JPS62285582A - digital image processing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] 1. Detailed Description of the Invention [Field of Industrial Application] The present invention improves the image quality by performing digital image processing on a television signal taken by a camera using a high-sensitivity photographic tube to photograph a very dark subject. The present invention relates to an improved digital image processing device.

[Conventional technology]

In order to take pictures of extremely dark subjects, the imaging section uses a high-sensitivity imaging tube, S iT (Silicon Intensif).
I (Imare Intensi) camera using IerTarget) W or CCD camera 2
A camera with f ies , ) is used. S
Cameras that have been made highly sensitive using IT or II will have a grainy screen due to the extra noise generated by SIT or II.

For example, when photographing the night sky, the part of the night sky that is supposed to be uniformly dark does not become uniformly dark due to extra signals such as l)l# current generated by SIT and II. Therefore, in order to improve the image quality of the video signal from such a camera using a digital image processing device, the video signal from the camera is integrated for a specified number of frames, random noise is reduced, and then the light incident on the camera is cut. By extracting only the fixed pattern noise and subtracting the same number of frames from the previously integrated signal, image quality is improved by eliminating components due to uneven characteristics of the imaging unit and interference from the electronic circuit.

[Problems to be solved by the present invention]

In the conventional image processing method described above, integration is started and the screen level gradually increases, but in normal control,
To determine how far to integrate, there are several methods, such as constantly monitoring the process of integration and stopping when it reaches an appropriate level, or (B) specifying the integration time and integrating for a certain period of time. It becomes necessary.

However, in any of the above methods, it is inconvenient because it is not possible to determine whether the level of the integrated result is good unless it is integrated.

1 [Means for solving the problem] The present invention includes an A/D conversion circuit that converts a video signal from a television camera into a digital signal, a sensitivity switching circuit that controls coefficients of λ/D converted data, It has an addition/subtraction circuit that adds and subtracts two input signals, a 1-frame memory circuit that delays or stores the output signal of the addition/subtraction circuit by 1 frame, and a D/A conversion circuit that converts the 1-frame memory circuit output signal to J)/A. The two input signals of the addition/subtraction circuit are configured such that the output of the sensitivity switching circuit and the output of the one frame memory circuit are input. By controlling the coefficients of the sensitivity switching circuit depending on whether to improve the image quality of the video signal or to check the level after integration, the image processing operation can be made easier by allowing quick confirmation. I have to.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a system diagram of an embodiment of the present invention. A video signal from a television camera is input to an input signal terminal 1 and converted into a digital signal by an A/D conversion circuit 2. A/L) The coefficients of the converted data are controlled by the sensitivity switching circuit 3. The addition/subtraction circuit 4 adds or subtracts the output signal of the sensitivity switching circuit 3 and the output signal of the 1-frame memory circuit 5 to obtain 1
)/A conversion circuit 6 performs D/A conversion and outputs it to an output signal terminal 7.

In order to improve the image quality, the addition/subtraction circuit 4 adds a fixed number of frames, and the integrated one frame signal is stored in the one frame memory circuit 5. This reduces random noise in the camera video signal.

The coefficients of the sensitivity switching circuit can be easily set by bit shifting, and as the number of images to which small coefficients are added increases, the improvement rate of random noise increases.

Next, the light incident is cut off, only the fixed pattern noise is output, and the adder/subtractor circuit 4 subtracts the number of phenoms for one foot, and the one frame signal obtained by subtracting the same number of frames from the previously integrated signal is stored. This removes components due to uneven characteristics of the photographing section and interference from the electronic circuit, improving image quality.

At this time, assuming that a video signal with a level G times higher than the input is obtained in the frame memory, the coefficient of the sensitivity switching circuit 2 is set to 1.
/256 times, the NT8C adds 30 sheets per second, so the required integration time T is as follows.

It takes too much time to judge how much integration should be done after the integration time T (seconds) has elapsed. If G, the integration time T becomes, and the determination can be made in a short time.

〔Effect of the invention〕

As explained above, the present invention converts a video signal from a television camera into an A/D K converter and adds and subtracts a certain frame video signal to improve the image quality of the video signal, and when checking the level. Controlling the sensitivity switching circuit has the effect of shortening the p-plane area processing time and facilitating operation.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an embodiment of the present invention. 1...Input signal terminal, 2...A/D conversion circuit,'3...Sensitivity switching circuit, 4...-
・Addition/subtraction circuit, 5...1 frame memory circuit,
6...D/A conversion circuit, 7...Output signal terminal.

Claims (1)

[Claims] In a device that improves the image quality of a television camera signal for photographing a dark place, an A/D conversion circuit converts the video signal from the television camera into a digital signal, and a sensitivity switching circuit controls the gain of the A/D converted data. It has an adder/subtracter circuit that adds and subtracts two input signals, a 1-frame memory circuit that delays or stores the adder/subtracter output signal by 1 frame, and a D/A conversion circuit that converts the 1-frame memory circuit output signal from D/A. The addition/subtraction circuit is configured such that the output of the sensitivity switching circuit and the output of the 1-frame memory circuit are input, and the sensitivity switching circuit is configured to input the output of the sensitivity switching circuit and the output of the one frame memory circuit, and switch the sensitivity depending on whether to improve the image quality of the video signal or to check the level. A digital image processing device characterized by facilitating image processing operations by controlling a circuit's gale.