JP2001186409A - Image distortion correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image distortion correction device that can easily correct image distortion or the like due to distortion of a line through the use of a memory of a small capacity in a short time even when a center of the lens of tan image pickup camera is deviated from a reference position of an image pickup plane. SOLUTION: An arithmetic section 5 sequentially captures an image signal consisting of a plurality of lines on a screen from a camera 1, writes the signal to a memory 7, and sets a use area in a map area of a ROM8 depending on an offset of a lens center with respect to a reference position of the image pickup plane of the camera 1. Thus, the image signal corresponding to each address of an output image is read from the memory 7 in response to a required shift quantity of each pixel while shifting each address of the output image and the signals are sequentially outputted to a display device 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image distortion correcting apparatus, and more particularly to an apparatus for correcting image distortion or the like due to lens distortion of a camera in an image signal processing apparatus.

[0002]

2. Description of the Related Art When an image is captured using an imaging camera,
The image is distorted according to the distortion of the lens system of the camera. Therefore, when trying to reduce such image distortion, the input signals captured by the camera are sequentially stored in the memory for one screen, and each pixel on the screen is moved to reduce the influence of lens distortion. After the correction, the corrected signal for one screen was output. As a result, the influence of the distortion of the lens system can be removed.

[0003]

However, since all the input signals for one screen are once written in the memory and then the pixels are moved, there is a problem that a long time is required for correction. Another problem is that a large-capacity memory for storing all input signals for one screen is required.
Furthermore, the center of the lens of the imaging camera is the reference position of the imaging surface,
For example, if the center is shifted from the center, the amount of movement of each pixel on the screen must be changed in accordance with the shift, and it is extremely difficult to correct image distortion. The present invention has been made in order to solve such a problem, and it is possible to easily use a small-capacity memory in a short time and easily shift the lens center of an imaging camera with respect to a reference position on an imaging surface. It is an object of the present invention to provide an image distortion correction device that can correct image distortion or the like due to distortion.

[0004]

According to a first aspect of the present invention, there is provided an image distortion correcting apparatus which captures an image signal by an imaging camera having a large number of pixels, moves the pixels, and distort the image due to lens distortion of the camera. In the device for correcting
A memory for storing an image signal captured by an imaging camera, a map ROM for storing a required movement amount of a pixel for each address of an output image as a map, and an image signal of a screen composed of a plurality of lines sequentially captured by the imaging camera And an arithmetic unit for reading image signals corresponding to each address of the output image from the memory and sequentially outputting the read image signals in accordance with the required movement amount of the pixels stored in the map ROM. The map ROM is used by shifting each address of the output image in accordance with the amount of displacement of the center of the lens with respect to the reference position of the imaging surface.

According to a second aspect of the present invention, in the image distortion correcting apparatus of the first aspect, the map ROM stores in advance a necessary movement amount of pixels in a region wider than the output image.

In the image distortion correcting apparatus of the present invention, image signals of a screen composed of a plurality of lines are sequentially fetched into a memory via an imaging camera, and a displacement of a lens center with respect to a reference position of an imaging surface of the imaging camera is calculated. By shifting the respective addresses of the output image accordingly and using the map ROM, the image signals corresponding to the respective addresses of the output image are read from the memory in accordance with the required movement amount of each pixel, and are sequentially output. Therefore, even if the position of the lens center with respect to the reference position of the imaging surface of the imaging camera is deviated due to individual differences of the imaging camera, the map RO is not rewritten without rewriting the map ROM.
By reading the required movement amount of each pixel from M, an image signal corresponding to each address of the output image can be read from the memory. Also, instead of moving pixels after writing all image signals for one screen to the memory, an image corresponding to each address of the output image according to the required movement amount of each pixel from the image signal written to the memory. Since the signal is read and output, the time required for correcting the image distortion can be reduced and the capacity of the memory can be reduced.

In the image distortion correcting apparatus according to the second aspect, the required movement amount of pixels in an area wider than the output image is determined in advance in the map R.
Stored in the OM. For this reason, when using the map ROM by shifting each address of the output image in accordance with the positional shift amount of the lens center with respect to the reference position of the imaging surface of the imaging camera, data loss of the map ROM due to the shift is prevented. be able to.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a configuration of an image distortion correction apparatus according to an embodiment of the present invention. The controller 2 is connected to the imaging camera 1, and the display 3 is connected to the controller 2. Controller 2 is camera 1
, An arithmetic unit 5 connected to the A / D converter 4, and a D / A converter 6 connected between the arithmetic unit 5 and the display 3. are doing. Further, the controller 2 is provided with a memory 7 and a ROM 8 connected to the arithmetic unit 5. Memory 7 is camera 1
To store the image signal captured by the. Further, in the ROM 8, a required movement amount of the pixel for each address of the output image for correcting the distortion of the image due to the lens distortion of the camera 1 is stored in advance as a map. As shown in FIG. 2, the ROM 8 stores in advance the necessary movement amounts of the pixels of the map area 10 wider than the use area 9 of the map data corresponding to the output image.

Next, the operation of the image distortion correcting apparatus according to this embodiment will be described. Note that, as shown in FIG. 2, the influence of the lens distortion of the camera 1 is greater at the peripheral portion of the screen, so that the amount of movement of the pixels required for correcting the lens distortion is also greater. As shown in FIG. 3, when the lens center O1 of the camera 1 and the reference position (center) O2 of the imaging surface 11 match, as shown in FIG.
The use area 9 is set at the center of the map area 10 of FIG.
The coordinates of the point P0 at the upper left corner of the use area 9 in the map area 10 at this time are (x0, y0).

[0010] The image signal of the line at the upper end of the screen is sequentially taken in by the camera 1, A / D converted by the A / D converter 4, and then written into the memory 7 via the arithmetic unit 5. Next, the image signal of the second line is fetched from the upper end of the screen, and similarly, the image signal of the lower line is sequentially fetched and written into the memory 7.

The arithmetic unit 5 stores the required movement amount of each pixel in the up-down and left-right directions (+ below and-above) in the use area 9 of the ROM 8 in order to correct image distortion due to lens distortion of the camera 1. Read from the map data. At this time, since the coordinates of the point P0 at the upper left corner of the use area 9 in the map area 10 are (x0, y0), the output image 1 shown in FIG.
The ROM 8 is used by shifting each address of the output image 12 so that the origin O (0, 0) of the second becomes the point P0. R
An image signal corresponding to the top line of the output image 12 is read from the memory 7 in accordance with the movement amount read from the OM 8, sequentially D / A converted by the D / A converter 6, and output to the display 3. Similarly, an image signal corresponding to the second line from the upper end of the output image 12 is read from the memory 7 and output according to the amount of movement of each pixel. In this way, the image signals corresponding to the lower line of the output image 12 are sequentially read from the memory 7 and output.

In this way, the image signals are sequentially taken from the upper line to the lower line of the screen and written into the memory 7, and the image signals corresponding to the respective lines of the output image 12 are converted according to the amount of movement of each pixel. The data is sequentially read from the memory 7 and output to the display 3. When the writing of the image signal of the line at the lower end of the screen is completed, the image signal of the line at the upper end of the screen is fetched cyclically again. Similarly, when the output of the image signal of the line at the lower end of the output image 12 is completed,
Again, an image signal corresponding to the top line of the output image 12 is read from the memory 7 and output in a cyclic manner.

[0013] Here, as shown in FIG.
Is the reference position (center) O2 of the imaging surface 11
In the case where there are deviations Δx and Δy from the camera, the influence of the lens distortion of the camera 1 appears around the lens center O1 of the camera 1, and therefore, as shown in FIG. Is set, it is not possible to correct image distortion due to lens distortion. Therefore, as shown in FIG.
The use area 13 is set at a position deviated by −Δx and −Δy from the center of the area. As a result, the coordinates of the point P1 at the upper left corner of the use area 13 become (x0−Δx, y0−Δy), and the output is performed so that the origin O (0, 0) of the output image 12 becomes this point P1. The ROM 8 is used by shifting each address of the image 12.

