WO2014002000A1

WO2014002000A1 - Image acquisition apparatus and process

Info

Publication number: WO2014002000A1
Application number: PCT/IB2013/055191
Authority: WO
Inventors: Tak Wai Lau; Wing Hong Lam
Original assignee: Tak Wai Lau; Wing Hong Lam
Priority date: 2012-06-25
Filing date: 2013-06-25
Publication date: 2014-01-03

Abstract

An image acquisition process, for example an image acquisition process for operating an image acquisition apparatus to acquire an image of a target object having an alignment reference device. The image acquisition apparatus comprises a processor and an image capturing device. The process comprises devising a visual alignment guide which is for cooperative alignment with an alignment reference device on said target object, devising feedback guidance comprising a set of feedback guidance instructions to guide a user to aim the image acquisition apparatus at the target object so that the visual alignment guide and the alignment reference device will move towards said cooperative alignment upon following said set of feedback guidance instructions, and informing a user that the image of the target object is ready to be captured when the visual alignment guide and the alignment reference device are at said cooperative alignment.

Description

IMAGE ACQUISITION APPARATUS AND PROCESS

FIELD

[001] The present disclosure relates to image acquisition, for example, image acquisition by mobile image capturing apparatus. More particularly, the present disclosure relates to image capturing by mobile image capturing apparatus for authentication or other applications.

BACKGROUND

[002] Counterfeiting is a serious problem that not only disrupts normal commercial or noncommercial activities but also poses health, safety as well as security problems. Many types of anti-counterfeiting measures have been devised to help fight counterfeiting. For example, genuine goods carry authentication tags or codes as an example of authentication devices to facilitate verification of authenticity of goods or products. However, even authentication devices have become the subject of rampant counterfeiting. As a result, authentication devices of ever increasing sophistication and enhanced anti-counterfeiting features are being developed from time to time to combat counterfeiting. [003] The more sophisticated authentication devices usually include embedded security devices that are coded with highly precise security features. Digitally coded watermarks and moire patterns containing phase modulation coded security features are example of such security devices that are known to be useful. The high precision nature of such authentication devices would mean that a highly accurate and precise image of the authentication device is often required in order to facilitate verification of authenticity in many authentication applications.

[004] Therefore, it would be advantageous if enhanced image acquisition methods and apparatus are provided to facilitate obtaining images of authentication devices suitable to facilitate verification as and when needed.

[005] As mobile apparatus with built-in data processors such as mobile phones, smart phones, and mobile computing apparatus such as notebook and tablet computers are increasingly equipped with high quality image capture devices, it would be advantageous if such mobile apparatus are operable as image acquisition apparatus suitable to acquire image to facilitate verification, or even as authentication apparatus with built-in image acquisition and authenticity verification capability.

DESCRIPTION OF FIGURES

[006] Example of methods and apparatus suitable to obtain images of authentication devices to facilitate verification of authenticity are described herein by way of example with reference to the accompanying Figures, in which:-

Figure 1 is a functional block diagram of an example image acquisition apparatus of the present disclosure,

Figure 1 A depicts an example alignment reference device, Figure 1 B depicts an example visual alignment guide,

Figure 1 C depicts an example alignment reference device,

Figure 1 D depicts an example visual alignment guide,

Figure 2 shows an example image acquisition apparatus according to the present disclosure, Figure 3 shows a user holding the example image acquisition apparatus of Figure 2,

Figure 3A is a schematic side view depicting the example image acquisition apparatus and the target object in an operation mode of Figure 3,

Figures 3B is a schematic perspective view depicting the example image acquisition apparatus and the target object when in the operational mode of Figure 3, Figure 4 shows the example image acquisition apparatus of Figure 2 in which an image of a target object is aligned and ready to be captured,

Figures 4A to 4G depict various graphical feedback signals, and

Figure 5 depicts an interim image of an alignment reference device of the target while undergoing an alignment process with a visual alignment guide on the display of the image acquisition apparatus of Figure 2. DESCRIPTION

