JP2713196B2 - Signal processing method of multi-element imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing system for a multi-element image pickup apparatus having a linear infrared detector comprising a plurality of infrared detectors.

[0002]

2. Description of the Related Art Conventionally, in an infrared imaging apparatus having a linear multi-element detector, distortion (shading) of the light quantity of an output image caused by the imaging characteristics of the optical system and the non-uniformity of the sensitivity of the detector is eliminated. For this purpose, a shielding plate (calibration plate) is temporarily inserted in front of the optical system of the multi-element detector to input a fixed incident power to each detection element. At this time, the output of each detection element is converted to an offset signal. A signal processing method of correcting an image signal obtained based on the offset signal during normal imaging is used.

However, in the above-described signal processing method, correction data is not obtained by using actual infrared light in an actual imaging environment. When the temperature of the calibration plate (infrared radiation amount) to be imaged and the temperature of the imaging target including the optical path (actual infrared radiation amount) are different, the correction of the image signal is not accurate, and Quality may be impaired.

Therefore, a signal processing system has been proposed in which offset is removed using actual infrared light in an actual imaging environment, as described in Japanese Patent Application Laid-Open No. 4-82278. In the signal processing system described in this publication, the above-mentioned calibration plate is not used, and the correction processing of the image signal is performed as follows.

[0005] Temporarily shifting the focus of the focusing optical system that focuses the incident power on the multi-element detector causes blurring of the optical focus, thereby making the incident power on each detector constant. The output of each detector at this time is defined as an offset signal. At the time of normal imaging, the image signal is corrected based on the offset signal. In this manner, by performing offset removal using actual infrared light in an actual imaging environment including the light condensing optical system, accurate offset correction (removal of shading components) can be performed, and a high-quality image can be provided. Has been realized.

[0006]

However, the signal processing method of the above-mentioned conventional infrared imaging apparatus has the following problems.

Temporarily shielding plate (calibration plate) in front of optical system
In the one that obtains the offset signal by inserting the correction signal, the correction data is not obtained using the actual infrared light in the actual imaging environment, as described above. If the temperature of the inserted calibration plate (the amount of infrared radiation) is different from the temperature of the imaging target including the optical path (the actual amount of infrared radiation), the correction of the image signal will not be accurate, and There is a problem that the quality of the product is impaired.

In a system in which the focus of the condensing optical system is temporarily shifted to cause an optical focus to be blurred and an offset signal is obtained, the case where the apparatus environment is different from the temperature of the imaging object or the temperature of the inserted calibration plate Although the correction of the image signal can be made accurate when the (infrared radiation amount) and the imaging target temperature (actual infrared radiation amount) including the optical path are different, there are the following problems. .

In the above-described signal processing method, since the image is corrected based on the offset data obtained before the start of imaging, factors that affect the offset level, such as the temperature of the condensing optical system, change during imaging. However, a change in the offset level accompanying the change is not reflected in the offset data. For this reason, the offset data is inaccurate due to the change in the offset level due to the imaging environment temperature, and accurate image signal correction cannot be performed. In such a case, the imaging is temporarily interrupted, and the offset data is retaken. As described above, in the signal processing method in which the image signal is corrected based on the offset data obtained before the start of the imaging, an accurate image is obtained when the temperature of the light collecting optical system (imaging environment temperature) changes during the imaging. There is a problem that signal correction (removal of shading components) cannot be performed and image quality is impaired. in addition,
If the temperature or the like of the light condensing optical system (imaging environment temperature) changes during imaging, the imaging must be temporarily interrupted and offset data must be retaken. Therefore, continuous imaging cannot be performed, and it takes time to perform imaging. There is a problem.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a signal processing method of a multi-element image pickup apparatus capable of reflecting a change in an offset level accompanying a change in a temperature of a light-collecting optical system during image pickup (temperature of an image pickup environment) in offset data.

