JPS6217428B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a contour compensating device that can uniformly reduce the "blurring" of the contour of an image over the entire screen and obtain a screen of good quality.

Photoconductive image pickup tubes, which have recently been widely used as image pickup tubes for color cameras, have a characteristic that the beam aperture response falls gently from a relatively low frequency, resulting in an edge enhancement effect similar to image orthicon. It is well known that contour compensation is necessary because there is no image sharpness, that is, the image sharpness is insufficient.

A conventional method for obtaining a contour-compensated video signal will be explained using FIGS. 1 and 2. In the block configuration diagram of FIG. 1, 1 is a vertical contour compensation circuit section, 2 is a horizontal contour compensation circuit section, 3 is an input terminal, 4 and 5 are delay lines for one horizontal scanning period (1H), 6 is an adder circuit, 7 is a subtraction circuit, 8 and 9 are delay lines, 10 is an addition circuit, 1
1 is a subtraction circuit, 12 is a subtraction circuit, and 13 is an output terminal.

When a signal a as shown in FIG. 2a arrives at the input terminal 3, it passes through 1H delay lines 4 and 5, and signals b and c having waveforms shown in FIG. 2b and c are obtained. Adding the signals a and c by 1/2 in the adding circuit 6 produces a signal d as shown in Figure 2 d, and subtracting this signal d from the signal b in the subtracting circuit 7 produces a vertical signal as shown in Figure 2 e. An edge emphasis signal e is obtained, and when the signals b and e are added together in an adder circuit 12, a signal f in which the vertical contour is emphasized is obtained as shown in FIG. 2f. For horizontal contour compensation, the delay time of the delay lines 8 and 9 is selected to be half the time τ corresponding to the frequency at which contour enhancement is desired, and a contour compensation signal is obtained using the same circuit configuration as in the vertical case described above.

However, in general, on the imaging side, the periphery of the screen is more blurred than the center of the screen due to ``focus blur'' around the periphery of the camera lens and ``blur'' around the periphery of the image pickup tube. The beam is thicker at the periphery than at the center, and the amount of "blur" at the periphery is also large. Therefore, if uniform contour compensation is performed on the screen as described above, even if the amount of compensation is appropriate at the center, it will be insufficient at the periphery, and conversely, if the optimal adjustment is made at the periphery, it will be over-compensated at the center. This has the disadvantage that the image becomes unnatural with excessively emphasized contours.

The present invention aims to eliminate the above-mentioned drawbacks by changing the amount of contour compensation between the center and the periphery of the screen, and to provide a contour compensation device that can obtain commercial quality images. An embodiment of the present invention will be described below with reference to FIGS. 3 and 4. Third
The figure is a block configuration diagram of this embodiment, in which 30 is a video signal input terminal, 31 and 32 are 1H delay lines, 33 is an addition circuit, 34 is a subtraction circuit, 35 is an addition circuit, 36,
37 is a modulation circuit, 38, 39, 48 are delay lines, 4
0 is an addition circuit, 41 is a subtraction circuit, 42 is a horizontal synchronization signal HD input terminal, 43 is a vertical synchronization signal VD input terminal,
44 and 45 are parabolic waveform generation circuits, 46 is an adder circuit, and 47 is an output terminal.

The video signal applied to the input terminal 30 is transmitted through two
The adder circuit 33 adds 1/2 to the video signal delayed by 2H through the 1H delay lines 31 and 32, and this output signal is added to the video signal delayed by 1H through the 1H delay line 31 in the subtraction circuit 34. Upon subtraction, a vertical contour compensated signal is obtained. Next, when the frequency at which contour enhancement is desired is assumed, two delay lines 38 and 39 having a delay time of 1/2=τ, an adder circuit 40, and an adder circuit 41 are used to perform the same as the vertical contour compensation signal described above. A horizontal contour compensation signal is obtained by a subtraction circuit 41. After the vertical contour compensation signal is synchronized with the horizontal contour compensation signal by a delay line 48 having a delay time τ, the vertical and horizontal contour compensation signals are added together by an adder circuit 35 to obtain the contour compensation signal of FIG. 4g. obtain. On the other hand, from the horizontal synchronization signal HD and vertical synchronization signal VD applied to the horizontal synchronization signal (HD) input terminal 42 and the vertical synchronization signal (VD) input terminal 43, parabola generation circuits 44 and 45 generate horizontal and vertical periods, respectively. The contour compensation signal g is first modulated by the modulation circuit 36 using the parabolic waveform h having a horizontal period (FIG. 4h, i) to obtain the waveform shown in FIG. 4j. This output signal j is modulated by a parabola waveform i with a vertical period in a modulation circuit 37, and is modulated with the parabola waveform i with a horizontal and vertical period, and a contour compensation signal (Fig. 4 k ). Further, the video signal delayed by (1H+τ) output from the τ delay line 38 and the contour compensation signal k are added together in an adder circuit 46 to obtain a contour-compensated video signal at an output terminal 47.

In setting the compensation amount, first, the compensation amount is set so that the contour compensation is optimal at the center of the screen. Next is contour compensation for the periphery. For the periphery in the horizontal direction, the amount of compensation for the center and periphery can be changed by adjusting the amplitude of the horizontally periodic parabolic waveform h, which is a modulated wave. In addition, regarding the peripheral portion in the vertical direction, the amount of compensation for the center portion and the peripheral portion can be changed by adjusting the amplitude of the vertical period parabolic wave combination i, which is a modulated wave.

In the above embodiment, the contour compensation signal k in FIG.
As shown in the figure, since the amount of compensation at the periphery of the display screen is larger than the amount of compensation at the center, it is possible to compensate for the apparent "blur" that is especially large at the periphery, and it is It is possible to uniformly suppress "blur" and produce a good image.

As described above, the present invention has the advantage of uniformly suppressing "blur" over the entire screen and obtaining a high-quality screen by setting the optimal amount of contour compensation for the center and peripheral areas of the screen. The present invention provides a contour compensating device.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing an example of a conventional contour compensation device, FIG. 2 is a main part waveform diagram for explaining FIG. 1, and FIG. 3 is a block configuration diagram showing an embodiment of the present invention. FIG. 4 is a main part waveform diagram for explaining FIG. 3. 31, 32...1H delay line, 33...Addition circuit, 34...Subtraction circuit, 35...Addition circuit, 3
6, 37... Modulation circuit, 38, 39, 48... Delay line, 40... Addition circuit, 41... Subtraction circuit, 4
2...Horizontal synchronization signal input terminal, 43...Vertical synchronization signal input terminal, 44, 45...Parabola waveform generation circuit, 46...Addition circuit.

Claims (1)

[Claims] 1 two 1-horizontal scanning period delay lines, an adder circuit,
means for obtaining a vertical contour compensation signal from a subtraction circuit; two delay lines with a delay time τ; an addition circuit; means for obtaining a horizontal contour compensation signal from a subtraction circuit; and the vertical contour compensation signal and the horizontal contour compensation signal. two parabolic waveform generation circuits that obtain parabolic waveforms with horizontal and vertical periods; and a first modulation circuit that modulates the contour compensation signal with parabolic waveforms with horizontal periods. , said first
a second modulation circuit that modulates the output signal of the modulation circuit with a vertically periodic parabolic waveform; and a contour compensation signal modulated with the horizontal and vertical parabolic waveforms output from the second modulation circuit through the one horizontal scanning period delay line. and an addition circuit that adds the video signal that has passed through the delay line with the delay time τ.