JPH0698261A - Infrared image pickup device equipped with image correction circuit - Google Patents

Abstract

PURPOSE:To reduce the occurrence of image nonuniformity, etc., and to obtain a video with high quality by correcting the dispersion of an image at every detecting element by prescribed correction data when a gain is changed. CONSTITUTION:The correction coefficients of both the gain and offset of each detecting element are calculated at an image correction data calculation circuit 8 based on gain information and offset information at every detecting element, however, when the gain is varied, the correction coefficient is read out from correction coefficient memory 7 based on a signal from a control circuit 4, and a new correction coefficient is calculated by multiplying by gain change quantity, and it is stored in the memory 7 again. When a time required for the stabilization of the gain elapses, sequence is returned again to its original sequence, and the control circuit 4 controls an image dispersion detection circuit 3 and the circuit 8 so as to perform the regular operation of the circuit 3. Thereby, it is possible to eliminate a noise in gain switching when image correction is performed by a gain adjusting circuit 5 and to minimize the dispersion of the image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared image pickup device having an image correction circuit.

[0002]

2. Description of the Related Art Conventionally, in an infrared image pickup device, a plurality of (for example, four) detecting elements are arranged side by side in a vertical direction, and infrared rays are horizontally projected on the detecting element by a two-dimensional scanning optical system including a plurality of mirror optical systems. It is known that two-dimensional scanning is performed in the vertical direction and a two-dimensional image is displayed on the CTR in synchronization with this scanning. In this type of infrared imaging device, by arranging a plurality of detection elements in the vertical direction, signals corresponding to a plurality of horizontal scanning lines of the CTR are simultaneously obtained by one horizontal scanning of two-dimensional scanning. Will be obtained.

However, it is known that the photoelectric conversion characteristics of each sensing element have slight variations. Also,
Since the reflectance on each mirror surface of the polygon mirror used in the scanning optical system is not constant, the output signal photoelectrically converted into the detection element varies even when the same object is imaged. Therefore, there is a problem that a striped pattern or the like appears on the screen when an image is output, and a clear image cannot be obtained. Therefore, various circuits have been proposed for correcting the variation of the signal of the detection element.

For example, there is provided a circuit for extracting gain information for each element from one or more screens and making the gain values constant. As a specific extraction method, first, the information of the gain information is extracted by a method of cumulatively adding the outputs of the respective elements in the time direction and obtaining the sum. Then, image correction is performed so that the variation in the gain information among the respective detection elements is minimized.

That is, the gain information is obtained by cumulatively adding the maximum / minimum values for each fixed time for each imaged pixel and obtaining the output difference between the maximum / minimum values.

FIG. 2 is a block diagram showing a conventional correction circuit of this type. In the figure, infrared rays from a subject enter an apparatus through an objective lens (not shown), and are two-dimensionally scanned by a two-dimensional scanning optical system (not shown), and enter a plurality of detection elements 51 arranged side by side. The output signal photoelectrically converted by the detection element 51 is input to the offset adjustment circuit 60. The signal whose offset is adjusted by the offset adjustment circuit 60 is
It is input to the gain adjusting circuit 55. The gain adjusting circuit 55 is a circuit that adjusts the variation of the light incident amount-output signal value characteristics of each detecting element to a desired gain value by an observer's adjusting operation as described above. The gain is adjusted by the observer setting a value in the indicating member 540, and the control circuit 54 controls the gain adjusting circuit 55. Next, the adjusted image signal is sent to the image correction arithmetic circuit 52, and the image correction arithmetic circuit 52 corrects the variation for each sensing element.

A synchronization signal is added to the correction output of the image correction calculation circuit 52, and the output I / F circuit 56 changes to a predetermined output format so that the image can be easily observed. An infrared image of the subject is displayed on the CTR monitor 59 by the output of the output I / F circuit 56. The correction coefficient used in the image correction calculation circuit 52 is
The residual variation is detected by the image variation detection circuit 53 which inputs the output of the image correction data, and the new image coefficient data is stored in the correction coefficient memory 57 by the image correction data calculation circuit 58 from this residual variation. The value is used.