[007] There is disclosed an image acquisition process, for example an image acquisition process for operating an image acquisition apparatus to acquire an image of a target object having an alignment reference device. The image acquisition apparatus comprises a processor and an image capturing device. The process comprises devising a visual alignment guide which is for cooperative alignment with an alignment reference device on said target object; devising feedback guidance that includes a set of feedback guidance instructions to guide a user to aim the image acquisition apparatus at the target object, so that the visual alignment guide and the alignment reference device will move towards said cooperative alignment upon following said set of feedback guidance instructions; and informing a user that the image of the target object is ready to be captured when the visual alignment guide and the alignment reference device are at said cooperative alignment. The feedback guidance may be in a visual and/or audio form.

[008] Devising feedback guidance to guide a user to move an image acquisition apparatus towards cooperative alignment corresponding to a position of proper alignment is advantageous as it facilitates capturing of an image of sufficient fidelity to perform high precision applications such as authentication or identification verifications.

[009] For example, the process may comprise devising a set of feedback guidance instructions to correspond to a set of predetermined alignment criteria, and the set of predetermined alignment criteria is to facilitate capturing of an image of the target object by the image capturing device which satisfies a prescribed quality of fidelity.

[0010] The process may include devising a graphical alignment device on the visual alignment guide, and the graphical alignment device is to cooperate with a graphical reference device on the alignment reference device on the target object to collectively form a varying graphical feedback signal, for example, on approaching said cooperative alignment.

[001 1 ] The process may include devising a graphical alignment device and a graphical reference device on the visual alignment guide, and the graphical alignment device is to cooperate with the graphical reference device to collectively form a varying graphical feedback signal, for example, on approaching said cooperative alignment. [0012] In an example, the graphical alignment device and the graphical reference device are graphically complementary, and the graphical feedback signal comprises a visual guidance sign which is an instantaneous combinatorial product of the graphical alignment device and the graphical reference device, whereby instantaneous guidance information is provided to a user. [0013] To make the process more accessible, the process is in the form of application software for installing onto a computing device, for example a mobile computing device such as a smart phone or tablet computer having a built-in image capturing device and display, so that the public can use their mobile computing devices as authentication apparatus upon installation and execution of the process. [0014] Therefore, there is also disclosed an image acquisition apparatus comprising a processor, an image capturing device and a visual alignment guide; wherein the visual alignment guide is for alignment with an alignment reference device on a target object, and the processor is to provide feedback guidance to a user upon processing of an interim or instantaneous image of the target object while the apparatus is aiming at the target object such that the image of the target object is ready to be acquired by the image capturing device, and wherein the feedback guidance is to guide the user to aim the image acquisition apparatus at the target object such that alignment between the visual alignment guide and alignment reference device on the target object satisfies a set of predetermined alignment criteria.

[0015] In an example, the processor is set to generate feedback guidance to inform a user that an image of the target is ready to be captured when the alignment between the visual alignment guide and alignment reference device on the target object satisfies the set of predetermined alignment criteria, and the set of predetermined alignment criteria is to facilitate capturing of an image of the target object by the image capturing device which satisfies a prescribed quality of fidelity. [0016] The above and other advantageous aspect of the present disclosure will be further described below by way of non-limiting embodiments.

[0017] An example image acquisition apparatus 100 depicted in the functional block diagram of Figure 1 comprises a processor 102, an antenna 104, a memory 106, a display 108, an image capturing device 110, a light emitting device 112, and a 3-axis accelerometer 114. When the image acquisition apparatus 100 operates to capture an image of a target object, the processor 102 will execute a pre-defined image acquisition process comprising a set of instructions which is designed for that target object. In general, a target object to be captured for the object of the present applications will usually comprise a characteristic alignment reference device. Therefore, the image acquisition process will devise a compatible visual alignment guide to facilitate capturing of an image of the object to meet requirements of fidelity for the applications. The image acquisition process will also devise a user interactive input to operate the image capturing device to capture an image of the target object when a prescribed set of alignment criteria corresponding to satisfying the requirements of fidelity is met.

