JPH1062257A - Automatic pixel defect correction device for infrared two-dimensional sensor camera system - Google Patents

Abstract

(57) [Summary] [Problem] To automatically correct image data by defective pixels in an infrared two-dimensional sensor camera system. A two-dimensional sensor unit includes a lens.
, A two-dimensional thermal image of the uniform average heat source 6 as a subject for correction is captured, and the captured data is stored in the frame memory 3 under the control of the CPU 4 connected to each component via the bus line. You. CPU 4 is a frame memory 3
Out of the frame-by-frame imaging data stored in the storage unit, the low-sensitivity data that does not exceed a predetermined threshold is extracted as a defective pixel, and its correction value and address are sent to the defect correction / sensitivity correction circuit 2 to perform defect correction. And a correction of output irregularity at a predetermined temperature (offset correction)
A temperature output difference correction (gain correction) is performed and stored in the frame memory 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic pixel defect correction apparatus in an infrared two-dimensional sensor camera system, and more particularly to an infrared ray two-dimensional sensor camera system capable of automatically correcting a defective pixel having a pixel sensitivity equal to or lower than a predetermined threshold. The present invention relates to an automatic pixel defect correction device in a three-dimensional sensor camera system.

[0002]

2. Description of the Related Art In a two-dimensional infrared sensor camera system for generating a two-dimensional thermal image of a subject, for example, (horizontal) 16
An infrared two-dimensional sensor having an array of 0 × (vertical) 120 sensors is used. However, since the output of each infrared sensor has variations due to individual differences, if the infrared sensor output is displayed as it is, the variation between pixels will occur.Therefore, there is a built-in correction function to make the variation at the time of display uniform. And adjusted before shipping. As the correction for ensuring the uniformity of the thermal image, there are an offset correction for correcting an offset value based on an irregular output of each infrared detection element at a predetermined temperature and a difference between outputs of the infrared detection elements at two high and low temperatures. That is, gain correction is performed to correct irregularities in gain.

[0003] The above-described offset correction and gain correction are performed as a correction of variation in pixel sensitivity among a number of infrared sensors including an infrared two-dimensional sensor, even if there is no defective pixel. However, if the pixel sensitivity of a certain infrared sensor is lower than a predetermined threshold and is significantly lower than the pixel sensitivity of another infrared sensor and the pixel is defective, the defective pixel corresponding to the defective pixel included in the captured two-dimensional thermal image is used. A correction value for executing the above-described offset correction and gain correction without deterioration must be given to the pixel address. For this reason, it is necessary to check the extraction of defective pixels that do not exceed the threshold not only before shipment but also at any time in response to aging. Conventionally, such pixel defect correction is performed manually.

FIG. 2 is an explanatory diagram of a conventional pixel defect correction operation. The two-dimensional sensor camera system has a built-in processing function for pixel defect correction, and correction processing is performed by pressing a key for correction. In this case, as shown in FIG. 2, a defective pixel on the thermal image 101 with the uniform planar heat source as a subject is visually confirmed, the cursor 102 is aligned with the confirmed pixel, and a key for correction is pressed. The address storage of the defective pixel and its correction have been performed.

[0005]

The pixel defect in the above-described conventional infrared two-dimensional sensor camera system is such that the defective pixel is visually checked, and the correction process is performed by a manual operation. And lack of quickness.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic pixel defect correction apparatus for an infrared two-dimensional sensor camera system which solves the above-mentioned problems and ensures the accuracy and speed of defective pixels.

[0007]

The present invention has the following means in order to achieve the above object. The device of the present invention is an automatic pixel defect correction device of an infrared two-dimensional sensor camera system, wherein a defective pixel which is the origin of an image defect included in two-dimensional thermal image data captured by an infrared two-dimensional sensor with a uniform planar heat source as a subject, First correction means for extracting based on the identification of a pixel whose pixel sensitivity is equal to or lower than a predetermined threshold, and automatically setting a correction value for the extracted defective pixel to eliminate the influence of the defective pixel; And a second correction means for automatically performing offset correction and gain correction for all pixels after correction by the correction means, and performing correction for ensuring uniformity of image quality of the captured two-dimensional thermal image. Having.

Further, the apparatus of the present invention has a configuration in which the correction value by the first correction means is set as an average value of the pixel sensitivities of the four pixels above, below, and left and right of the extracted defective pixel.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Conventional automatic pixel defect correction in an infrared two-dimensional sensor camera system is based on the premise that a defective pixel is specified visually by an operator, and a correction function built in the system is applied to the pixel address of the specified defective pixel. Has been driven and executed by manual operation, so that there has been a problem that accuracy and speed of correction are lacking.

According to the present invention, the image address of the defective pixel is automatically specified by examining the image data of the frame memory storing the acquired two-dimensional thermal image, and the correction value corresponding to the defective pixel is automatically set. In the embodiment, after the offset correction and the gain correction are performed, the accuracy and speed of the correction for securing uniformity in image generation are significantly increased.

[0011]

Next, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. The embodiment shown in FIG.
A two-dimensional sensor unit 1 arranged in a two-dimensional manner and combined with an output circuit such as a CCD, and a defect correction / sensitivity for correcting a defective pixel in addition to sensitivity correction including offset correction and gain correction for all pixels A correction circuit 2;
A frame memory 3 for storing the two-dimensional thermal pixel data acquired by the two-dimensional sensor unit 1 in a predetermined frame unit
A correction program for offset correction and gain correction for all pixels and a program for calculating a correction value for defective pixels are built in, and the correction control for the defect correction / sensitivity correction circuit 2 is performed. C that connects to each component via a bus line and controls the overall operation
FIG. 1 also shows a uniform planar heat source 6 that includes a PU 4 and a lens 5 and provides a uniform heat distribution subject for correction to the two-dimensional sensor unit 1 via the lens 5.

The first correction is a correction for a pixel defect corresponding to a defective pixel included in the two-dimensional thermal image data. Two-dimensional thermal image data obtained by imaging a uniform planar heat source as a subject providing a uniform planar heat distribution, such as a couple checker, with the lens 5 and the two-dimensional sensor unit 1 is transmitted to the frame memory 3 under the control of the CPU 4 via the bus line. Is stored in frame units. The CPU 4 stores the frame memory 3
For the two-dimensional thermal image data for each frame unit stored in the pixel address, a pixel address having a pixel sensitivity not exceeding a predetermined threshold is specified as a defective pixel, and pixel sensitivities of four pixels before, after, left and right of the defective pixel are determined. Find the average value of
This is set as a correction value representing an estimated pixel sensitivity that should be present, and this correction value is supplied to the defect correction / sensitivity correction circuit 2 together with the pixel address of the defective pixel to correct the pixel defect with respect to the input from the two-dimensional sensor unit 1. Make it possible.

The second correction is a correction of sensitivity variations among the individual infrared sensors included in the two-dimensional sensor unit 1. Since this correction is performed subsequently to the above-described first correction, the accuracy of the correction is significantly increased. This correction is intended for correction of sensitivity variations among the sensor units of the two-dimensional sensor unit 1 and is performed by the CPU.
Is performed by the defect correction / sensitivity correction circuit 2 for the two-dimensional thermal image data in units of frames read out from the frame memory 3 under the control of the built-in program.
The dimensional image data is stored in the frame memory 3.

For offset correction and gain correction itself, for example, a uniform plane heat source capable of obtaining two temperatures of low and high temperatures is prepared, and a predetermined number of frames in which a uniform plane thermal image for each temperature is defocused to the full screen are prepared. Subject to
The gain (slope) and offset (temperature difference) are calculated for each pixel by using low-temperature and high-temperature data obtained from the average value of the central part obtained by cutting the peripheral part of the thermal image from which noise has been removed as reference values. The correction is performed by a known method, such as by using a formula, and writing the correction value for each pixel in a storage medium. In this way, image correction, including automatic pixel defect correction, can be performed significantly more accurately and quickly.

[0015]

As described above, according to the present invention, the infrared rays 2
In a two-dimensional sensor camera system, it is possible to automatically correct thermal image defects corresponding to defective pixels included in the acquired two-dimensional thermal image data for each frame, thereby improving the accuracy and speed of the correction process. Has an effect that can be significantly increased.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of a conventional pixel defect correction operation.

[Explanation of symbols]

 Reference Signs List 1 2D sensor unit 2 Defect correction / sensitivity correction circuit 3 Frame memory 4 CPU 5 Lens 6 Uniform planar heat source

Claims (2)

[Claims] 1. A defective pixel which is a source of an image defect included in two-dimensional thermal image data captured by an infrared two-dimensional sensor with a uniform planar heat source as a subject is extracted based on the identification of a pixel having a pixel sensitivity equal to or lower than a predetermined threshold. A first correction unit for automatically setting a correction value for the extracted defective pixel to perform a correction for eliminating the influence of the defective pixel, and an offset correction for all pixels after the correction by the first correction unit. An automatic pixel defect correction apparatus for an infrared two-dimensional sensor camera system, comprising: a second correction unit for automatically performing gain correction and performing correction for ensuring uniformity of image quality of a captured two-dimensional thermal image. . 2. The infrared ray according to claim 1, wherein the correction value set by the first correction unit is set as an average value of pixel sensitivities of four pixels above, below, and left and right of the extracted defective pixel. Automatic pixel defect correction device for 2D sensor camera system.