JP2003303342A - Method and apparatus for detecting reference position of annular image by omnidirectional imaging - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically set a reference position for determining the development region of an annular image by using a software technology in converting the annular image taken by an omnidirectional imaging lens into a panoramically developed image. <P>SOLUTION: In the method and apparatus for detecting reference positions of the annular image taken by the omnidirectional imaging, the radius of a circular pattern is changed while the center is moved in a prescribed region at the center of the annular image taken by an omnidirectional imaging apparatus. Then, the center of a circle most suitable for the inner circle of the annular image is made to be the center coordinate position of the annular image, and the radius of the circle is the radius of the inner circle of the annular image. Further, the radius of the circular pattern is changed on the outside of the inner circle with the center coordinate position as the center of movement, and the radius of a circle most suitable for the outer circle is made to be the radius of the outer circle. In this way, the coordinate position, and positions of the inner circle and outer circle indicating the development region of the annular image taken by the omnidirectional imaging apparatus into the panoramically developed image are found. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting a reference position required when converting an annular image obtained by omnidirectional photographing using an omnidirectional imaging lens (PAL) into a panoramic image. It is related to.

[0002]

The image photographed by using the omnidirectional image pickup lens becomes a circular image as shown in FIG. This annular image is converted into a panoramic developed image using the MPU as shown in FIG. During this image conversion,
As shown in FIG. 2, if the center coordinate position and the reference position for image conversion consisting of the positions of the inner circle and the outer circle match the annular image, the MPU obtains an appropriate panoramic developed image as shown in FIG. However, if the reference position is in an incompatible state as shown in FIG. 3, the panoramic developed image becomes a curved distorted image as shown in FIG.

Conventionally, in order to eliminate such curvature distortion of the panoramic developed image, the mechanical mounting is adjusted to improve the precision of the mechanical mounting positions of the omnidirectional imaging optical system and the image pickup device, or The annular image was displayed on the display and the reference position of the development area was visually determined.

The object of the present invention has been made in view of the above-mentioned problems, and the adjustment work after the attachment of the image pickup optical system and the image pickup device is absorbed by using the software technique to eliminate the need for mechanical hardware adjustment. An object of the present invention is to provide a method and apparatus for detecting a reference position of an annular image by imaging.

Another object of the present invention is to detect a reference position of an annular image by omnidirectional imaging, which automatically detects and determines a reference position in the annular image when converting the annular image into a panoramic expanded image. And to provide a device.

[0006]

According to the present invention, in a predetermined area at the center of an annular image taken by an omnidirectional image pickup device, the radius of the circular pattern is changed while moving the center coordinates of the circular pattern, and the annular shape is changed. The circle that best fits the inner circle of the image is searched for, the center of the circle is set as the center coordinates of the ring image, and the radius at that time is set as the radius of the inner circle of the ring image. By changing the radius of the circular pattern outside the inner circle and setting the radius of the circle that best fits the outer circle as the radius of the outer circle, the circular image taken by the omnidirectional imaging device is expanded into a panoramic image. Provided is a method and apparatus for detecting a reference position of an annular image by omnidirectional imaging, in which the positions of an inner circle and an outer circle representing a region and the center positions of those circles are obtained.

According to one embodiment of the present invention, the annular image is converted into an image in which the contours representing the inner circle and the outer circle are visualized,
For the inner circle in the revealed image, select the circle that has the best match with the inner circle in the revealed image among the circles whose radii change while moving the center coordinates, and circle the center and radius of the circle. The center coordinates of the inner circle of the image and its radius, and then
By gradually increasing the radius of the circular pattern from the radius of the inner circle centering on its center coordinates and setting the radius of the circle that best matches the outer circle of the revealed image as the radius of the outer circle of the ring image, Provided is a method and apparatus for detecting a reference position of an annular image by omnidirectional imaging, in which a center position of an image, an inner circle radius, and an outer circle radius are obtained to determine a reference position representing a development area on a panoramic image.

[0008]

FIG. 5 is a block diagram showing an overall configuration including a reference position detecting device for an annular image by omnidirectional imaging according to the present invention.

In FIG. 5, the omnidirectional image pickup lens 1 receives light rays from an object in all azimuths around 360 degrees and projects an image of the object on the image pickup element 2. The image sensor 2 converts the subject image into an electric signal and transfers it as digital image data to the MPU 3. The MPU 3 holds the digital image data in the memory as a circular image as shown in FIG. 1 and converts it into a panoramic developed image as shown in FIG. Then, this panoramic image is displayed on the display 4.

When converting the annular image of FIG. 1 into the panoramic developed image of FIG. 2, the reference position consisting of the central coordinate position, the inner circle position and the outer circle position of the annular image added to the figure must be set correctly. is important. This reference position can consist of a center coordinate, an inner circle radius and an outer circle radius.

The present invention obtains the reference position by using the software technique by the MPU 3 of FIG. 5, and its operation flow is shown in FIG. Hereinafter, the present invention will be described in detail with reference to the drawings.

In step 10 of FIG. 6, a noise removal filter is applied to the ring-shaped image as shown in FIG. 1 (the inner circle and the outer circle are not shown). The noise removal filter removes noise from an image having noise such as black and white dots in the image. For example, a median filter can be used. The median filter is, for example, 3 × 3 adjacent 9
The operation of setting the fifth (median value) when the densities of individual pixels are arranged in ascending order as the density value of the central pixel is performed for all pixels. This eliminates density values that are large or small such as noise that jumps out, so that an image from which noise has been removed can be obtained.

Next, the circular image is made to have the edges of the inner circle and the outer circle exposed by using an edge extraction filter. This edge extraction filter consists of horizontal and vertical differential filters. In step 11 of FIG. 6, when the horizontal differential filter having the filter matrix as shown in FIG. 7A is used to filter all pixels, vertical line segments are obtained as shown in FIG. 8A. An image in which is emphasized is formed. Next, in step 12, when filtering processing is performed on all pixels using a vertical differential filter having a filter matrix as shown in FIG. 7B, horizontal line segments are emphasized as shown in FIG. 8B. The formed image is formed. In step 13, by adding these two differential images in the horizontal direction and the vertical direction, it is possible to form a contour image in which the contours of the inner circle and the outer circle of the annular image are emphasized as shown in FIG. 8C. .

In step 14 of FIG. 6, a circle pattern is formed, the radius is changed at each moving point while moving the center point of the circle, and the density of each pixel on the circumference of the circle pattern at each changing point is calculated. The density addition value of each circle is calculated by adding. The density addition value becomes maximum when the circular pattern overlaps with the inner circle of the annular image. In this step, the purpose is to find the center coordinates of the inner circle of the ring image and its radius, so if the height of the image is H, the range of movement of the center point is ± H × 0. The range is 25. Further, the change range of the radius of the circle pattern is set to be larger than H × 0.1 and smaller than H × 0.25. FIG. 9 shows how the center moves and the radius of the circle changes.
The radius of the circle pattern may be gradually changed, and the center position may be moved at each radius change point.
Further, in step 14, the density average value may be obtained instead of the density addition value.

In step 15, the largest density addition value obtained in step 14 is selected, the center of the circle pattern is set as the center coordinates of the annular image, and
Let the radius of the circle be the radius of the inner circle of the annular image.

Then, in step 16, the radius of the circular pattern centered on the center coordinate is gradually changed from the length of the inner circle radius + 1 to the circumference of the circular pattern at the changing point of each radius. The average value of the density values of the pixels along the line is obtained. The radius of the circle pattern may be gradually reduced from the maximum radius, or the added value may be obtained instead of the density value.

In step 17, the average density value at each change point of the radius obtained in step 16 is plotted with a radius R on the horizontal axis and an average density value on the vertical axis to draw a histogram, as shown in FIG. Become. In step 18, the one-dimensional differential filter is applied to the histogram obtained in step 16 to form a histogram in which the edge portion is emphasized as shown in FIG.

