit 17 converts the reproduced image into
Further, the second orthogonal transformation calculation unit 21 orthogonally transforms the original image,
The subtraction unit 19 obtains the error value of the same coefficient in the same block. A weighted signal to noise ratio (WSNR) calculation unit 22 weights the error by a position of a coefficient of the orthogonally transformed data and a weighting function that changes depending on the magnitude of the AC power in the block after the orthogonal transformation in the original image. Then, the average weighted S / N ratio is calculated for each frame or for each of a plurality of frames.

Finally, the subjective evaluation value calculation unit 23 calculates a subjective evaluation value (deterioration degree) based on the average weighted S / N ratio. In this way, the reproduced image data can be evaluated without manpower. The functions and operations of the block configuration shown in FIG. 5 are as described in detail in the above-mentioned publication.

[0006]

At present, there is a demand for an apparatus for evaluating the image quality when the interlaced scanning signal (I) is converted into the progressive scanning signal (P). That is, there is a demand for an evaluation device that evaluates the image quality of the IP conversion device that is the evaluation target.

However, the above-mentioned Japanese Unexamined Patent Publication No. 8-205156.
The conventional image quality evaluation device disclosed in Japanese Patent Publication is an image quality evaluation device devised mainly for comparing and evaluating an original image and a compressed and reproduced image. It cannot be applied as it is as an apparatus for evaluating the image quality when converted into a scanning signal, and cannot be said to be suitable.

Therefore, an object of the present invention is to provide an image quality evaluation apparatus suitable as an apparatus for evaluating the image quality when an interlaced scanning signal is converted into a progressive scanning signal.

[0009]

In order to solve the above problems, the present invention adopts the following configurations. An interlace signal conversion means A for thinning out even lines of an input progressive scanning signal to output an odd line, and an interlace signal conversion means B for thinning out odd lines of an input progressive scanning signal and outputting an even line, An IP converter to which an output signal from the interlace signal converting means B is input and which is an object of image quality evaluation, and an interlace which inputs the output signal from the IP converter and thins out even lines to output only odd lines. Signal conversion means C, and comparing the output signal of the interlaced signal conversion means A with the output signal of the interlaced signal conversion means C to obtain the I
An image quality evaluation device for evaluating image quality deterioration due to a P conversion device.

Further, an interlace signal converting means A for thinning out even lines of the input progressive scanning signal and outputting odd lines, and an interlace signal converting for thinning out the odd lines of the input progressive scanning signal and outputting even lines. A conversion unit B, an IP conversion device as an image quality evaluation target to which an output signal from the interlaced signal conversion unit A is input, and an output signal from the IP conversion device are input to thin out odd lines to obtain only even lines. And an output signal of the interlaced signal conversion unit C by comparing the output signal of the interlaced signal conversion unit B with the output signal of the interlaced signal conversion unit C. Image quality evaluation device for evaluation.

Further, in the image quality evaluation device, the evaluation by comparison between the output signals of the interlaced signal conversion means is based on an error signal obtained by subtracting each output signal after orthogonal conversion.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An image quality evaluation apparatus according to an embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of an image quality evaluation device according to an embodiment of the present invention.

In FIG. 1, a progressive camera 51
The scanning lines in the sequential scanning signal input from the etc. are arranged in sequence as indicated by reference numeral 58 in FIG. The interlace signal conversion means A52 thins out the input signals of the even-numbered lines (or odd-numbered lines) of the input progressive scanning signals to perform interlaced signal conversion. In the interlaced signal conversion means B53, the input signal on the line opposite to that of the interlaced signal conversion means A52 is thinned out (an odd line if A is an even line, an even line if A is an odd line), Perform race signal conversion.

In the IP converter 54 of the device under test whose image quality is to be evaluated, the interlaced signal converter B5 is used.
The interlaced signals decimated in 3 are converted into progressive scanning signals. The interlaced signal conversion means C55 thins out the input signal on the line opposite to that of the interlaced signal conversion means B53 to perform interlaced signal conversion.

