Imaging systems, program used for controlling image data in same system, method for correcting distortion of captured image in same system, and recording medium storing procedures for same method

• US 20020141636A1
• Filed: 02/08/2002
• Published: 10/03/2002
• Est. Priority Date: 02/09/2001
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kawakami, Kenichi, Kumata, Kiyoshi, Shigeta, Tohru, Wakamoto, Setsunobu, Nakano, Kohichi
• Granted Patent: US 7,058,235 B2
• Time in Patent Office: Days
• US Class Current: 382/154
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G06T 5/006 Geometric correction correction of chromatic aberrations adapted to be used in an image pickup device containing an electronic image sensor H04N23/10; detecting, correcting, reducing or removing artefacts resulting only from the lens unit, e.g. flare, shading, vignetting or "cos4" H04N25/61
• CPC Class Codes: G06T 5/80 Geometric correction
• CPC Class Codes: H04N 23/698 for achieving an enlarged field of view, e.g. panoramic image capture
• CPC Class Codes: H04N 5/2628 Alteration of picture size, shape, position or orientation, e.g. zooming, rotation, rolling, perspective, translation

Abstract

An imaging system of the present invention includes: a reflecting mirror having a geometry of one of two sheets of a two-sheeted hyperboloid; and an imaging section which includes an imaging device for receiving light concentrated by a lens having a center located in any position opposing the reflecting mirror on a rotation axis of the reflecting mirror, wherein the imaging system includes a correction section for performing coordinate transformation on captured image data obtained by capturing an image of a prescribed inspection drawing so as to produce a perspective transformed image data and for correcting distortion in the captured image based on a value regarding a distance between a lens position adapted for the coordinate transformation and a light-receiving surface of the imaging device.

Claims

1. An imaging system, comprising:

a reflecting mirror having a geometry of one of two sheets of a two-sheeted hyperboloid; and

an imaging section which includes an imaging device for receiving light concentrated by a lens having a center located in any position opposing the reflecting mirror on a rotation axis of the reflecting mirror,

wherein the imaging system includes a correction section for performing coordinate transformation on captured image data obtained by capturing an image of a prescribed inspection drawing so as to produce a perspective transformed image data and for correcting distortion in the captured image based on a value regarding a distance between a lens position adapted for the coordinate transformation and a light-receiving surface of the imaging device.

2. An imaging system according to claim 1, wherein the coordinate transformation is performed on the captured image data so as to produce the perspective transformed image data using the following expression:

3. An imaging system according to claim 1, wherein a squared inspection drawing is used as the inspection drawing.

4. An imaging system according to claim 1, wherein the correction section comprises:

an image processing section for transforming the captured image data into the perspective transformed image data so as to produce a perspective transformed image; and

an operation panel for inputting an instruction to increase or decrease the value regarding the distance between the lens position and the light-receiving surface of the imaging device.

5. An imaging system according to claim 1, wherein the correction section comprises:

an image processing section for transforming the captured image data into the perspective transformed image data so as to produce a perspective transformed image; and

an image recognition section for recognizing whether or not the produced perspective transformed image is distorted by comparing the produced perspective transformed image to an image expected to be obtained when the captured image is a central projection image.

6. An imaging system according to claim 4, wherein the image processing section performs coordinate transformation processing according to an instruction signal output by the operation panel.

7. An imaging system according to claim 5, wherein the image processing section performs coordinate transformation processing according to an instruction signal output by the image recognition section.

8. An imaging system according to claim 4, wherein the image processing section comprises:

a CPU connected to a bus line;

an input buffer memory;

a look-up table;

an arithmetic processing circuit; and

an output buffer memory,

wherein;

the CPU controls arithmetic processing;

the input buffer memory stores captured image data;

the look-up table and the arithmetic processing circuit are used for the arithmetic processing; and

the output buffer memory includes the image processing section for storing perspective transformed image data.

