JPH0410881A - Television image receiver - Google Patents

Abstract

PURPOSE:To reduce visual out-of-focus easy to be recognized at a place conditional change of which is hard by controlling luminous level change when a video signal changes from a still condition to a moving condition or in the opposite case of it so as to be comparatively gradual. CONSTITUTION:A temporal interpolating circuit 1 of a still picture processing system and an interpolating within field circuit 2 of a moving picture processing system are provided to an input video signal and respective outputs are mixed moderately by a movement detecting signal with a mixer 3. The output of the mixer 3 is added with a correcting signal in an adder 10 and an output video signal is obtained. Then, the output of the temporal interpolating circuit 1 of the still picture processing circuit is supplied to a frequency difference extracting circuit 4, the part of a difference with the reproducing frequency band of the moving picture processing system is extracted and the output of the frequency difference extracting circuit 4 is attenuated by a multiplier 7. Thus, it becomes hard to feel as out-of focus by reducing the level change when it moves from a still condition to a moving condition.

Description

[Detailed description of the invention] "Industrial application field" This invention is a so-called high-definition television system.

"Prior Art" In a television receiver used as a receiving terminal for a broadcasting system called a high-definition television system,
For still images, temporal interpolation is performed to improve the spatial resolution, and for moving images, intra-field interpolation is applied and signal processing is performed separately, and these are mixed appropriately using the motion detection signal. An output image signal (output video signal) is obtained.

"Problems to be Solved by the Invention" According to this signal processing, the spatial resolution of still images is improved, but this creates a difference in resolution between them and moving images.

In other words, the frequency bands to be reproduced will be different.

In general, it is said that humans' visual characteristics for moving images are low, but images with high frequency components, such as fine ↓) tI
When something suddenly starts moving from a stationary state, it feels visually blurry.

When an object with high-frequency components changes from a stationary state to a moving state, the image feels blurry 1
One reason is the perception of a decrease in brightness due to changes in the image amplitude.

As shown in Figure 5, a signal that is outside the reproduction band of a moving image has an amplitude in a stationary state, as shown in Figure A, but as soon as it enters a moving state, the amplitude disappears, as shown in Figure B. is the average level (DC value) of the amplitude in a stationary state.

This kind of change in state makes you feel blurry.

Also, if you consider the above in terms of high amplitude parts, you will notice that something that shines brightly when it is stationary loses its shine as soon as it starts moving.

Humans have high visual sensitivity to changes in brightness level, so they perceive the image to be blurry in response to this state change phenomenon. Therefore, when signal processing such as aperture correction is performed to lift the high range of the signal band for contour correction, the difference in amplitude changes becomes larger, and in this case, blurring occurs. The phenomenon becomes more and more noticeable.

The present invention solves the above problems and proposes a television receiver that performs image processing that reduces the appearance of blur.

"Means for Solving the Problems" In order to solve the above problems, the present invention provides a still image signal processing system, a video signal processing system, and a mixer that mixes the outputs of these systems to obtain a predetermined video signal. and a frequency difference extraction circuit that extracts a frequency band portion different from the video signal provided in the still image signal processing system, and a frame difference creation circuit that creates a motion detection frame difference based on motion detection No. 48, The present invention is characterized in that the amount of addition output of the frequency difference to the video signal is controlled based on this frame difference.

``Function'' Focusing on the fact that the human eye recognizes a blurry image when it reacts to a sudden change in the brightness level, this invention provides a method for changing the image from a stationary state to a moving state (or vice versa). Efforts have been made to reduce level changes when moving.

Therefore, the correction signal which is the frequency difference (1) of still image processing outputted from the frequency difference extraction circuit 4 is mixed with the output video signal. The mixing amount can be controlled to tml based on the frame difference signal (switch control signal for the changeover switch 9 in FIG. 1) created from the motion detection signal.

Alternatively, as shown in FIG. 4, the correction signal is closely controlled by the level of the switching control signal.

"Example" Next, an example of a television receiver according to the present invention will be described in detail with reference to the drawings.

This invention focuses on the fact that the human eye recognizes blurry images when it reacts to sudden changes in the brightness level, and controls the level to avoid extreme changes when moving from a stationary state to a moving state. be done.

That is, if the object was in a stationary state one frame before and entered a moving state in the current frame, the luminance level changes from frame to frame as shown in FIG. The greater this level change, the more likely it is to feel blurred.

As shown in FIG. 3, a correction value (the level indicated by the broken line) is added to the current frame to make the level change smaller or to make the change slower. This will make the blur less noticeable. As the correction value, a signal using high-frequency components of a still image system is used.

Further, since still image systems normally perform temporal interpolation, a moving image portion becomes a double image, so this correction value cannot be added all the time.

Therefore, a motion detection signal is used to detect a change from a stationary state to a moving state, and only when there is a large change, a correction value component is added in this case.

Next, contrary to the above, there is a change from a moving state to a stationary state, and in this case, the correction value is subtracted in reverse. In this case, since the polarity is different from that in the case of a change from a stationary state to a moving state, the correction value is inverted and added to the output video signal.

The configuration shown in FIG. 1 is a concrete example based on the above correction concept.

In the high-definition television receiver shown in the figure, a temporal interpolation circuit 1 of a still image processing system is applied to an input video signal.
and a video processing system field interpolation circuit 2,
The respective outputs are appropriately mixed at mixing N3 using the motion detection signal. The output of the mixing M3 is added to the above-mentioned correction No. 48 in the addition MIO to obtain an output video signal.

In this invention, the output (still image No. 48) of the temporal interpolation circuit 1 of the still image processing system is the frequency difference extraction circuit v84.
The difference between the frequency band and the reproduction frequency band of the moving image processing system can be extracted.

Therefore, this frequency difference extraction circuit 4 has a two-dimensional or one-dimensional low-pass filter 5 whose passband is a band corresponding to the reproduction frequency band of the moving image processing system, and a still image signal is supplied to this filter. Its output and temporal interpolation circuit 1
The output of is supplied to the subtracter 6 to complete the subtraction process.

The output of the frequency difference extraction circuit 4 is attenuated by a multiplier 7. Here, the multiplier 7 is used as an attenuator because
This is to make the level lower than the original level. Therefore, multiplier 7
It is also possible to use a low-pass filter instead of .

This multiplication output can be used as a correction signal and is supplied to the exclusive OR circuit 8. The other side of the exclusive OR circuit 8 is supplied with a sign bit of a frame difference detection signal, which will be described later.

Since the sign bit is different when the state of the video signal changes from a static state to a moving state and vice versa, the correction signal that can be output from the exclusive OR circuit 8 depends on the positive or negative content of this sign bit. The polarity of can be changed.

That is, when the image changes from a still image state to a moving image state, the polarity of the correction signal becomes "negative", and when the image changes from a moving image state to a still image state, the polarity becomes "positive".

The correction signal is supplied to the addition MIO via the changeover switch 9. The other side of the changeover switch 9 is fully input with the "0" level. Here, the "0" level is 0 for positive and negative values.

The switching control signal for the changeover switch 9 uses No. 48, which is one frame difference of the motion detection signal, and is formed as follows.

A motion detection signal is supplied to the mixer 3 from a terminal 3a.

This motion detection signal is also supplied to a frame difference detection circuit 11 to detect a frame difference. Therefore, this frame difference detection circuit 11 is composed of a frame memory lla and a subtracter 11b, and calculates the frame difference by subtracting the motion detection signal delayed by one frame in the frame memory 11a and the motion detection signal of the current frame. is detected.

Of this frame difference detection signal, the sign bit is fully supplied to the above-mentioned exclusive OR circuit 8, and the frame difference detection signal itself is converted into an absolute value by an absolute value conversion circuit 13. Thereafter, it is input to the comparator 14.

When the image changes from a still image state to a moving image state, or vice versa, the 21 frame difference value of motion detection No. 48 increases. Therefore, this reference level is set so that it applies when the state of video No. 48 changes significantly.

As a result, only when there is a major change in the state of Video No. 48,
High level switching control! An Il signal is obtained, which switches the changeover switch 9 to the state shown.

As a result, the output video signal is corrected by the level of the correction signal (
(addition or subtraction), thereby making it possible to correct sudden level changes in output video No. 48.

When the state change of the video signal is small, a "0" level signal is added to the output video signal as a correction signal, so in this case, the output video signal becomes the same and there is no level change.

As described above, the polarity of the correction signal 48 consisting of the frequency difference is controlled by the sign bit of the frame difference detection signal, and whether or not to add the correction signal is controlled by the switching control signal.

Therefore, the correction signal added to the output image 48 can be controlled depending on whether the state change of the video signal is in the direction of increasing or decreasing the level, and depending on the magnitude of the state change with respect to the reference value.

Therefore, an appropriate state change can be achieved.

FIG. 4 shows another specific example of the invention.

In this example, the value of the correction signal itself can also be controlled.

Therefore, the changeover switch 9 becomes unnecessary. At the same time, the comparator 14 becomes unnecessary.

Instead, the multiplication coefficient of the multiplier 7 is configured to be externally variable, and the absolute value output of the frame difference detection signal is supplied to the multiplier 7 as its multiplication coefficient control signal.

In this way, the value of the correction signal itself, which is the multiplication output, is controlled based on the frame difference detection signal, and its polarity is controlled by the sign pit of the frame difference detection signal, so more appropriate state changes can be achieved. can.

It is also possible to use an integer number of the above-mentioned frame memories lla, and it goes without saying that when such an integer number is used, changes in the state of the video signal can be detected more accurately.

"Effects of the Invention" As described above, according to the present invention, the luminance level changes relatively slowly when a video signal changes from a static state to a moving state, and vice versa. .

According to this, visual blur that is easily recognized in areas where conditions change rapidly is reduced, and more natural images can be reproduced.

[Brief explanation of drawings]

1 and 4 are system diagrams of essential parts showing an example of a television receiver according to the present invention, FIGS. 2 and 3 are explanatory diagrams showing changes in brightness level, and FIG. 5 is a moving image FIG. 3 is a diagram showing a reproduction signal obtained by still image processing and moving image processing of a reproduction out-of-band video signal. 2 ・ ・ 3 ・ ・ 5 ・ ・ 7 ・ ・ 8 ・ − 9 ・ ・ 11 Salary ・ 11a ・ ・ 11b ・ 13 ・ ・ 14 Temporal interpolation circuit, intra-field interpolation circuit, mixer, frequency difference extraction circuit, 2-dimensional or 1-dimensional low-pass filter, subtracter, multiplier, exclusive OR circuit, changeover switch, addition factor, frame difference detection circuit, frame memory, reduction jlEN, absolute value circuit, comparator signal - 凰 signal "Nine signal I1 to signal I1 roaring signal I signal I1 ^ Figure 3 Stationary area Moving area Figure 5

Claims (1)

[Claims] (1) A still image signal processing system, a video signal processing system, a mixer that mixes the outputs of these to obtain a predetermined video signal, and a mixer that mixes the outputs of these systems to obtain a predetermined video signal, and a frequency band portion different from the video signal provided in the still image signal processing system. It has a frequency difference extraction circuit for extracting a frequency difference, and a frame difference creation circuit for creating a motion detection frame difference based on a motion detection signal, and controls the addition output amount of the frequency difference to the video signal based on this frame difference. A television receiver characterized by: