JPH0761133B2 - Offset correction circuit and fixed pattern noise data correction circuit for infrared imaging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention removes fixed pattern noise data (digital data) representing fixed pattern noise from infrared image data (digital data) representing an infrared image in an infrared image signal from an infrared imaging device. The present invention relates to an offset correction circuit for an infrared imaging device. The present invention also relates to a fixed pattern noise data correction circuit which is used in an offset correction circuit for an infrared imaging device and corrects fixed pattern noise data.

[0002]

2. Description of the Related Art As shown in FIG. 2, a conventional offset correction circuit for an infrared image pickup device turns on image data when a uniform temperature distribution of a surface light source or the like is observed by a changeover switch 7 that is turned on.
Via the integrator 6, which integrates the received image data several times and outputs random noise-removed data as fixed pattern noise data, and fixed pattern noise data as stored noise data. FPN
(Fixed pattern noise) data memory 3 and infrared image data from which fixed pattern noise data should be removed are received via a latch L, the stored noise data is subtracted from the received infrared image data, and the subtraction result Of the infrared image data (FPN) from which the fixed pattern noise data has been removed.
And a difference calculator 1 for outputting as removal data).

In this conventional offset correction circuit, first, image data when a uniform temperature distribution of a surface light source or the like is observed is integrated several times by an integrator 6 and random noise is removed. Is written in the FPN data memory 3. Next, this data is used as the difference calculator 1
The fixed pattern noise was removed by subtracting from normal infrared image data.

For example, Japanese Patent Application Laid-Open No. 2-121480 discloses that image signal is corrected by subtracting fixed pattern noise from the image signal.

[0005]

In the offset correction circuit shown in FIG. 2, the A / D provided before the offset correction circuit is used.
Quantization error when converting analog image data into digital image data by the converter, circuit noise in this offset correction circuit, and signal when fetching fixed pattern noise data into the FPN data memory 3. There may be a case where fixed pattern noise of about several LSBs remains due to fluctuation of the image.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an offset correction circuit for an infrared image pickup device which can remove fixed pattern noise with high accuracy.

Another object of the present invention is to provide a fixed pattern noise data correction circuit which is used in an offset correction circuit for an infrared image pickup device and which corrects fixed pattern noise data and outputs highly accurate corrected noise data. To provide.

According to the present invention, there is provided an offset correction circuit for an infrared image pickup device for removing fixed pattern noise data representing fixed pattern noise from infrared image data representing an infrared image, wherein a uniform temperature distribution of a surface light source or the like is obtained. An integrator that integrates image data at the time of viewing several times and outputs data from which random noise is removed as the fixed pattern noise data, and a fixed unit that stores the fixed pattern noise data as stored noise data. In the offset correction circuit for an infrared imaging device having a memory for pattern noise data, the image data and the stored noise data when a uniform temperature distribution of the surface light source or the like is observed are compared pixel by pixel and the difference is obtained. Outputs the calculation result obtained by calculating the data and integrating it as fixed pattern noise correction data with a sign. A comparison calculation unit, a fixed pattern noise correction data memory that stores the fixed pattern noise correction data with the sign as stored noise correction data, and the stored noise correction data in the stored noise data. An adder that adds with a sign and outputs the addition result, and a difference operation that subtracts the addition result from the infrared image data and outputs the subtraction result as infrared image data from which the fixed pattern noise data is removed And an offset correction circuit for an infrared image pickup device.

Further, according to the present invention, the fixed pattern noise data is corrected by being used in an offset correction circuit for an infrared image pickup device for removing fixed pattern noise data representing fixed pattern noise from infrared image data representing an infrared image. Then, in the fixed pattern noise data correction circuit that outputs the corrected noise data, the image data when a uniform temperature distribution of a surface light source or the like is observed is integrated several times, and the data from which random noise is removed is An integrator that outputs fixed pattern noise data, a memory for fixed pattern noise data that stores the fixed pattern noise data as stored noise data, and the image when viewing a uniform temperature distribution of the surface light source or the like. The data and the stored noise data are compared pixel by pixel to obtain difference data and obtained by integrating several times. The operation result a comparing unit for outputting a fixed pattern noise correction data with a sign,
This fixed pattern noise correction data with a sign, a fixed pattern noise correction data memory that stores as stored noise correction data, and the stored noise correction data is added to the stored noise data with a sign, A fixed pattern noise data correction circuit is provided, which comprises: an adder that outputs the addition result as the corrected noise data.

[0010]

The present invention will be described below with reference to the drawings.

Referring to FIG. 1, an offset correction circuit for an infrared imaging device according to an embodiment of the present invention includes a fixed pattern noise data correction circuit for correcting fixed pattern noise data and outputting the corrected noise data. . This fixed pattern noise data correction circuit receives image data when a uniform temperature distribution of a surface light source or the like is being observed, through the switch 7 in the ON state, integrates the received image data several times, and generates random noise. The removed data is received via the integrator 6 that outputs the fixed pattern noise data, the FPN data memory 3 that stores the fixed pattern noise data as the stored noise data, the latch L, and the changeover switch 8. , The stored noise data received from the FPN data memory 3 via the change-over switch 9 while comparing the image data when a uniform temperature distribution of the surface light source or the like is observed, and the difference is obtained by comparing each pixel. A comparison calculation unit 2 that outputs the calculation result obtained by obtaining the data and integrating the data several times as fixed pattern noise correction data with a sign.
And the fixed pattern noise correction data with this sign,
The FPN (fixed pattern noise) correction data memory 4 to be stored as the stored noise correction data, and the stored noise data received from the FPN data memory 3 via the changeover switch 9 to the stored noise correction An adder 5 that adds data with a sign and outputs the addition result as the corrected noise data is provided.