[0018] An example characteristic alignment reference device 120 depicted in Figure 1 A comprises four peripheral alignment reference elements 122 which are distributed on four corners of a square inside and a central alignment reference element 124 at the center of the square. Each peripheral alignment reference element 122 comprises a grey square frame on the outside, a solid grey square inside and co-centered with the outer grey square frame, and a light or empty square frame between the solid square and the outer square frame. The central alignment reference element 124 comprises a dark circular dot. The four peripheral alignment reference elements 122 and the central alignment reference element 124 collectively form a graphical reference device.

[0019] An example visual alignment guide 140 depicted in Figure 1 B comprises an alignment guide frame, four peripheral alignment guide elements 142 which are distributed within the alignment frame, and a central alignment guide element 144 at the center of the square. The alignment frame comprises four L-shaped brackets 146 which are distributed at the four corners of a square and which collectively defines the boundary of a square-shaped alignment window. The four peripheral alignment guide elements 142 are distributed on four corners of a square inside and co-centered with the alignment frame. Each peripheral alignment guide element 142 comprises a grey square frame on the outside, a solid grey square inside and co-centered with the outer grey square frame, and a light or empty square frame between the solid square and the outer square frame. The central alignment guide element 144 comprises a dark circular ring enclosing a light circular center. The four peripheral alignment guide elements 142 and the central alignment guide element 144 collectively form a graphical alignment device.

[0020] The alignment reference device 120 and the visual alignment guide 140 are adapted to be graphically complementary when in a cooperative alignment relationship. For example, the peripheral alignment reference elements 122 and the corresponding peripheral alignment guide elements 142 will squarely overlap, and the solid circular dot of the central alignment reference element 124 will sit squarely inside the circular ring of the central alignment guide element 144.

[0021 ] The example image acquisition apparatus 100 depicted in Figure 2 is a smart phone running an image acquisition process as disclosed herein which is downloaded as an application software ("APP") and installed on the smart phone.

[0022] In use, a user will hold the image acquisition apparatus 100 and aim the image capturing device 110 at the target device as depicted in Figures 3, 3A and 3B until an interim or instantaneous image of the alignment reference device 120 on the target object appearing on the display is inside the alignment guide frame of the visual alignment guide 140. For example, a user will hold the apparatus at 8-10 cm vertically above the target object in order to capture an image of the target object with sufficient image data for processing. It will be noted that the graphical reference device and the graphical alignment device collectively define a visual guidance sign to provide feedback guidance to a user.

[0023] For example, when the graphical reference device and the graphical alignment device are in cooperative alignment as depicted in Figure 4, the two devices are graphically complementary and the image satisfies the alignment criteria and is acceptable for capturing. Upon sighting such a cooperative alignment relationship. A user will activate the apparatus to capture an image of the target object. It will be noted that when the two devices are in cooperative alignment, the four inner squares of the four peripheral alignment reference elements 122 squarely overlap with the four inner squares of the four peripheral alignment guide element 142, and the dark circular dot of the central alignment reference element 124 overlaps squarely with the light circular center of the central alignment guide element 144. When cooperative alignment occurs, an optional message such as Object in Position for Image Capturing" can be shown as textual feedback guidance. [0024] In the examples shown in Figure 4A to 4F, the four peripheral alignment reference elements 122 are not expressly shown for better clarity and simplicity.

[0025] When the visual feedback guidance sign which is formed by instantaneous combination of the graphical reference device and the graphical alignment device is as depicted in Figure 4A such that circular dot of the central alignment reference element 124 is on the left of the light circular center of the central alignment guide element 144, the apparatus is tilted too much to the left. This sign informs the user to tilt the apparatus towards the right in order to move into the cooperative alignment. This corresponds to rotating the apparatus 100 opposite to the arrowed direction about its longitudinal axis -X,+X as depicted in Figure 3B. An optional message such as "tilt right" can be shown as textual feedback guidance.