In the image quality evaluation apparatus according to this embodiment, the IP conversion apparatus 54 is constructed by comparing the output signal 62 of the interlaced signal conversion means A52 and the output signal 61 of the interlaced signal conversion means C55 by the image quality evaluation section 56. The deterioration of the image quality due to is evaluated. At this time, in each output of the interlaced signal conversion means A and the interlaced signal conversion means C, the IP conversion device 54 is provided on the conversion means C side.
Since the output from the conversion means C becomes slower due to the two interlaced signal conversions, a delay device 57 is provided between the interlaced signal conversion means A and the image quality evaluation section 56 for synchronization.

Further, in FIG. 1, the IP converter of the image quality evaluation object is arranged on the downstream side of the interlace signal converting means B, but not limited to this, it is arranged on the downstream side of the interlace signal converting means A. In this case, the interlaced signal converting means C (changing the thinning line) is arranged on the IP converter side.

A scan conversion device for converting from interlaced scanning to progressive scanning as shown in the IP conversion device 54 of FIG.
As shown in FIG. 2, the delay memories 81 and 8 connected in cascade are provided.
2, 83, coefficient units 88 and 89, and motion detection circuit 90
And a time axis compression circuit 91, which converts the interlaced scanning system signal supplied to the input terminal IN into a progressive scanning system television signal having a double line density and outputs the output terminal OU.
Output to T.

In FIG. 2, a 262 line delay memory 8
Paying attention to the pixel signal a appearing at the output terminal of 1 and assuming that this is on the nth line of the current field, as shown in FIG. 3, it appears at the output terminal of the 1-line delay memory 82 of the next stage. The middle pixel signal b exists on the (n-1) th line one line before in the current field of the interlaced scanning method.

Further, the pixel signal c appearing at the output terminal of the 262 line delay memory 83 and the 262 line delay memory 8
The pixel signal d appearing at the input terminal of 1 is a pixel on the n'th line that appears one field before and one field after the current field including the pixel signals a and b, as shown in FIG. It is a signal, which appears in the middle of the nth line and the (n-1) th line of the current field.

That is, if the current field containing the pixel signals a and b is an odd field of the interlaced scanning method,
The field containing the pixel signal c is an even field one field before, and the field containing the pixel signal d is an even field one field after. The adder 84 outputs an interpolation line signal (a + b) generated based on the correlation between adjacent lines, and the adder 85 outputs an interpolation line signal (c + d) generated based on the correlation between adjacent frames.
Is output. The respective interpolating line signals are combined by the combining circuit including the adder 86 and the coefficient units 88 and 89 at the changeable combining ratios k and (1-k), and the following interpolating line signal e is generated.

E = {k (a + b) / 2} + {(1-k)
(C + d) / 2} The motion detection circuit 90 detects the motion in the display screen from the inter-frame difference signal output from the subtractor 87, and controls the coefficient values of the coefficient units 88 and 89 in accordance with the detected motion. By doing so, the composition ratios k and (1-k) are dynamically controlled. If there is no motion, k in the above equation is set to 0, and the interpolation line signal e is composed of only the component (c + d) / 2 generated based on the correlation between adjacent frames. If there is a large motion, k in the above equation is set to 1, and the interpolation line signal e is composed of only the component (a + b) / 2 generated based on the correlation between adjacent lines in the field.

The above is a typical configuration example of the IP conversion, but the performance of the IP conversion is determined by the algorithm. Since the algorithm difference appears in the generated interpolation line, a method of comparing this interpolation line with the original image is effective for measuring the IP conversion performance. Therefore, in the present invention, when the interlace signal converting means B outputs the even lines of the scanning lines, the interlace signal converting means A and C output the odd lines and B outputs the odd lines of the scanning lines. At this time, an even line is output in each of A and C so that the interpolation line is compared with the original image (see the scanning line mode shown in FIG. 1).

Next, FIG. 4 is a diagram showing a specific configuration of the image quality evaluation unit 56 (see FIG. 1) in the image quality evaluation apparatus according to this embodiment. In FIG. 4, the evaluation signal input is a signal that has passed through the IP conversion device 54 which is the object to be evaluated, and the reference signal input is a comparison reference signal corresponding to reference numeral 62 with reference to FIG.