Since the output of the output image 12 is performed in order from the origin O, if the address of the point P1 on the ROM 8 corresponding to the origin O is recognized, the output start position is determined. What is necessary is just to read the required movement amount of a pixel in order.

Except for the setting of the use area 13 in the ROM 8, the corrected image signals are sequentially output in the same manner as in the case where the lens center O1 of the camera 1 coincides with the reference position (center) O2 of the imaging surface 11 described above. Output to the display 3. By doing so, even if the lens center O1 of the camera 1 is shifted from the reference position O2 of the imaging surface 11, the image distortion can be corrected using the same ROM 8 without rewriting the ROM 8. It becomes possible.

Note that the deviation of the lens center O1 of the camera 1 from the reference position of the imaging surface 11 can be easily measured. The adjustment of the shift is performed at the time of assembling the camera assembly, that is, at the time of manufacturing. ROM8
The map area 10 inside is set in advance to be wider in consideration of the shift of the lens center O1 of the camera 1 with respect to the reference position of the imaging surface 11, so that each address of the output image is shifted and the ROM 8 is used. This prevents the data in the ROM 8 from being lost.

The image distortion correcting apparatus according to the present invention can be applied not only to the non-interlaced display method generally used in computers and the like, but also to the interlaced display method used in televisions and the like. .

[0018]

As described above, according to the first aspect of the present invention, an image signal of a screen composed of a plurality of lines is sequentially taken in by an imaging camera and written into a memory, and the center of the lens with respect to the reference position of the imaging surface of the imaging camera. By using the map ROM by shifting each address of the output image in accordance with the positional shift amount, the image signal corresponding to each address of the output image is read out from the memory and sequentially output in accordance with the required movement amount of each pixel. As a result, there is no need to write all input signals for one screen to memory as in the past,
It is possible to correct image distortion or the like due to lens distortion in a short time, and to reduce the memory capacity. Even if the lens center of the imaging camera is displaced from the reference position on the imaging surface, the necessary movement amount of each pixel is read from the map ROM without rewriting the map ROM, and the image corresponding to each address of the output image is read. The signal can be read from the memory. Therefore, the image distortion correction device can be easily applied to various cameras having different characteristics.

According to the second aspect of the present invention, the required movement amount of the pixels in the area wider than the output image is stored in the map ROM in advance, so that the displacement amount between the center of the lens and the reference position of the imaging surface is determined. Even if the map ROM is used by shifting each address of the output image, data loss of the map ROM can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image distortion correction device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a map area and a use area of a ROM when a center of a lens of a camera coincides with a reference position of an imaging surface.

FIG. 3 is a diagram illustrating a state in which a lens center of a camera and a reference position of an imaging surface coincide with each other.

FIG. 4 is a diagram showing an output image.

FIG. 5 is a diagram showing a state where the lens center of the camera is shifted from a reference position on an imaging surface.

FIG. 6 is a diagram illustrating a map area and a use area of a ROM when a lens center of a camera is displaced from a reference position on an imaging surface.

[Explanation of symbols]

1 camera, 2 controllers, 3 displays, 4
A / D converter, 5 operation unit, 6 D / A converter, 7 memory, 8 ROM, 9, 13 use area, 10 map area, 11 imaging surface, 12 output image.

Claims (2)

[Claims] 1. An apparatus for capturing an image signal by an imaging camera having a large number of pixels and moving the pixels to correct image distortion caused by lens distortion of the camera, for storing the image signal captured by the imaging camera. A map ROM for storing a required movement amount of a pixel for each address of an output image as a map, and sequentially taking image signals of a screen composed of a plurality of lines by an imaging camera, writing the image signals in the memory, and storing the image signals in the map ROM. An arithmetic unit that reads image signals corresponding to each address of an output image from the memory and sequentially outputs the image signals in accordance with the required movement amount of the pixels, wherein the arithmetic unit includes:
An image distortion correction apparatus, wherein the map ROM is used by shifting each address of an output image according to a positional shift amount of a lens center with respect to a reference position of an imaging surface of an imaging camera. 2. The image distortion correction device according to claim 1, wherein the map ROM stores a required movement amount of pixels in a region wider than an output image in advance.