JPH0614336A - High-vision image processor - Google Patents

Abstract

PURPOSE:To execute proper high frequency compensation matched with subjective evaluation in accordance with the movement of an image. CONSTITUTION:An aperture matrix unit 12 is connected to a muse decoder 1 for decoding a high-vision signal whose band is compressed based upon a prescribed encoding system and the high frequency compensation of a rapid image is executed in a low spatial frequency band, so that picture formation based on contract prior to resolution is executed in a rapid image and picture formation based on resolution prior to contract is executed in a slow image to sufficiently display excellent image expressing capacity originally included in a high-vision image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-definition image processing apparatus for performing appropriate high frequency compensation in accordance with subjective evaluation according to the movement of an image.

[0002]

2. Description of the Related Art A band compression method considered for transmitting a high-definition signal in a band of one channel of satellite broadcasting is a MUSE method, which is a studio standard 30.
High-definition signals with a band of MHz of 8.1 MHz
Band transmission is performed until the satellite is relayed by FM band-compressing the obtained muse / high-definition signal. The muse decoder 1 shown in FIG. 6 is used for a high-definition image receiver that receives high-definition signals sent from broadcasting satellites, and by performing signal processing that is the reverse of the encoding method used for band compression, Decode. That is, the muse signal FM-detected by the high-definition BS tuner (not shown) is first converted into a digital signal in the AD converter 2. A
The output of the D converter 2 is supplied to the still image processing circuit 3 and the moving image processing circuit 4, while the motion detection circuit 5 divides the frame difference based on the image edge amount and the image level to obtain the motion signal. Used for detection.

Since the sampling method of the luminance signal is different between the still image area and the moving image area, different decoding processing is required for each area, and the still image processing circuit 3 uses the image data of the previous frame in the still image area. Then, inter-frame interpolation is performed to interpolate the current frame. However, if there is a pan or tilt of the camera, the data position of the previous frame is moved horizontally and vertically, and interpolation is performed according to the position of the current frame, and the front and back lines of the previous field are used for each line. Then, inter-field interpolation for approximately complementing the image data is performed. On the other hand, the moving image processing circuit 4 performs field interpolation for approximately complementing image data using lines before and after the current field in the moving image area, and therefore only the image data of the current field is used. Is used. Further, for the color signal, the same interpolation processing as that for the luminance signal is performed for the still image area and the moving image area. However, since the color signal is line-sequentially multiplexed, the point where the sample point becomes the second line is the luminance. Different from the signal.

The signals of the still picture area and the moving picture area which have been separately processed by the still picture processing circuit 3 and the moving picture processing circuit 4 are supplied to the subsequent mixer 6 and adaptively mixed with a mixing ratio according to the movement of the image. After that, it is supplied to the luminance / color separation circuit 7. The luminance / color separation circuit 7 time-expands the color signals time-compressed line-sequentially and multiplexed in the horizontal blanking period to obtain the luminance signal Y and the color difference signals Pr and Pb. The output of the luminance / color separation circuit 7 is supplied to the DA converter 8, converted into the analog luminance signal Y and the color difference signals Pb and Pr, and then output to the outside.

[0005]

The above-mentioned conventional muse decoder 1 performs separate processing for a still image area and a moving image area, and in the moving image area, field interpolation is used to complement only the image data of the current field. I'm taking the way.
Therefore, with respect to a moving image, unlike inter-field interpolation in which image data is approximately complemented by using lines before and after the previous field for each line, the resolution is reduced to less than half of the original image. However, since the human visual characteristics are much less sensitive to moving objects, the decrease in resolution for moving images is not so noticeable, and the band compression method adopted in the Muse method and the human visual characteristics are consistent. ,
There is no problem in practical use.

However, even though the moving image processing is performed in the range in which the reduction in the resolution of the moving image does not pose a problem in view of human visual characteristics, it is meaningful to provide some compensation to compensate for the reduction in the resolution. Kaihei 2-100
As seen in No. 484 "MUSE Signal Processing Circuit",
The output of the video processing circuit with the video enhancement function and the output of the still image processing circuit are mixed at an appropriate ratio, and further supplied to the still image enhancer whose amount of enhancement can be changed by the motion signal, so that the still image area and the video area A high-definition image processing device has been proposed which is optimized for both. However, since such a conventional high-definition image processing apparatus separately enhances a still image area and a moving image area, two system circuits are required for the enhancement, and the enhancement amount of each of the still image area and the moving image area is required. Since the center frequencies of the enhancements can be set independently of each other, each system has a problem that the circuit configuration is very complicated.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a decoder for decoding a high-vision signal band-compressed according to a predetermined encoding method, and a decoder connected to this decoder for fast movement. An image is provided with an aperture matrix unit for performing high-frequency compensation in a band having a lower spatial frequency.