[0011]

The signal processing method of the multi-element image pickup apparatus according to the present invention comprises a line-shaped infrared detector comprising a plurality of infrared detection elements and an infrared light from an object to be imaged. a signal processing method of the multi-element imaging device having a focusing optical system that allowed to enter the infrared detector, the line-shaped infrared
The image signal output from the detector is divided into a plurality of lines per line.
Storage means for storing the data stored in the storage means;
The image signals of several lines are detected by the linear infrared detector.
The averaged image is obtained by adding and averaging for each output of the output element.
By subjecting the signal to low-pass filtering,
Shade to extract shading components related to optical optics
A shading component extracting means, and the shading from the image signal.
Shading extracted by the shading component extraction means
And shading component removing means for removing components .

[0012]

Further, the shading component removing means includes:
The signal of only the shading component extracted by the shading component extraction means is used as a reference signal, and the reference signal is compared with the image signal output from the linear infrared detector to remove the shading component from the image signal. It may be performed.

Further, a means for correcting the sensitivity of each detection element by multiplying the image signal from which the shading component has been removed by the shading component removal means by the reciprocal data of the sensitivity deviation of each detection element of the linear infrared detector. It may be provided.

[0015]

Normally, in a multi-element image pickup device in the infrared region, the magnitude of shading with respect to the condensing optical system is considerably larger than the image signal level. In the signal processing method of the multi-element imaging device according to the present invention, a shading component relating to the light-collecting optical system is directly extracted from an image signal detected by the linear infrared detector. The extraction of the shading component is constantly performed during the imaging, and the image signal is corrected based on the extracted shading component. Therefore, when the offset level related to the removal of the shading component changes due to a change in the temperature of the condensing optical system or the like, the change in the offset level is reflected in the extracted shading component. As described above, according to the present invention, since the image signal is corrected based on the shading component reflecting the change in the offset level due to the temperature change of the light collecting optical system or the like, the temperature of the light collecting optical system or the like during imaging is reduced. Even if the imaging environment temperature changes, the image signal can be accurately corrected without deteriorating the image quality as in the related art.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a circuit using a signal processing system of a multi-element image pickup apparatus according to one embodiment of the present invention.

In FIG. 1, 1 is a multi-element infrared detector arranged in a line, 2 is a preamplifier, 3 and 12 are amplifiers, 4 and 13 are sample and hold circuits, 5 and 14 are A / D converters, 6 and 10 are memories, 7 is an arithmetic processing circuit, 8 is a ROM, 9 is a multiplier, 11 is a D / A converter, and 15 is a data formatter. These components are configured as follows.

The multi-element infrared detector 1 is disposed at a light-collecting position of a light-collecting optical system (not shown), and detects infrared light from an object to be imaged through the light-collecting optical system. . The incident power from the imaging object and the heat radiation power from the condensing optical system itself are incident on the multi-element infrared detector 1 via the condensing optical system.

The preamplifier 2 receives each output of the multi-element infrared detector 1 as an input, and outputs the output of each detector input in time series to each of the amplifiers 3 and 12.

The amplifier 3 amplifies each output of the multi-element infrared detector 1 output from the preamplifier 2, and the output is sequentially transmitted to the sample-and-hold circuit 4, A / D converter 5, and memory 6. The data is input to the arithmetic processing circuit 7 via Here, the sample hold circuit 4 holds the output of the amplifier 3, the A / D converter 5 converts the held output of the amplifier 3 from analog to digital, and the memory 6 stores the analog / digital conversion. The output of the amplifier 3 is stored for each line of the multi-element infrared detector 1. In this embodiment, the memory 6 stores data for a plurality of lines.

The arithmetic processing circuit 7 extracts a shading component relating to the light collecting optical system from the image signal output from the multi-element infrared detector 1. This arithmetic processing circuit 7
Then, the data for a plurality of lines accumulated in the memory 6 is averaged for each output of each detection element of the multi-element infrared detector 1, that is, for each same pixel signal, and the averaged data is subjected to a low-pass filter. By performing the processing, the shading component caused by the heat radiation power incident on the multi-element infrared detector 1 from the above-described light-converging optical system is extracted. The output of the arithmetic processing circuit 7 is output to the memory 10 and the D / A
The sample and hold circuit 1 described above is sequentially passed through the converter 11.
3 has been entered. Here, the memory 10 stores the output of the arithmetic processing circuit 7, and the D / A converter 11 performs D / A conversion of the data stored in the memory 10.

The amplifier 12, like the amplifier 3, amplifies the output of the preamplifier 2. The output of the amplifier 12 is input to the sample and hold circuit 13. The sample-and-hold circuit 13 is a means for removing the above-mentioned shading component from the image signal. The output of the amplifier 12 is used as one input, and the shading data output from the D / A converter 11 is used as reference data for the other. Input and D
The output (image signal) of the preamplifier 12 is corrected based on the shading data output from the / A converter 11. The output of the sample and hold circuit 13 is A
After being digitally processed by the / D converter 14, it is input to the multiplier 9.

The multiplier 9 is a means for correcting the sensitivity of the detecting element. The output of the A / D converter 14 is used as one input, and a constant incident power is applied to the other input. A ROM 8 in which reciprocal data of the sensitivity deviation obtained by calculating the deviation of the variation of the sensitivity data of each detector when the light is incident on the detector 1 is connected. In this multiplier 9, A
The sensitivity deviation data recorded in the ROM 8 is multiplied by the shading corrected data input from the / D converter 14. The output of the multiplier 9 is sent to another signal processing unit (not shown) via the data formatter 15. Here, the data formatter 15 applies a predetermined data format to the signal when transmitting the signal to a signal processing system (not shown) connected to the output stage of the circuit using the signal processing method of the present invention. is there.

Next, the operation of the signal processing circuit of the multi-element imaging device configured as described above will be described with reference to FIGS.

FIGS. 2 to 5 show each of the sample-and-hold circuit 4, the arithmetic processing circuit 7, the multiplier 9, and the sample-and-hold circuit 13 when a constant incident power is applied to the multi-element infrared detector 1. In the waveform diagram showing the output, the vertical axis represents the output level or the amount of incident light, and the horizontal axis represents the position (detector No.) of each detection element of the multi-element infrared detector 1.

When infrared light from an object to be imaged enters the multi-element infrared detector 1 through a condensing optical system (not shown), the multi-element infrared detector 1 passes through the upper preamplifier 2 to each of the detection elements. Pixel signals are output to the amplifiers 3 and 12 in time series.

Each pixel signal is input to the amplifier 3 in a time-series manner, and when the signal is amplified by the amplifier 3, an image signal as shown in FIG. A signal corresponding to one line obtained by adding a signal in which the output of the detector becomes low and a signal corresponding to the incident power from the imaging target to which a sensitivity deviation of each detector is added is output. The signal output from the sample and hold circuit 4 is supplied to an A / D converter 5
Are A / D converted and stored in the memory 6. When the image signals for a plurality of lines are stored in the memory 6 in this manner, the stored image signals for the plurality of lines are sent to the arithmetic processing circuit 7.

When image signals for a plurality of lines are sent from the memory 6 to the arithmetic processing circuit 7, the arithmetic processing circuit 7 averages the input image signals for the plurality of lines, and outputs the averaged image signal. Is subjected to low-pass filtering,
From the signal shown in FIG. 2, a signal of only a shading component caused by the heat radiation power incident on the multi-element infrared detector 1 from the condensing optical system, that is, detectors located at both ends as shown in FIG. The shading signal whose output is low is extracted. The offset correction data generated by the arithmetic processing circuit 7 is temporarily stored in the memory 10, D / A converted by the D / A converter 11, and input to the sample and hold circuit 13 as a reference signal.

When the offset correction data is input to the sample and hold circuit 13 as a reference signal, the sample and hold circuit 13 corrects each pixel signal output from the amplifier 12 based on the offset correction data. As a result, as shown in FIG. 4, a signal in which the sensitivity deviation of each detection element is applied to the image signal according to the incident power from the imaging target, which is not affected by the shading component, is output from the sample and hold circuit 13. . The signal output from the sample and hold circuit 13 is A / D converted by the A / D converter 14 and input to the multiplier 9.