[0026] When the visual feedback guidance sign is as depicted in Figure 4B such that circular dot of the central alignment reference element 124 is on the right of the light circular center of the central alignment guide element 144, the apparatus is tilted too much to the right. This sign informs the user to tilt the apparatus towards the left in order to move into the cooperative alignment. This corresponds to rotating the apparatus 100 in the arrowed direction about its longitudinal axis -X,+X as depicted in Figure 3B. An optional message such as "tilt left" can be shown as textual feedback guidance.

[0027] When the visual feedback guidance sign is as depicted in Figure 4C such that circular dot of the central alignment reference element 124 is on the lower side of the light circular center of the central alignment guide element 144, the apparatus is tilted too much downwards about its middle traverse axis. This sign informs the user to tilt the apparatus upwards in order to move into the cooperative alignment. This corresponds to rotating the apparatus 100 opposite to the arrowed direction about its transverse middle axis -Y,+Y as depicted in Figure 3B. An optional message such as "tilt up" can be shown as textual feedback guidance.

[0028] When the visual feedback guidance sign is as depicted in Figure 4D such that circular dot of the central alignment reference element 124 is on the upper side of the light circular center of the central alignment guide element 144, the apparatus is tilted too much upwards about its middle traverse axis. This sign informs the user to tilt the apparatus downward in order to move into the cooperative alignment. This corresponds to rotating the apparatus 100 in the arrowed direction about its transverse middle axis -Y,+Y as depicted in Figure 3B. An optional message such as "tilt down" can be shown as textual feedback guidance. [0029] When the visual feedback guidance sign is as depicted in Figure 4E such that circular dot of the central alignment reference element 124 is smaller than the light circular center of the central alignment guide element 144, the apparatus is too far away. This sign informs the user to move the apparatus closer towards the target object in order to move into the cooperative alignment. This corresponds to moving the apparatus 100 in the +Z direction as depicted in Figure 3B. An optional message such as "move closer" can be shown as textual feedback guidance. [0030] When the visual feedback guidance sign is as depicted in Figure 4F such that circular dot of the central alignment reference element 124 is bigger than the light circular center of the central alignment guide element 144, the apparatus is too close. This sign informs the user to move the apparatus away in order to move into the cooperative alignment. This corresponds to moving the apparatus 100 in the -Z direction as depicted in Figure 3B. An optional message such as "move away" can be shown as textual feedback guidance.

[0031 ] As depicted in Figure 4G, there is also provided a visual guide sign to indicate the level of stability of the apparatus. Signals indicating stability of the apparatus, such as the values of the stability meter shown, are generated by the built-in 3-axis accelerometer and processed by the processor for display. A user will need to hold the apparatus in a more steady way if the stability level is low in order to capture an image of a sufficient level of fidelity. When the apparatus is unstable, an optional message such as "hold steady" can be shown as textual feedback guidance. The 3-axis accelerometer is optional as the level of stability can be determined by the processor measuring the movement of the interim image in a given time window.

[0032] Figures 1 C and 1 D depict another example alignment reference device 220 and a corresponding visual alignment guide 240, in which the alignment reference device 220 on the target object does not have a central alignment reference element but the visual alignment guide 240 on the display of the apparatus has a corresponding central alignment guide element 244. In this example, the apparatus is to generate a central alignment element according to the interim image, and the central alignment element to be generated from the interim image is a graphical sign which is equivalent, if not identical, to the central alignment reference element 124 and for equivalent purposes to assist alignment. The central alignment guide element 244 may be generated at the center of the interim image using the interim image. For example, the processor may generate the central alignment guide element 244 by determining the position of the center of the interim image with reference to the locations on the interim image corresponding to the four peripheral alignment reference elements 122 without loss of generality.

[0033] Use or operation of the example image acquisition apparatus 100 running an image acquisition process which has devised the visual alignment guide 240 for the alignment reference device 220 is substantially identical to that described with reference to the alignment reference device 120 and the descriptions are adapted and applied mutatis mutandis without loss of generality. [0034] While the alignment reference devices 120, 220 and corresponding visual alignment guides 140, 240 have four peripheral alignment guiding elements, it should be appreciated that the number and distribution are merely for example. For example, there can be more than four or less than four peripheral alignment guiding elements and the peripheral alignment guiding elements may be symmetrical or non-symmetrical about an axis of the alignment reference devices 120, 220.