The first orthogonal transformation calculation unit 17 inputs the evaluation images sequentially scanned by the IP conversion device 54, which is the evaluation object, input from the input unit 12, and the second orthogonal transformation calculation unit 21 inputs. The reference image input from the unit 11 is orthogonally transformed, and the subtraction unit 19 obtains an error value of a homogenous coefficient (parameter associated with orthogonal transformation) in the same block.

Here, the image evaluation section is composed of the components shown in FIG. 4, and the statistic calculation section 18 obtains the AC power average value of one frame from the orthogonally transformed evaluation signal input. , The WSNR calculation unit 22 weights the error with a weighting function that varies depending on the position of the coefficient of the orthogonally transformed data and the magnitude of the AC power in the block after the orthogonal transformation in the original image, and then averages for each frame. Calculate the weighted S / N ratio. Finally, the subjective evaluation calculation unit 23 uses the average weighted S
The subjective evaluation value (deterioration degree) is calculated based on the / N ratio. The table unit 20 creates a correspondence relationship between the statistic obtained by the statistic calculation unit 18 and the WSNR obtained by the WSNR calculation unit 22 as a table.

[0026]

According to the present invention, it is possible to evaluate the image quality of an IP conversion device by using an inexpensive image quality evaluation device compatible with interlace.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an image quality evaluation device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a specific configuration of an IP conversion device that converts an interlaced signal into a progressive scanning signal.

FIG. 3 is a conceptual diagram showing an aspect of generating an interpolation line in the IP conversion device in FIG.

FIG. 4 is a diagram showing a specific configuration of an image quality evaluation unit in the image quality evaluation apparatus according to the present embodiment.

FIG. 5 is a diagram showing a conventional image quality evaluation device.

[Explanation of symbols]

1 Image source 2 Target system 11,12 Input section 13 Synchronization marker addition unit 14 Synchronization control unit 15 Delay section 16 Output section 17,21 Orthogonal transformation unit 19 Subtraction unit 20 table section 22 WSNR calculator 23 Subjective evaluation value calculator 51 progressive camera 52 Interlaced signal conversion A 53 Interlaced signal conversion B 54 IP converter 55 Interlaced signal conversion C 56 Image quality evaluation section

Continued front page    (72) Inventor Yuichi Kubo             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Taiji Nishizawa             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F-term (reference) 5C061 BB07 CC05 CC09                 5C063 BA04 BA09 BA10 CA01 CA05                       CA36 CA40

Claims (3)

[Claims] 1. An interlaced signal conversion means A for thinning out even lines of an input progressive scanning signal to output an odd line, and an interlaced signal for thinning out an odd line of an input progressive scanning signal to output an even line. A conversion unit B, an IP conversion device to which an output signal from the interlaced signal conversion unit B is input, which is an image quality evaluation target, and an output signal from the IP conversion device is input to thin out even lines to generate only odd lines. And an output signal of the interlaced signal conversion unit C by comparing the output signal of the interlaced signal conversion unit A with the output signal of the interlaced signal conversion unit C. An image quality evaluation device characterized by evaluation. 2. An interlace signal converting means A for thinning out even lines of an input progressive scanning signal and outputting an odd line, and an interlace signal converting unit for thinning out odd lines of an input progressive scanning signal and outputting an even line. A conversion unit B, an IP conversion device as an image quality evaluation target to which the output signal from the interlaced signal conversion unit A is input, and an output signal from the IP conversion device to which odd lines are thinned and only even lines are input. And an output signal of the interlaced signal conversion unit C by comparing the output signal of the interlaced signal conversion unit B with the output signal of the interlaced signal conversion unit C. An image quality evaluation device characterized by evaluation. 3. The image quality evaluation apparatus according to claim 1, wherein the evaluation by comparing the output signals of the interlaced signal conversion means is based on an error signal obtained by subtracting each output signal after orthogonal conversion. An image quality evaluation device characterized by.