The multiplier 9 adds the image signal to the ROM 8
Is multiplied by the reciprocal data of the sensitivity deviation, and an image signal is output according to the incident power from the imaging target, which is not affected by the shading component and the sensitivity deviation of each detection element as shown in FIG. The signal output from the multiplier 9 is subjected to a predetermined data format by the data formatter 15 and then sent to a signal processing system (not shown).

As described above, in the present embodiment, the shading component is extracted from the image signal detected by the multi-element infrared detector 1 for each of a plurality of lines.
Offset data reflecting a change in the offset level due to a temperature change in the optical system or the like (a change in the imaging environment temperature) is obtained, real-time image signal correction is performed, and high-quality images are provided.

In the above-described signal processing method of the multi-element image pickup apparatus of the present embodiment, the extraction of the shading component in the arithmetic processing circuit 7 is performed for each of a plurality of lines.
The offset data for correcting the image signal is updated every plural lines, but the present invention is not limited to this. For example, the offset data is updated according to a temperature change of the optical system. You may make it.

Further, in the present embodiment, the data measured at a predetermined environmental temperature is used to create the sensitivity deviation data stored in the ROM 8, but the data measured at a plurality of environmental temperatures is used. The reciprocal data of the sensitivity deviation at a plurality of environmental temperatures is created, and the multiplication unit 9 multiplies the signal after the shading correction by the reciprocal data of the sensitivity deviation in accordance with a temperature change of the optical system. You may. By doing so, the quality of the image is further improved.

[0035]

Since the present invention is configured as described above, it has the following effects.

According to the first, second and third aspects, the image signal is corrected based on the shading component on which the change of the offset level due to the temperature change of the condensing optical system is reflected. In addition, even when the temperature of the light collecting optical system or the like (imaging environment temperature) changes during imaging, there is an effect that the image signal is accurately corrected and imaging can be performed continuously.

According to the fourth aspect of the present invention, since the image signal is corrected in consideration of the sensitivity deviation of each detection element of the linear infrared detector, the image quality due to the difference in the sensitivity of each detection element is adjusted. This has the effect of preventing deterioration and providing a good image.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a signal processing circuit of a multi-element imaging device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing an output of a sample and hold circuit 4.

FIG. 3 is a waveform chart showing an output of the D / A converter 11.

FIG. 4 is a waveform chart showing an output of the sample hold circuit 13.

FIG. 5 is a waveform diagram showing the contents of output data of a multiplier 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multi-element infrared detector 2 Preamplifier 3, 12 amplifier 4, 13 Sample hold circuit 5, 14 A / D converter 6, 10 Memory 7 Operation processing circuit 8 ROM 9 Multiplier 11 D / A converter

Claims (3)

(57) [Claims] 1. A multi-element imaging apparatus comprising: a linear infrared detector including a plurality of infrared detection elements; and a condensing optical system that causes infrared light from an imaging target to enter the linear infrared detector. This is a signal processing method of the apparatus, wherein an image signal output from the linear infrared detector is one line.
Storage means for storing a plurality of lines each in an image signal for a plurality of lines stored in said storage means before
Addition is made for each output of each detection element of the linear infrared detector.
Averaging and low-pass filtering the averaged image signal
Is performed, the shade related to the condensing optical system is
A shading component extracting unit for extracting a shading component, and the shading component extracting unit from the image signal.
Shade that removes the extracted shading components
Signal processing method of the multi-element imaging apparatus characterized by comprising: a ring component removing means. 2. The signal of the multi-element imaging device according to claim 1.
In the processing method, the shading component removing means
Is the system extracted by the shading component extraction means.
A signal containing only the edging component is used as a reference signal, and the reference signal
Signal and the image signal output from the linear infrared detector.
By comparing the shading components from the image signal
A signal processing method for a multi-element imaging device, comprising: 3. The multi-element according to claim 1, wherein
In the signal processing method of the imaging apparatus, shading is performed by the shading component removing unit.
Each of the linear infrared detectors
Multiply the reciprocal data of the sensitivity deviation of the detector to detect each
A signal processing method for a multi-element imaging device, comprising: means for correcting the sensitivity of an element. "