[0008]

According to the present invention, an aperture matrix unit is connected to a decoder that decodes a high-vision signal that is band-compressed according to a predetermined encoding method, and high-frequency compensation is performed in a band having a lower spatial frequency for a faster moving image. ,
Fast-moving images prioritize contrast over resolution,
For slow-moving images, image creation is performed with priority on resolution over contrast.

[0009]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit configuration diagram showing an embodiment of a high-definition image processing apparatus of the present invention, FIG.
Is a circuit diagram of the aperture matrix unit shown in FIG. 1, FIG. 3 is a diagram showing frequency characteristics of the aperture matrix unit shown in FIG. 2, FIG. 4 is a diagram showing light-dark space-time frequency characteristics, and FIG. FIG. 3 is a diagram showing the relationship between spatial frequency and MTF.

A high-definition image processing apparatus 11 shown in FIG.
In the configuration, the aperture matrix circuit 12 is connected to the DA converter 8 at the final stage of the muse decoder 1 to perform high frequency compensation in a band having a lower spatial frequency for an image having a faster motion. The aperture matrix unit 12 has a luminance signal Y and a color difference signal P.
Three types of emitter peaking circuits 13 and 1 having different high frequency compensation characteristics are provided in the signal paths in r and Pb.
4 and 15 are connected in cascade, and these three types of emitter peaking circuits 13 to 14 are selectively operated in accordance with high-speed, medium-speed, and low-speed motion signals supplied from the motion detection circuit 5. There is. The emitter peaking circuit, for example, 13 shown in the embodiment has a resistor R2 connected in parallel with the emitter resistor R1 of the transistor Q1 whose emitter is grounded.
And a peaking capacitor C1 are connected, and a capacitor C3 is connected in parallel to the collector resistor R3. Therefore, the peaking characteristic defined by the three breakpoint frequencies f1, f2, and f3 is obtained from the emitter peaking circuit 13. However, f1 = 1 / 2π (R1 + R2) C2 f2 = 1 / 2πR2C2 f3 = 1 / 2πR3C3.

Three emitter peaking circuits 13-15
3, the center frequency is slightly shifted from the low frequency side to the high frequency side so that the flat portions of the compensated frequency characteristics do not overlap with each other, as shown in FIG. Therefore, the compensation bands of the emitter peaking circuits 13 to 14 are shifted in the low range, the middle range, and the high range among the high range including many contour components of the image, and only the skirt portion is crossed over. To do. The emitter peaking circuits 13 to 14 are connected to the common-emitter transistor Q.
1, Q11, Q21 are connected to the next stage via buffer transistors Q3, Q13, Q23 for inverting the phases of the emitter outputs, and a peaking capacitor C is also provided.
Transistors Q2 and Q1 that are made conductive by a motion signal from the motion detection circuit 5 between C2, C12 and C22 and the ground.
2, Q22 are connected. That is, if it is a high-speed image showing fast movement, the emitter peaking circuit 13 in the first stage
In the case of a medium-speed image in which the transistor Q2 of FIG.
Transistor Q12 becomes conductive. Then, if the image is a slow moving image, the transistor Q22 of the emitter peaking circuit 15 at the final stage becomes conductive. As long as the respective transistors Q2, Q12, Q22 are not conducted, the emitter peaking circuits 13, 14, 15 are all free from the peaking operation, and therefore, two or more of the three types of emitter peaking circuits 13-15 are provided. However, there is no simultaneous peaking operation.

As described above, the aperture matrix unit 12
In the case of a high-speed image, the emitter peaking circuit 13 in the first stage operates to compensate for a relatively low frequency band in a high frequency range, thereby performing a picture formation in which the contrast is prioritized over the resolution. On the other hand, for a low-speed image, the emitter peaking circuit 15 at the final stage operates to compensate for a relatively high frequency band in a high frequency range, thereby performing picture formation in which resolution is prioritized over contrast. Further, for a medium-speed image, the emitter peaking circuit 14 in the intermediate stage operates to compensate for the intermediate frequency band in the high frequency range, so that it is possible to perform painting with equal emphasis on both contrast and resolution.