The principle of the one-dimensional differentiation in step 18 is shown in FIG.
Will be described in more detail based on. FIG. 12B is a bar graph showing the density average value around a certain edge portion before the one-dimensional differential filter is applied. When this value is indicated by a numerical value, it becomes as shown in the middle column of FIG. The upper column of (a) shows the characteristics of the one-dimensional differential filter (edge extraction filter). This filter characteristic sequence is 1 from the left end to the right.
The result of calculation while moving one by one is as shown in the lower column of the same (a), and when expressed in a graph, it is as shown in the same (c).
In FIG. 12, it is considered that the distribution in the contour portion of the contour image is as shown in (b) before applying the filter. Here, the 11th position has the highest density average value. When a one-dimensional differential filter is applied to this, the same (c)
It becomes the maximum at the position of 4, as shown in. Originally, it is preferable to set the radius of the outer circle of the contour image at the edge portion of the contour portion, and therefore it is preferable that a peak appears at the edge portion as shown in FIG.

Therefore, in step 19 of FIG. 6, a circle having a radius 4 having the highest density average value in the differential histogram is selected, and the radius of the circle is determined as the radius of the outer circle of the annular image.

As described above, it is possible to calculate the reference position of the annular image, which is composed of the center coordinate position of the annular image, the radius of the inner circle and the radius of the outer circle.

If the image data of only the area designated by the reference position of the ring-shaped image determined as described above, that is, the expansion area of the ring-shaped image into the panoramic image is transferred to another device, The transfer rate of the ring image can be improved.

[0022]

According to the present invention, since the center coordinate position of the annular image, the radius of the inner circle and the radius of the outer circle can be automatically calculated and obtained using software technology, mechanical adjustment is not required. Not only is it unnecessary, but the operation of visually determining the development area of the annular image is also unnecessary.

[Brief description of drawings]

FIG. 1 is a diagram showing a normal development area of an annular image captured by an omnidirectional imaging lens.

FIG. 2 is a diagram showing a panoramic developed image obtained by converting the annular image of FIG. 1 into a rectangle.

FIG. 3 is a diagram showing a ring-shaped image showing a state in which an inappropriate expansion area is designated.

FIG. 4 is a diagram showing a panoramic developed image obtained as a result of designating an unsuitable developed area as in FIG.

FIG. 5 is a block diagram showing a schematic configuration of the present invention.

FIG. 6 is a flowchart showing a procedure for implementing the present invention.

FIG. 7 is a diagram showing a filter matrix of a differential filter for obtaining a contour image.

FIG. 8 is a diagram illustrating a process of obtaining a contour image when differential filters are applied in the vertical direction and the horizontal direction.

FIG. 9 is a diagram for explaining an operation for obtaining the center coordinates of the contour image and the radius of the inner circle.

FIG. 10 is a histogram used for obtaining the outer circle radius of the contour image.

11 is a histogram after applying the histogram of FIG. 10 to a one-dimensional differential filter.

FIG. 12 is a diagram for explaining the principle of applying a one-dimensional differential filter to a histogram to obtain an outer circle of a contour image.

[Explanation of symbols]

1 Omnidirectional imaging lens 2 image sensor 3 MPU 4 display

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G06T 7/60 250 G06T 7/60 250A H04N 5/225 H04N 5/225 Z 7/18 7/18 K ( 72) Inventor Barrage Verg Borghi 1111, Budapest Zenta You. 1. , Hungary F-term (reference) 2H059 BA11 5B057 AA20 BA02 CA02 CA08 CA12 CA16 CB02 CB08 CB12 CB16 CC01 CD12 CE02 CE03 CE06 DA07 DB02 DB05 DB09 DC06 DC16 DC23 5C022 AB68 AC54 5C054 FA02 FA04L0696 FA02 FA04L0696 FA02

Claims (14)