[0035] In an example image acquisition process, the processor is to process an interim or instantaneous image of a target object to determine acceptability. The target object includes the alignment reference device 220 to facilitate guided capturing of an image thereof which is the same as that of the alignment reference device 120 but does not have a central alignment reference element. In this process, the process will define properties of a reference image of the reference alignment reference device which will correspond to an interim image acceptable for acquisition. The properties may include selected range of geometric properties such as the dimensions of the reference image, lengths of the sides, and ratio between various sides. For example, the dimensions will provide useful data on whether the image to be captured is of an acceptable size in order to provide an acceptable level of resolution for applications. The ratios will provide information on possible distortion of the interim image that may affect the fidelity of the captured image. The process will store an image and/or the range of the properties of the reference image in a processor and then to evaluate various properties of the interim image of the alignment reference device 220 with reference to the corresponding range of properties of the reference image to determine acceptability.

[0036] As depicted in Figure 5, the interim image of the alignment reference device 220 is a quadrilateral (or a four sided-polygon) having a bottom side a, a top side b, a left side c and a right side d. The sides a, b, c, and d are respectively proximal to the bottom, top, left and right side of the display screen.

[0037] In a process to determine whether the angular tilting relative to the XY plane of Figure 3B is acceptable, the process is to examine the ratio between the length of side a and the length of side b on the interim image. If the ratio is within a pre-determined acceptable range of the side- length ratio of reference alignment reference device, the relative angular tilting is acceptable relative to the XY plane, which is also the plane of the display or the major surface of the apparatus. If the ratio is outside an acceptable tolerance range, a user will need to tilt the apparatus about the Y axis in a direction to bring the ratio to within the range and a visual guide will be generated to guide the user.

[0038] Likewise, the process is to examine the ratio between the length of side c and the length of side d on the interim image. If the ratio is within a pre-determined acceptable range of the side-length ratio of reference alignment reference device, the relative angular tilting is acceptable relative to the XY plane, which is also the plane of the display or the major surface of the apparatus. If the ratio is outside an acceptable tolerance range, a user will need to tilt the apparatus about the X axis in a direction to bring the ratio to within the range and a visual guide will be generated to guide the user. [0039] In addition, the length on one or more sides of the interim image alignment reference device 220 can be measured and then to compare with the range of lengths of a corresponding side or corresponding sides of the reference image of the reference alignment reference device to determine acceptability of image dimensions.

[0040] To determine the geometric properties of the interim image, the process may use image processing techniques to identify the four peripheral alignment guide elements 142 and to determine the length of the various sides a, b, c, d.

[0041 ] In addition to determining whether the interim image fulfils geometric requirements to be captured, the processor may also determine whether stability requirements are met when the geometric requirements have been met. In this regard, the process is to determine stability of the apparatus using data generated by the 3-axis accelerometer. If at the moment when the geometric properties are fulfilled and the stability level is within an acceptable range, the process will inform a user that the interim image is ready to be captured.

[0042] While the process has described measurement of geometric properties such as left-right tilting, up-down titling and relative distance, it should be appreciated that not all geometric properties need to be used at the same time and the geometric properties may be used selectively.

[0043] The above process when installed in the apparatus of Figure 1 comprising a processor will facilitate the apparatus to operate as an image acquisition apparatus according to the present disclosure without loss of generality. The image acquisition apparatus may obtain image for various applications such as identification, authentication, or for network access without loss of generality.

[0044] While the above disclosure has been made with reference to the various examples and applications, it should be understood that the examples and applications are non-limiting examples to facilitate understanding and should not be construed as scope restricting disclosure. For example, while the visual alignment guide and the corresponding alignment reference device are square and comprise many square components, it should be appreciated that a square shape is only used for simplifying illustrations and other shapes can be used without loss of generality.