In general, various characteristics of sense and perception are psychological and
It can be described by physical means in the same expression method as other image information transmission systems. For example, the appearance of a stimulus in the form of an amplitude modulation of a space sine wave with a time sine wave is called the visual spatiotemporal frequency characteristic, and the isosensitivity locus of the bright and dark spatiotemporal frequency characteristic is the actual measurement example shown in FIG. Has been reported. In the figure, the horizontal axis represents the spatial frequency (cycle per degree).
ee), and the vertical axis represents the time frequency (Hz).
The dB point is the point that gives the optimum viewing condition. Also.
The characteristic of the space-time frequency characteristic on the horizontal axis corresponds to the spatial frequency characteristic based on the appearance of the spatial sine wave pattern, and is also called a response function, MTF (Modul).
FIG. 5 shows the contrast reduction rate of an image having a sine wave distribution on the vertical axis and the spatial frequency on the horizontal axis. The image quality is said to be better as the details are more detailed and the sharpness is higher. The former is determined by the resolution, and the latter is determined by the clarity of the outline portion and the contrast of the image details. Therefore, the sharpness of the image is closely related to the MTF of the image processing system, and the system having the characteristic shown by the solid line in FIG. 5 has a high reproducible limit resolution,
Gives a slightly blurry impression. On the other hand, as shown by the dotted line in FIG. 5, the high-definition image processing apparatus 11 that performs high-frequency compensation according to the movement of the image and changes the contrast reduction rate sacrifices the reproducibility of the resolution surface to some extent. , The contrast reproducibility is enhanced, and reproduction with higher sharpness is possible.

As described above, according to the high-definition image processing apparatus 11, the aperture matrix unit 12 is connected to the muse decoder 1 which decodes the high-vision signal band-compressed according to the predetermined encoding method, and the fast-moving image is obtained. Since it is configured to compensate for high frequencies in a band with a low spatial frequency, we take into account that for fast moving images, nerves are concentrated in the center of movement rather than the details of the image, and human visual sensitivity is reduced. In the above, high-frequency compensation is applied in the low spatial frequency band, and contrast is prioritized over resolution to create pictures.Slow-moving images are more visible to humans than fast-moving images. Considering that even the smallest details are taken into account, the image quality is evaluated subjectively by making a picture that prioritizes resolution over contrast. That performs a picture making, it is possible to sufficiently exhibit the excellent image representation capability provided inherently to the high-definition image.

[0015]

As described above, according to the present invention, an aperture matrix unit is connected to a decoder for decoding a high-vision signal that is band-compressed according to a predetermined encoding method, and a faster moving image has a lower spatial frequency. Since it is configured to compensate for high frequencies in the band, for a fast-moving image, it is necessary to take into consideration that the nerve is concentrated in the center of the motion rather than the details of the image, and the human visual sensitivity is reduced. High-frequency compensation is applied in the low frequency band, and the contrast is prioritized over resolution to create a picture.Slow-moving images are more visible to humans than fast-moving images, and even the smallest details in the image are noticeable. In consideration of the quality of the image, by making the image with priority on the resolution rather than the contrast, the image with high image quality is evaluated by subjective evaluation, and the high-definition image is created. Inherent to the provided superior image representation capability an excellent effect such as can be sufficiently exhibited.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of a high-definition image processing apparatus of the present invention.

FIG. 2 is a circuit diagram of the aperture matrix unit shown in FIG.

3 is a diagram showing frequency characteristics of the aperture matrix unit shown in FIG.

FIG. 4 is a diagram showing light-dark space-time frequency characteristics.

FIG. 5 is a diagram showing a relationship between spatial frequency and MTF.

FIG. 6 is a circuit configuration diagram showing an example of a conventional muse decoder.

[Explanation of symbols]

 1 Muse Decoder 5 Motion Detection Circuit 11 Hi-Vision Image Processing Device 12 Aperture Matrix Unit 13, 14, 15 Emitter Peaking Circuit

Claims (1)

[Claims] 1. A decoder for decoding a high-vision signal band-compressed according to a predetermined encoding method, and an aperture matrix unit connected to this decoder for high-frequency compensation in a band having a lower spatial frequency for a moving image. A high-vision image processing device characterized by: