JPS63121362A - Signal processor - Google Patents

Abstract

PURPOSE:To execute signal processing with emphasis on a minute change in a subject and without emphasis on an outline part by adding an aperture correction signal which is gainadjusted by means of an output control signal from a signal level judgment device to an output signal from a gamma correction device. CONSTITUTION:An input signal 106 is supplied to the gamma correction device 101, and a gamma correction signal 107 is supplied to an aperture correction device 102 and it is given to the signal level judgement device 103. Said device 103 holds a signal level for previous and subsequent several clocks of the current signal level and detects the signal level more than a prescribed threshold among these signal levels. A gain control device 104 is controlled in such a way that the gain of an aperture correction signal 108 becomes small while the signal level more than the prescribed valve is detected. An adder 105 adds and outputs the signal 107 and a gain-controlled aperture correction signal 110. A signal processing with emphasis on the minute change in a subject and without emphasis on an outline part can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a signal processing device having an aperture correction device used in a video camera or the like.

2. Prior Art As a conventional signal processing device, for example,
This is shown in Japanese Patent No. 7878.

Figure $6 shows a block diagram of this conventional signal processing device. 601 is a gamma correction device, 602 is an aperture correction device, and 603 is an addition device.

In the conventional signal processing device configured as described above, a gamma-corrected signal and an aperture correction signal created from this signal are added. Adding device 76
The output signal 03 is an aperture-corrected video signal.

If the signal for aperture correction is increased in order to emphasize the minute change component, which is the problem that the invention aims to solve, the contour parts of the subject where there are large changes will be unnaturally overemphasized, and the image quality will deteriorate. There was a problem with this.

In view of this, it is an object of the present invention to provide a signal processing device that emphasizes minute changes in a subject and does not emphasize contours of the subject so much.

Means for Solving the Problems The present invention provides a gamma correction device that performs gamma correction on a desired signal, an aperture correction device that creates a signal for aperture correction, and a signal level judgment device that judges the magnitude of a signal level. , a gain control device that controls the output signal level from the aperture correction device using an output control signal from a signal level determination device, and a gain-adjusted aperture correction signal that is an output signal from the gain control device and a gamma correction device. This is a signal processing device equipped with an adding device that adds output signals of

Operation According to the present invention, the signal level for aperture correction can be completely controlled by the above-described configuration, and an appropriate aperture signal corresponding to each subject can be obtained.

Embodiment FIG. 1 is a block diagram of a signal processing device in a first embodiment of the present invention. In FIG. 1, 101 is a gamma correction device, 1o2 is an aperture correction device, 103 is a signal level judgment device, 104 is a gain control device, 1o
6 is an adding device.

The operation of the signal processing device of this embodiment configured as described above will be described below.

When the input signal 106 to the gamma correction device 1o1 has a step response waveform as shown in FIG.
07 is as shown in the figure. Aperture correction device 10
The aperture correction signal 108 obtained from 2 is as shown in FIG. In FIG. 2, the vertical axis direction indicates the signal level.

Here, the signal level determination device 103 holds signal levels for several clocks before and after the current signal level, and detects those signal levels that are above a certain threshold value among these signal levels. Then, while a signal level equal to or higher than a certain threshold is being detected, the output signal 109 from the signal level determination device 103 is input to the gain control device 104 so that the gain of the aperture correction signal 108 becomes small.

FIG. 2d shows the gain control signal 109i from the signal level determination device 103. At this time, a threshold value AT is set in the signal level determination device 103.

The input/output relationship of the signal level determination device 103 is shown in FIG. 3a. Further, as shown in FIG. 2, the period during which the input signal to the signal level determination device 103 is held is 2TH. Therefore, input signal 1 to signal level determination device 103
The gain control signal 109 becomes smaller from a time TH before the signal level of signal 07 exceeds the threshold value AT.

Then, the signal level of the input signal 107 is the threshold value AT=
The gain control signal 109 returns to its original state at a time TH delayed from the time when it falls below 2.

That is, the gain of the aperture correction signal is kept small as shown in FIG. 2e until the aperture correction signal is generated and terminated.

Therefore, the output signal 111 from the adder 105 is the second
As shown in FIG. f, a video signal having an appropriate aperture correction signal can be obtained.

Note that the number of thresholds set in the signal level judgment device 103 is not limited to one, and the aperture correction signal can be determined even if a plurality of thresholds or a continuously changing threshold is used. can be controlled.

Figures 3 and 3c show a case where there are a plurality of threshold values and a case where the threshold value changes continuously in the input/output relationship of the signal level determination device 103, respectively.

Furthermore, how much of the input signal is held in lock state in the signal level determination device 103 depends on the sampling clock frequency and aperture correction characteristics of the signal.

FIG. 4 is a block diagram of a signal processing device showing a second embodiment of the present invention. The difference from the configuration in FIG. 1 is that the input signal to the aperture correction device 102 is a signal 106 before being gamma corrected.

Therefore, the input signal to the aperture correction device 102 is
In the case of a step response waveform as in the case shown in the figure, the output signal 108 from the aperture correction device 102 becomes as shown in FIG. 6a. In this case, since the signal for aperture correction is created using a signal that has not been gamma corrected, the signal waveform has symmetry, has more high frequency components than in Figure 2C, and has natural contour components. It becomes.

Thereafter, the same processing as in the case of FIG. 2 is performed to generate the aperture correction signal as shown in FIG. 5, and the output signal 111 from the adder 105 becomes as shown in FIG. 6C.

Note that the input signal to the signal level determination device 103 may be an output signal from the gamma correction device 101 or an input signal to the gamma correction device 1.02.

As described in detail, according to the present invention, it is possible to perform signal processing that emphasizes only minute change components of the subject and does not emphasize contour parts where there are large changes in the subject, resulting in very natural images. obtained, and its practical effects are great.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a signal processing device according to an embodiment of the present invention, FIG. 2 is an operation waveform diagram of the same embodiment, FIG. 3 is a characteristic diagram showing the input/output relationship of the signal level determination device, and FIG. 4 6 is a block diagram of a signal processing device according to another embodiment of the present invention, FIG. 6 is an operation waveform diagram of the embodiment shown in FIG. 4, and FIG. 6 is a block diagram of a conventional signal processing device. 1o1... Gamma correction device, 1o2...,...
-Aperture correction device, 103...signal level judgment device, 104...gain control device, 1o5...addition device. M2 Figure 3 Figure 5

Claims (3)

[Claims] (1) A gamma correction device that performs gamma correction on an input signal, an aperture correction device that creates a signal for aperture correction, a signal level judgment device that judges the magnitude of a signal level, and an output from the aperture correction device. a gain control device that controls a signal level by an output control signal from the signal level determination device; a gain-adjusted aperture correction signal that is an output signal from the gain control device; and an output signal from the gamma correction device. A signal processing device comprising: an addition device that performs addition. (2) The signal processing device according to claim 1, wherein the input signal to the aperture correction device is an output signal from a gamma correction device. (3) The signal processing device according to claim 1, wherein the input signal to the aperture correction device is the input signal.