JP2013205295A - Image processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing device that can reproduce a three-dimensional shape with high accuracy by obtaining a lot of pieces of information from a pattern image to be projected on a three-dimensional object.SOLUTION: Since three light sources LD1 to LD3 have an optical axis physically deviated, a pattern image to be formed by each of light beams becomes a pattern image separated from each other at an imaging position. A pattern image to be formed by use of a green light beam and a pattern image to be formed by use of a red light beam are arranged at an equal interval between pattern images to be formed by use of a blue light beam. Thus, if a camera 14 uses an imaging element capable of discriminating a blue, a green and a red, three pattern images can be read at the same time without using a lens of a high resolution. In this way, when compared with emission of a single light beam, three-time information amount can be obtained, and thereby a shape of an object 18 can be reproduced with high accuracy.

Description

  The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus that can project a pattern image onto an object and restore a three-dimensional shape. The image processing apparatus of the present invention can be used in various fields such as the medical field, clothing field, and security field.

  For example, in order to measure a face or the like, high-speed measurement, acquisition of a high-density point group, accuracy, and the like are important. For this reason, recently, an active three-dimensional measurement technique, in particular, an approach of acquiring a shape in a short time by speeding up a pattern coding method has been actively studied (see Patent Document 1). For example, acquiring 3D data of a human face

JP 2009-3000277 A

  In the pattern coding method, a three-dimensional shape is formed by projecting a pattern image onto an object with a projector and photographing it. For this reason, a correspondence relationship between the feature points of the projection pattern image and the posture of the photographed object is necessary. Many pattern coding schemes do this by temporally coding projector pixel position information into multiple patterns.

  By the way, as a pattern image projected onto a three-dimensional object, there is a striped pattern (slit image) formed by passing through a plurality of slits formed at a predetermined pitch. However, in order to accurately reproduce the shape of an object, the pattern image projected onto the object may be made sharper (thin lines) to obtain higher-density information. When the image is projected onto a three-dimensional shape with projections and depressions, high-density information may not be obtained due to blurring of the pattern image. In addition, in order to capture a sharp pattern image, a high-resolution optical system and an image sensor are required, which increases the cost.

  The present invention has been made in view of the above-described problems, and an image processing apparatus capable of obtaining a large amount of information from a pattern image projected onto an object and reproducing a three-dimensional shape with high accuracy without increasing costs. The purpose is to provide.

The image processing apparatus according to claim 1, wherein the image processing apparatus obtains the shape of the object by reading a pattern image irradiated on the object.
A plurality of point light sources each having a different wavelength;
A first lens that converts or condenses a plurality of light beams output from the point light source into substantially parallel light;
An image forming lens for forming a pattern image formed according to the light beam that has passed through the first lens on the object;
The pattern image formed on the object according to light beams having different wavelengths can be distinguished and read.

  The present invention forms pattern images at different positions on the object by utilizing the fact that the optical axis is physically shifted between a plurality of different point light sources. However, when the pattern images formed by shifting are the same color, the image pickup means for reading the pattern image requires a high resolution, resulting in an increase in cost. On the other hand, according to the present invention, the pattern image formed on the object in accordance with the light beams having different wavelengths can be distinguished and read. Compared with the case where only the formed image is photographed, the amount of information proportional to the number of light sources can be obtained, whereby the three-dimensional shape can be reproduced with higher accuracy. The light having the wavelengths of the plurality of light sources may be visible light or infrared light as long as the wavelengths are different from each other. “Differentially read” refers to data obtained by converting a pattern image formed by light rays output from one of the plurality of light sources, and a light source different from the previous period among the plurality of light sources. This means that the data obtained by converting the pattern image formed by the output light beam can be identified.

  The pattern image is preferably formed by the pattern image forming means based on the light rays emitted from the plurality of point light sources. In such a case, the “pattern forming means” is a means for giving a predetermined pattern to the beam profile after light transmission, and an element such as a slit or a grating that forms a pattern by combining the light transmission blocking area and the light transmission area, A pattern forming element using a condensing element such as a microlens array is also applicable. Furthermore, a pattern image forming means in which the light source itself has a pattern structure also corresponds.

  A point light source is a light source whose output beam size is small compared to the focal length f of the first lens that converts or condenses light output from the point light source into substantially parallel light. Point to. Examples include laser diodes, LEDs, and light sources output from optical fibers.

  The lens that converts or condenses the light beam output from the point light source into substantially parallel light includes a single lens or a double lens including a plurality of lenses.

  Parallel light refers to a light beam collimated by a light beam output from one of the plurality of light sources.

  An image processing apparatus according to a second aspect is the invention according to the first aspect, wherein the plurality of point light sources are arranged such that irradiation points are arranged in substantially the same plane.

  By arranging a plurality of point light sources on substantially the same plane, it is possible to irradiate a pattern image on the previous three-dimensional object in substantially the same focus state. However, a slight deviation from the same plane arrangement by performing an optimization considering the effect of wavelength dependency of the optical element such as a lens used here is within an allowable range.

  According to a third aspect of the present invention, in the invention of the first or second aspect, the plurality of point light sources are three light sources having wavelengths of three colors of red, green, and blue, respectively. Features.

  Since commercially available image sensors can generally distinguish blue, red, and green, an image processing apparatus can be formed at low cost using a general-purpose image sensor by setting a plurality of wavelengths to these bands.

  According to the present invention, it is possible to provide an image processing apparatus capable of obtaining a large amount of information from a pattern image projected onto a three-dimensional object and reproducing a three-dimensional shape with high accuracy without increasing costs.

(A) is a figure which shows an example of a structure of the image processing apparatus 10, (b) is a figure which shows the structure of the image processing means 16. FIG. 2 is a diagram illustrating a schematic configuration of a projector 12. It is a figure which shows the example of a pattern image.

  Hereinafter, an image processing apparatus according to an embodiment of the present invention will be described. With reference to FIG. 1, the structure of the image processing apparatus 10 which concerns on embodiment of this invention is demonstrated. FIG. 1A is a diagram illustrating an example of the configuration of the image processing apparatus 10, and FIG. 1B is a diagram illustrating the configuration of the image processing unit 16.

  Referring to FIG. 1A, an image processing apparatus 10 is mainly composed of a projector 12 as a projecting unit, a camera 14 as a photographing unit, and an image processing unit 16 composed of, for example, a personal computer. Yes.

  FIG. 2 is a diagram showing a schematic configuration of the projector 12. The projector 12 has a function of projecting a pattern image onto an object 18 that is a three-dimensional object, and includes a first light source LD 1 that emits a blue light beam, a second light source LD 2 that emits a green light beam, and a red light source LD 2. It has a third light source LD3 that emits a light beam, a collimating lens COL, a slit plate SL that is a pattern image forming means, and an imaging lens LS. Here, the light sources LD1 to LD3 have the emission points arranged at equal intervals on the same line and have the optical axes parallel to each other. However, for example, the emission points may be provided on the apex of a regular triangle.

  The blue light beam radiated and radiated from the first light source LD1 is converted into parallel light by the collimator lens COL, and is passed through the slit plate SL having a plurality of pillars, thereby giving a striped pattern image, and an imaging lens. By LS, an image of the specific column part PLx is formed on the point P1 of the object 18 as a line image. The green light beam radiated and radiated from the second light source LD2 is converted into parallel light by the collimator lens COL, and is passed through the slit plate SL to give a striped pattern image. By the imaging lens LS, the same column portion is provided. The PLx image is formed as a line image at a point P2 different from the point P1 of the object 18. The red light diverging and radiated from the third light source LD3 is converted into parallel light by the collimator lens COL, and is given a striped pattern image by passing through the slit plate SL. The same column portion is formed by the imaging lens LS. The PLx image is formed as a line image at a point P3 different from the points P1 and P2 of the object 18.

  FIG. 3A is an example of a pattern image formed using, for example, blue light emitted from the first light source LD1. Here, the line-to-line distance of the pattern image is Δ. FIG. 3B is an example of a pattern image formed by using light rays diverged and emitted from three light sources LD1 to LD3. Here, for easy understanding, a pattern image formed using green light is indicated by a dotted line, and a pattern image formed using red light is indicated by a one-dot chain line.

  As described above, since the optical axes of the three light sources LD1 to LD3 are physically shifted, the pattern images formed by the light beams emitted from the light sources LD1 to LD3 are adjusted by adjusting the objective distance of the object 18, respectively. Irradiation can be performed with a deviation (PLx in FIG. 3). By adjusting the distance from the imaging lens LS to the object 18, the amount of mutual shift can be set to (Δ / 3). Therefore, the pattern image formed using the blue light beam is formed using the green light beam. The pattern image to be formed and the pattern image formed using the red light beam are arranged at equal intervals. Further, since a point light source is used, pattern irradiation to the object 18 can be performed without causing significant blur even if the point light source deviates from the position of the optimum focus (objective distance). Therefore, if the camera 14 uses an image sensor that can distinguish blue, green, and red, three pattern images can be read simultaneously without using a high-resolution lens. Compared with the case where a single light beam shown in FIG. 5 is emitted, it is possible to obtain three times the amount of information, so that the shape of the object 18 can be reproduced with high accuracy.

  A lattice plate or a microlens array may be used instead of the slit SL. The effects of the present invention can be obtained even if light sources having different two wavelengths are used.

  The camera 14 is means for photographing light reflected from an object by projecting light with the projector 12, and for example, a solid-state imaging device such as a CCD image sensor having a color filter made of blue, green, and red is a candidate. Although it is mentioned, if it is a camera provided with the filter which isolate | separates and cuts off the wavelength of interest, it can be a candidate. A two-dimensional image is taken by the camera 14, and data based on the two-dimensional image is subjected to image processing by the image processing means 16, whereby the three-dimensional shape of the object 18 is restored. Here, it is assumed that the relative positional relationship between the camera 14 and the projector 12 is known, for example, by calibrating in advance, calibrating online, or self-calibrating.

  With reference to FIG. 1B, the configuration of the image processing means 16 for restoring a three-dimensional shape from a two-dimensional image will be described.

  The image processing means 16 of the present embodiment mainly includes an image processing unit 30, a control unit 20, an input unit 22, a storage unit 24, a display unit 26, and an operation unit 28. The overall schematic function of the image processing means 16 is to perform image processing on the input two-dimensional image, restore the three-dimensional shape, and output it. Further, the embodied image processing means 16 may be a computer such as a personal computer in which an application (program) for executing a predetermined function is installed, or dedicated to image processing configured to execute the predetermined function. It may be configured as a device. Furthermore, the parts constituting the image processing means 16 are electrically connected to each other via a bus.

  The image processing unit 30 is a part that performs a main image processing function, and includes an intersection acquisition unit 32, a first solution calculation unit 34, a second solution calculation unit 36, and a three-dimensional shape restoration unit 38.

  The intersection acquisition unit 32 (first calculation unit) is a part that acquires an intersection between a pattern in which a vertical pattern is observed and a pattern in which a horizontal pattern is detected from a two-dimensional image captured by the camera 14.

  The first solution calculation unit 34 (second calculation unit) is configured such that a constraint condition in which the two patterns share an intersection, a constraint condition in which a plane including the pattern passes a predetermined line, a position between the camera 14 and the projector 12. This is a part for calculating the first solution including the degree of freedom based on the conditions obtained from the relationship.

  The second solution calculation unit 36 (third calculation unit) is a part that calculates the second solution by eliminating the degree of freedom of the first solution calculated by the first calculation unit.

  The three-dimensional shape restoration unit 38 is a part that restores the three-dimensional shape of the photographed object based on the calculated second solution.

  The control unit 20 is a part that controls the operation of the entire image processing means 16 (the image processing unit 30, the input unit 22, the storage unit 24, and the display unit 26).

  The input unit 22 is a part where information is input to the image processing unit 16 from the outside. In the present embodiment, a moving image or a still image that is a two-dimensional image is input.

  The storage unit 24 is a fixed storage disk represented by an HDD (Hard Disk Drive), a removable storage disk such as a CD (Compact Disc) or a DVD (Digital Versatile Disk), a fixed or removable semiconductor memory, or the like. is there. In the present embodiment, the storage unit 24 stores a two-dimensional image before processing and a three-dimensional shape restored from the two-dimensional image.

  Further, the storage unit 24 stores a program for executing the following image processing method. This program is called by the user operating the operation unit 28, and executes the functions of the respective parts described above. Specifically, the program operates each part so as to restore three-dimensional shape data from the input two-dimensional image data.

  The display unit 26 is, for example, a liquid crystal display, a CRT (Cathode Ray Tube), or a video projector, and displays an input two-dimensional image and a three-dimensional shape restored based on the two-dimensional image.

  The operation unit 28 is, for example, a keyboard or a mouse. When the user operates the operation unit 28, the image processing unit 16 restores a three-dimensional shape from the two-dimensional image. Note that a mathematical method for restoring a three-dimensional shape from a two-dimensional image is omitted because it is described in Japanese Patent Application Laid-Open No. 2009-300277.

  According to the present invention, it is possible to obtain a large amount of information by using a pattern image formed by three color light beams that have passed through the slit plate SL in one shooting with the camera 14, thereby further increasing the three-dimensional shape. Can be reproduced with accuracy.

DESCRIPTION OF SYMBOLS 10 Image processing apparatus 12 Projector 14 Camera 16 Image processing means 18 Object 20 Control part 22 Input part 24 Storage part 26 Display part 28 Operation part 30 Image processing part 32 Intersection acquisition part 34 1st solution calculation part 36 2nd solution calculation part 38 Three-dimensional shape restoration unit COL Collimating lens LD1 First light source LD2 Second light source LD3 Third light source LS Imaging lens SL Slit plate

Claims (3)

In an image processing apparatus that obtains the shape of the object by reading a pattern image irradiated on the object,
A plurality of point light sources each having a different wavelength;
A first lens that converts or condenses a plurality of light beams output from the point light source into substantially parallel light;
An image forming lens for forming a pattern image formed according to the light beam that has passed through the first lens on the object;
An image processing apparatus, wherein a pattern image formed on the object according to light beams having different wavelengths can be distinguished and read.   The image processing apparatus according to claim 1, wherein the plurality of point light sources have irradiation points arranged in substantially the same plane.   The image processing apparatus according to claim 1, wherein the plurality of point light sources are three light sources having wavelengths of three colors of red, green, and blue, respectively.