[Claims] 1. A method for detecting a reference position of an annular image by omnidirectional imaging, wherein an annular image is captured by an omnidirectional imaging device and processed into a contour image in which contours of an inner circle and an outer circle of the annular image are clarified. Then, a circle that best fits the contour of the contour image is selected based on a circle whose center and radius change, and the center image of the selected circle and its radius are used to make the annular image a panoramic image. The method for obtaining a reference position for designating a development area of the ring-shaped image when the development is carried out to. 2. The method according to claim 1, wherein the reference positions are a center coordinate position, an inner circle position and an outer circle position of the annular image. 3. The method according to claim 1, wherein the reference position is a center coordinate position of the annular image, a radius of the inner circle from the center coordinates, and a radius of the outer circle from the center coordinates. The method. 4. The method according to claim 1, wherein the image processing step applies an edge extraction filter to the annular image. 5. The method according to claim 1, wherein in the image processing step, a noise removal filter is applied to the annular image and then an edge extraction filter is applied. 6. The method according to claim 4, wherein the step of applying the edge extraction filter applies a horizontal differential filter and a vertical differential filter to the annular image to form respective differential images, The above method, wherein the differential images are summed to obtain the contour image. 7. The method according to claim 1, wherein in the step of selecting the circle, the circle is moved at each change point of the circle whose radius changes while moving the center in a predetermined area in the center of the annular image. The method, wherein an added value or an average value of the density values of the above pixels is obtained, and a circle having the maximum value among the added values or the average values is selected. 8. The method according to claim 7, wherein in the step of obtaining the reference position, the center coordinates of the selected circle are set as the center coordinates of the annular image, and the radius of the circle is the inner circle of the annular image. The radius of the circle, further changing the radius of the circle centered on the center coordinates to find the circle that best fits the outer circle, and set the radius of the circle as the radius of the outer circle of the annular image,
The method. 9. The method according to claim 1, wherein in the step of selecting the circle, the circle is moved at each change point of the circle whose center is moved and the radius is changed in a predetermined area of the center of the annular image. The first step of obtaining an added value or an average value of the density values of the above pixels and selecting a circle having the maximum value among the added values or the average value, and centering the center coordinates of the selected circle As the radius is larger than the radius of the inner circle, the addition value or average value of the density values of the pixels on the circle is calculated at each change point of the circle, and the maximum value of these addition values or average values is calculated. A second step of selecting the indicated circles. 10. The method according to claim 9, wherein the step of obtaining the reference position uses the center coordinates of the circle selected in the first step as the center coordinates of the annular image,
The method, wherein the radius of the circle is the radius of the inner circle of the annular image, and the radius of the circle selected in the second step is the radius of the outer circle of the annular image. 11. The method according to claim 9, wherein the second step is an area in which the radius is larger than the radius of the selected circle with the center coordinates of the circle selected in the first step as the center. A histogram is formed with respect to the added value or the average value of the density values of the pixels on the circle that change in, the differential filter is applied to the histogram to form a differential histogram, and the radius of the circle corresponding to the maximum point of the differential histogram is defined as The method, wherein the radius is the outer circle of the annular image. 12. A reference position detecting device for an annular image by omnidirectional imaging, comprising: an omnidirectional imaging device for capturing an annular image and a contour image in which contours of an inner circle and an outer circle of the annular image are clarified. Means for selecting a circle that best fits the contour of the contour image based on a circle whose center and radius change, and using the center coordinates and radius of the selected circle, the annular image And a means for obtaining a reference position for designating a development area of the annular image when the image is developed into a panoramic image. 13. The apparatus according to claim 12, wherein the processing means is an edge extraction filter that reveals the inner circle and the outer circle of the contour image. 14. The apparatus according to claim 13, wherein the edge extraction filter includes a horizontal differential filter that makes vertical line segments visible, and a vertical differential filter that makes horizontal line segments visible. And means for obtaining the contour image by summing the annular images obtained by the filters.