JPH07203286A - Line sensor camera - Google Patents

Abstract

PURPOSE:To realize flicker cancellation with high accuracy by extracting a flicker component from a video signal obtained through image pickup of an actual object in the camera using a line sensor so as to obtain the flicker component very close to filcker of an object. CONSTITUTION:Part of a scanning period of a video signal (A) obtained by picking up an image of an actual object is used for a flicker component extracted part and its signal level is acquired as a lighting quantity for that point of time, and a sample-and-hold circuit 3 uses a sampling pulse (b) to sample and hold the signal part. The resulting signal (C) is inverted by a correction waveform generating circuit 4 and the resulting signal (D) is fed to an amplifier circuit 4, in which reverse correction is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera using a one-dimensional linear sensor.

[0002]

2. Description of the Related Art A linear sensor camera generally uses a scanning speed of several hundredths of a second to a thousandths of a second, but when used under the illumination of a fluorescent lamp or a mercury lamp, which has a lot of flicker components. Is 100Hz synchronized with the power supply frequency
Or, the fluctuation of the image level due to the flicker of 120 Hz becomes a problem. In order to reduce this flicker, conventionally, the method shown in the block diagrams of FIGS. 3 and 4 has been used.
In this case, in each case, in the amplifier 4, the input terminal 1
The flicker included in the video signal input to is corrected so as to be canceled by the separately extracted flicker component as described below. In the example shown in FIG. 3, the full-wave rectifier circuit 8 extracts the frequency component of the power source from the commercial power source 7 and the flicker component from the signal. Further, in the example of FIG. 4, the flicker component extraction circuit 10 is provided by separately providing the light receiving element 9.
The flicker component is extracted more.

[0003]

In the conventional flicker component extraction method, unlike the flicker component of illumination at the position of the object captured by the line sensor, it is unsuitable for correction. In other words, if there are multiple lights that illuminate the subject, or if mercury and halogen lights are used together, the flicker component will not be sinusoidal and will differ from the sinusoidal power waveform from the commercial power supply. Not suitable for correction. In addition, it is often very difficult to provide a light-receiving element when the subject position is at a long distance, and when it is installed at a place far from the subject position, due to the difference in illumination conditions, the line sensor and the light-receiving element are also different. Since the sensitivity characteristics are different, it is difficult to extract the flicker component suitable for correction, and both methods are not practical. It is an object of the present invention to provide a line sensor camera capable of performing flicker cancellation with high accuracy by extracting a flicker component from an actual illumination state of a subject and obtaining a video correction signal, excluding the above-mentioned drawbacks.

[0004]

In order to achieve the above object, the present invention utilizes a part of a video signal obtained from a linear sensor itself which is actually capturing an image of an object as a flicker component extraction signal, and cancels flicker. It is a signal.

[0005]

The operation of the present invention will be described. A part of a video signal obtained from a linear sensor for picking up an object is used as a flicker component extraction unit, the signal level thereof is taken as an illumination amount at that time, and it is sampled and amplified. Flicker is canceled by applying reverse correction in the circuit.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram and FIG. 2 is a signal waveform diagram. Note that the symbols of the signals in FIG. 1 and the symbols of the signal waveforms in FIG. 2 correspond. In FIG. 1, the video signal (A) obtained from the line sensor is input to the input terminal 1 and the input terminal 2
A sampling pulse (B) is input to. The sample hold circuit 3 holds the level of the flicker component extraction period 5 by the sampling pulse (B) synchronized with the flicker component extraction period 5 to obtain a sample hold signal (C). The sample hold signal (C) is inverted and amplified by the correction waveform generating circuit 4 to obtain the flicker correction signal (D). Based on the obtained correction signal (D), the video signal (A) is generated by the amplifier circuit 5.
Reverse correction is applied to. By repeating this for each scan cycle of the line sensor, it is possible to correct the flicker of the video signal.

The operation will be described with reference to the signal waveform diagram shown in FIG. The waveform (A) is a video signal waveform containing a flicker component, and the video level of the flicker component extraction period 6 of this video is sampled and held by the sampling pulse of the waveform (B). A waveform obtained by repeating this is shown in (C). Waveform (D)
Is a correction signal obtained by inverting the waveform (C) and supplies this signal to the amplifier circuit 5 to change the video signal gain to correct the flicker component of the waveform (A). Waveform the corrected video signal waveform
Shown in (E).

[0008]

According to the present invention, since the flicker component is extracted from the video signal obtained by picking up the actual subject,
A flicker component that is very close to the flicker of the subject is obtained,
A highly accurate flicker cancellation can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a signal waveform diagram according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional method.

FIG. 4 is a block diagram showing a conventional method.

[Explanation of symbols]

 1 Video signal input terminal 2 Sampling pulse input terminal 3 Sampling hold circuit 4 Corrected waveform generation circuit 5 Amplification circuit 6 Flicker component extraction period 7 Commercial power supply 8 Full-wave rectifier circuit 9 Light receiving element 10 Flicker component extraction circuit A Includes flicker component Video waveform B Sampling pulse waveform C Sample and hold waveform DC Inverted waveform of E E Video waveform after flicker correction

Claims (1)

[Claims] In a camera using a one-dimensional linear sensor, a flicker component due to illumination of an object is detected by sampling and holding a part of a period of the image signal from an image signal obtained by the camera capturing an image of the object. A line sensor camera characterized by extracting and correcting a video signal so as to remove a flicker component.