Since the correction coefficient calculated in this way is calculated from real-time real image processing information, a plurality of two or more points are used so as to deal with the non-linearity of variations between elements regardless of environmental changes. As compared with the configuration in which the correction coefficient is calculated in advance based on the temperature measurement point of 1 and stored, the result can be obtained with higher accuracy.

The conventional block diagram shown in FIG.
Since the closed-loop configuration performs the gain correction by calculating the variation in the image variation detection circuit 53 with respect to the final output, it is more effective than the configuration in which the correction calculation is performed before the gain adjustment circuit 5.

[0010]

However, in the above-mentioned configuration, when the observer performs the gain / offset adjustment using the control circuit 54, the noise at the time of switching causes
The assumption that uniform infrared light is incident on all the sensing elements is not satisfied, and the image variation detection circuit cannot respond to changes in the measurement situation and shows an abnormal output.
A situation occurs in which image variation correction is not performed normally.

Therefore, an object of the present invention is to solve the problems of the above-mentioned conventional techniques, to eliminate noise at the time of switching when image correction is performed by a gain adjusting circuit, and to minimize image variations. Possible image correction circuit (52, 5
3, 57) to provide an infrared imaging device.

[0012]

In order to achieve the above object, the present invention receives infrared light from an object by a plurality of detection elements, and a photoelectric conversion electric signal at the detection elements is gained by a gain adjusting circuit. The image forming means for generating a two-dimensional image on the basis of the adjusted signal and displaying it on the display and the gain adjusting circuit are connected in the subsequent stage, and the correction coefficient is calculated from the variation of the output value for each sensing element and stored. In an infrared imaging device equipped with an image correction circuit that corrects variations based on stored values, the operation of the image correction circuit is stopped when the gain is switched, and the stored value before the switching operation is multiplied by the gain to correct the variations. It is an infrared imaging device provided with a circuit.

In this case, it is preferable that the image correction circuit clears the data of the variation in the output value from the actual image obtained by the time of switching the gain when switching the gain.

Further, the image correction circuit preferably holds the correction coefficient memory data before the gain switching operation as internal data.

[0015]

According to the present invention, since a predetermined correction coefficient is rewritten in the gain adjusting circuit, the gain variable can be changed without using the correction coefficient calculated based on the data before and after the variable when the gain is changed. Occasionally, it is possible to prevent unnecessary and inappropriate correction data from being taken in by taking a measure by multiplying the already-calculated correction data before variable by the gain.

At the time of variable offset, the data acquisition is stopped until the variable offset is stopped, and the correction data calculated before the variable is output to calculate the correction data from the data acquired after the variable offset is stopped.
It is also possible to use a new correction coefficient. By these actions, it is possible to reduce the occurrence of uneven correction of the image when the gain is switched.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an infrared image pickup device having an image correction circuit according to the present invention will be described below with reference to FIG. The detection element 1 receives infrared rays from a subject incident from an optical system (not shown). The electric signal obtained by photoelectric conversion in the detection element 1 is offset-adjusted by the offset adjustment circuit 10 controlled by the control circuit 4, and then input to the gain adjustment circuit 5. The indicator member 40 is operated by an observer, and the indicator member 40 indicates a gain and an offset value, whereby the offset adjustment circuit 1 is controlled via the control circuit 4.
0 and the offset value and gain of the gain adjusting circuit 5 are set.

The output signal of the gain adjustment circuit 5 is input to the image correction calculation circuit 2, and the image correction calculation circuit 2 corrects the variation of each element. Then, the image signal subjected to the variation correction is input to the output I / F circuit 6. In the output I / F circuit 6, the observer can arbitrarily set a desired image, and the signal set in this way is changed to a predetermined TV video signal by adding a synchronizing signal to the CT,
It is output to the monitor 9 composed of R.

At this time, the gain correction data and the offset correction data for each element are stored in the correction coefficient memory 7, and the gain correction data and the offset correction data are output to the image correction arithmetic circuit 2 and the image correction arithmetic circuit is output. In 2, image correction can be performed by multiplying and adding the element outputs from the offset adjustment circuit 10 and the gain adjustment circuit 5.

On the other hand, an image variation detection circuit 3 is connected to the subsequent stage of the image correction calculation circuit 2. The image variation detection circuit 3 is composed of, for example, a circuit that takes in all image data in a corrected image for a certain period of time and extracts gain information and offset information for each detection element from the data.
The image variation detection circuit 3 detects the residual variation in the output signal corrected by the image correction calculation circuit 2, and the image correction data calculation circuit 8 calculates new image coefficient data according to the residual variation amount. Write data to the coefficient memory 7 is calculated.

In the following, the image variation detection circuit 3
And the relationship with the image correction data calculation circuit 8 will be described. The image variation detection circuit 3 and the image correction data calculation circuit 8 are controlled by the operation command of the control circuit 4 in association with the adjustment of the offset adjustment circuit 10 and the gain adjustment circuit 5.

In this embodiment, the image variation detecting circuit 3 is
As described above, the gain information and the offset information for each sensing element can be extracted from the image correction arithmetic circuit 2 at a predetermined timing, but when the gain / offset is variable, the extraction is stopped and stored inside itself. Keep clearing the gain information. In addition, the image correction data calculation circuit 8
Then, the correction coefficient for both the gain and the offset for each detection element is calculated based on the gain information and the offset information for each detection element. However, when the gain is variable, the correction coefficient is stored based on the signal from the control circuit 4. 7, a new correction coefficient is calculated by multiplying the gain change amount as a multiple, and is stored in the correction coefficient memory 7 again. When the time necessary for the gain adjustment to stabilize elapses, the original sequence is restored again, and the control circuit 4 causes the image variation detection circuit 3 and the image correction data calculation circuit to perform the original operation. Control eight.

It is also possible to set a modified example in which the image correction arithmetic circuit 2 is arranged before the offset adjusting circuit 10 in the above-mentioned configuration. In this case, it is not necessary to multiply the correction data by the gain change amount as a multiple when the gain is changed, and output it. Do not import. This makes it possible to prevent unstable data capture when the gain / offset is changed. Further, in the above-described embodiments, for example, four detecting elements are arranged side by side and the image is two-dimensionally scanned on the detecting elements. However, the present invention limits the subject. As a result, it can be used even when a two-dimensional image pickup device (CCD or the like for electrically scanning) is used.

[0024]

As is apparent from the above description, according to the present invention, when the gain is switched, the image variation for each detecting element is corrected by the predetermined correction data to prevent the occurrence of the image unevenness. There is an effect that it is possible to reduce the number and obtain a high quality image.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of an infrared imaging device including an image correction circuit according to the present invention.

FIG. 2 is a schematic block diagram showing an example of an infrared image pickup device including a conventional image correction circuit.

[Explanation of symbols]

 1 Detection Element 2 Image Correction Calculation Circuit 3 Image Variation Detection Circuit 4 Control Circuit 5 Gain Adjustment Circuit 7 Correction Coefficient Memory 8 Image Correction Data Calculation Circuit 10 Offset Adjustment Circuit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Taijiro Kiyota 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation

Claims (3)

[Claims] 1. An infrared light from an object is received by a plurality of detection elements, a photoelectric conversion signal at the detection elements is gain-adjusted by a gain adjustment circuit, and a two-dimensional image is generated on the basis of the signal to be displayed on a display. An image correction circuit that is connected to a visualization unit for displaying and a stage subsequent to the gain adjustment circuit, calculates and stores a correction coefficient from the variation in the output value of each sensing element, and corrects the variation based on the stored value. In the infrared image pickup device including, a correction circuit that stops the operation of the image correction circuit at the time of switching the gain and corrects the variation by multiplying the stored value before the switching operation by a gain. Characteristic infrared imaging device. 2. The image correction circuit, when the gain is switched, clears data of variation in output value from the actual image obtained by the switching.
An infrared image pickup device comprising the image correction circuit described. 3. An infrared image pickup device having an image correction circuit according to claim 1, wherein said image correction circuit is provided with a holding means for holding correction data before said gain switching operation as internal data.