The offset correction circuit for infrared imaging apparatus further includes the addition result (that is, from the infrared image data received from the latch L, the changeover switch 8 and the latch L from which fixed pattern noise data should be removed). The corrected noise data) is subtracted, and the subtraction result is the infrared image data (FPN) from which the fixed pattern noise data is removed.
The difference calculator 1 for outputting as removal data) is provided.

In this offset correction circuit, first, a control signal for capturing fixed pattern noise is input from the outside while receiving a uniform temperature distribution of a surface light source or the like. When the changeover switch 7 is closed by the control signal, the integrator 6 takes in and integrates the image data any number of times to generate data in which random noise is removed. This data is stored in the FPN data memory 3 as fixed pattern noise data.

Next, the changeover switches 8 and 9 are changed over to the A side, and the image data in a state where the surface light source or the like is receiving a uniform temperature distribution and the fixed pattern noise data output from the FPN data memory 3 are set to one pixel. The comparison calculation unit 2 compares the values one by one and obtains the difference. This is performed an arbitrary number of times and the averaged value is stored as a fixed pattern noise correction data for each pixel in the FPN correction data memory 4 with a code.

Next, the changeover switches 8 and 9 are switched to the B side, and the fixed pattern noise correction data output from the FPN correction data memory 4 is added to the fixed pattern noise data output from the FPN data memory 3 by the adder 5. Add with sign.

Finally, the adder 5 is added from the infrared image data from which the normal fixed pattern noise data should be removed by the difference calculation unit 1.
The FPN removal data is obtained by subtracting the output of

[0017]

As described above, according to the present invention, the residual fixed pattern noise of about several LSB, which cannot be completely removed by the conventional technique, is eliminated by the quantization error during A / D conversion and the offset correction circuit. It is possible to obtain a highly accurate offset correction circuit for an infrared imaging device that can be removed without being affected by circuit noise and signal fluctuations when capturing fixed pattern noise data into a fixed pattern noise data memory.

Further, according to the present invention, the quantization error at the time of A / D conversion, the circuit noise in the offset correction circuit, and the fluctuation of the signal at the time of fetching the fixed pattern noise data into the fixed pattern noise data memory. A fixed pattern noise data correction circuit that outputs highly accurate corrected noise data in which the residual fixed pattern noise component due to the above is removed is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an offset correction circuit for an infrared imaging device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional offset correction circuit for an infrared imaging device.

[Explanation of symbols]

 1 Difference Calculation Unit 2 Comparison Calculation Unit 3 FPN Data Memory 4 FPN Correction Data Memory 5 Adder 6 Integrator 7 Changeover Switch 8 Changeover Switch 9 Changeover Switch L Latch

Claims (2)

[Claims] 1. An offset correction circuit for an infrared imaging device, which removes fixed pattern noise data representing fixed pattern noise from infrared image data representing an infrared image, when a uniform temperature distribution of a surface light source or the like is observed. For integrating the image data of several times and outputting the data from which random noise is removed as the fixed pattern noise data, and the fixed pattern noise data for storing the fixed pattern noise data as the stored noise data. In the offset correction circuit for an infrared image pickup device having a memory, the image data and the stored noise data when a uniform temperature distribution of the surface light source or the like is observed are compared pixel by pixel to obtain difference data. The calculation result obtained by integrating twice,
A comparison calculation unit that outputs signed fixed pattern noise correction data with a sign, a fixed pattern noise correction data memory that stores the signed fixed pattern noise correction data as stored noise correction data, and the stored noise The stored noise correction data is added to the data with a sign and an addition result is output, and the addition result is subtracted from the infrared image data, and the subtraction result is removed from the fixed pattern noise data. An offset correction circuit for an infrared imaging device, comprising: a difference calculator that outputs the infrared image data. 2. An infrared image pickup device offset correction circuit for removing fixed pattern noise data representing fixed pattern noise from infrared image data representing an infrared image,
In the fixed pattern noise data correction circuit that corrects the fixed pattern noise data and outputs the corrected noise data, the image data when a uniform temperature distribution such as a surface light source is observed is integrated several times to eliminate random noise. An integrator that outputs the removed data as the fixed pattern noise data, a memory for the fixed pattern noise data that stores the fixed pattern noise data as the stored noise data, and a uniform temperature distribution of the surface light source or the like. The calculation result obtained by comparing the image data at the time of viewing and the stored noise data pixel by pixel to obtain difference data and integrating several times,
A comparison calculation unit that outputs signed fixed pattern noise correction data with a sign, a fixed pattern noise correction data memory that stores the signed fixed pattern noise correction data as stored noise correction data, and the stored noise A fixed pattern noise data correction circuit, comprising: an adder that adds the stored noise correction data to the data with a sign and outputs the addition result as the corrected noise data.