9. An imaging system according to claim 5, wherein the image processing section comprises:

a CPU connected to a bus line;

an input buffer memory;

a look-up table;

an arithmetic processing circuit; and

an output buffer memory, wherein;

the CPU controls arithmetic processing;

the input buffer memory stores captured image data;

the look-up table and the arithmetic processing circuit are used for the arithmetic processing; and

the output buffer memory includes the image processing section for storing perspective transformed image data.

10. A program used for controlling image data in an imaging system,

wherein the imaging system comprises:

a computer;

a reflecting mirror having a geometry of one of two sheets of a two-sheeted hyperboloid; and

an imaging section which includes an imaging device for receiving light concentrated by a lens having a center located in any position opposing the reflecting mirror on a rotation axis of the reflecting mirror, and

the program allows the computer to serve as;

a coordinate transformation section for performing coordinate transformation on captured image data obtained by capturing an image of a prescribed inspection drawing so as to produce perspective transformation image data;

a correction section for correcting distortion in the captured image based on a value regarding a distance between a lens position adapted for the coordinate transformation and a light-receiving surface of the imaging device.

11. A method for correcting a captured image in an imaging system, wherein the imaging system comprises:

a reflecting mirror having a geometry of one of two sheets of a two-sheeted hyperboloid; and

an imaging device for receiving light concentrated by a lens having a center located in any position opposing the reflecting mirror on a rotation axis of the reflecting mirror,

the method comprising;

a first step of storing captured image data obtained by capturing an image of a prescribed inspection drawing in an input buffer memory;

a second step of performing coordinate transformation, according to an instruction from a CPU responding to an instruction signal output by an operation panel, on the captured image data stored in the input buffer memory using an arithmetic processing circuit so as to produce perspective transformed image data and storing the perspective transformed image data in an output buffer memory; and

a third step of displaying an image produced from the perspective transformed image data stored in the output buffer memory on a monitor, the image being confirmed by an inspector,

wherein;

when a perspective transformed image obtained by capturing an image of a squared inspection drawing is determined to be distorted at the third step, the inspector inputs to the operation panel an instruction to increase or decrease a value regarding a distance between the lens position and the light-receiving surface of the imaging device such that the operation panel outputs an instruction signal to change the value regarding the distance between the lens position and the light-receiving surface of the imaging device; and

the first through third steps are repeated.

13. An imaging system for transforming captured image data into perspective transformed image data using a value regarding a distance between a light-receiving surface of an imaging device and a lens position used when a perspective transformed image obtained by capturing an image of a prescribed inspection drawing is not determined to be distorted by a method for correcting distortion of a captured image according to claim 11.

14. An imaging system for transforming captured image data into perspective transformed image data using a value regarding a distance between a light-receiving surface of an imaging device and a lens position used when a perspective transformed image obtained by capturing an image of a prescribed inspection drawing is not determined to be distorted by a method for correcting distortion of a captured image according to claim 12.

15. A recording medium storing procedures for a method for correcting distortion of a captured image according to claim 11.

12. A method for correcting a captured image in an imaging system, wherein the imaging system comprises:

a reflecting mirror having a geometry of one of two sheets of a two-sheeted hyperboloid; and

an imaging device for receiving light concentrated by a lens having a center located in any position opposing the reflecting mirror on a rotation axis of the reflecting mirror,

the method comprising;

a first step of storing captured image data obtained by capturing an image of a prescribed inspection drawing in an input buffer memory;

a second step of performing coordinate transformation, according to an instruction from a CPU responding to an instruction signal output by an image recognition section, on the captured image data stored in the input buffer memory using an arithmetic processing circuit so as to produce perspective transformed image data and storing the perspective transformed image data in an output buffer memory; and

a third step for comparing the perspective transformed image data stored in the output buffer memory to expected image data obtained when a captured image is a central projection image by using the image recognition section,

wherein;

when a perspective transformed image obtained by capturing an image of a squared inspection drawing is determined to be distorted at the third step, the image recognition section outputs the instruction signal so as to change the value regarding the distance between the lens position and the light-receiving surface of the imaging device; and

the first through third steps are repeated.

16. A recording medium storing procedures for a method for correcting distortion of a captured image according to claim 12.