Claims

1 . An image acquisition apparatus comprising a processor, an image capturing device and a visual alignment guide; wherein the visual alignment guide is for alignment with an alignment reference device on a target object; the processor is to provide feedback guidance to a user upon processing an interim or instantaneous image of the target object while the apparatus is aiming at the target object, such that the image of the target object is ready to be acquired by the image capturing device; and the feedback guidance is to guide the user to aim the image acquisition apparatus at the target object, such that alignment between the visual alignment guide and alignment reference device on the target object satisfies a set of predetermined alignment criteria.

2. An image acquisition apparatus according to Claim 1 , wherein the processor is to generate feedback guidance to inform a user that an image of the target object is ready to be captured when the alignment between the visual alignment guide and alignment reference device on the target object satisfies the set of predetermined alignment criteria, and the set of predetermined alignment criteria is to facilitate capturing of an image of the target object by the image capturing device which satisfies a prescribed quality of fidelity.

3. An image acquisition apparatus according to Claims 1 or 2, wherein the visual alignment guide comprises a graphical alignment device which is to be in a cooperative alignment with a corresponding graphical reference device on the alignment reference device of the target object when the alignment between the visual alignment guide and the alignment reference device on the target object satisfies the set of predetermined alignment criteria, and the processor is to generate feedback guidance to guide a user to control the image acquisition apparatus to approach said cooperative alignment.

4. An image acquisition apparatus according to Claim 3, wherein the graphical alignment device and the graphical reference device are to cooperatively devise a varying graphical feedback signal on approaching said cooperative alignment.

5. An image acquisition apparatus according to Claims 3 or 4, wherein the graphical alignment device and the graphical reference device are graphically complementary, and the feedback guidance comprises a visual guidance sign which is an instantaneous combinatorial product of the graphical alignment device and the graphical reference device, which provides instantaneous guidance information to a user.

An image acquisition apparatus according to any of Claims 3 to 5, wherein the feedback guidance is to convey deviation information from said cooperative alignment, and the deviation information comprises information on deviation in relative leveling and/or deviation in relative distance between the graphical alignment device and the graphical reference device.

An image acquisition apparatus according to any of Claims 3 to 6, wherein the feedback guidance is to provide guidance to a user to tilt and/or to move the image capturing apparatus relative to the target object.

An image acquisition apparatus according to any of the preceding Claims, wherein the visual alignment guide comprises a plurality of visual guide elements, and the visual guide elements are distributed to collectively define a set of geometric properties to facilitate alignment between the image capturing device and the target object to satisfy the set of predetermined alignment criteria.

An image acquisition apparatus according to any of Claim 8, wherein the set of predetermined alignment criteria includes at least a criterion on relative distance and/or at least the relative orientation between the image capturing device and the target object.

An image acquisition apparatus according to Claim 9, wherein the processor is to measure geometric properties of an image of the target object to determine the relative distance and/or the relative orientation.

An image acquisition apparatus according to any of Claims 8 to 10, wherein the set of predetermined alignment criteria includes at least a criterion on stability of the image capturing device relative to the target object.

An image acquisition apparatus according to Claim 1 1 , wherein the image acquisition apparatus includes an accelerometer to determine stability of the image capturing device.

An image acquisition apparatus according to any of the preceding claims, wherein the apparatus is to capture an image of the target object satisfying the prescribed quality of fidelity which is sufficient to facilitate verification of authenticity of the object.

An image acquisition apparatus according to any of the preceding claims, wherein the image acquisition apparatus includes a display device, and the display device is to show the visual alignment guide and the image of the target object while the visual alignment guide and the alignment reference device are approaching said cooperative alignment.

An image acquisition apparatus according to any of the preceding claims, wherein the image acquisition apparatus is part of an authentication apparatus for verifying authenticity of the target object.

An image acquisition process for operating an image acquisition apparatus to acquire an image of a target object having an alignment reference device, the image acquisition apparatus comprising a processor and an image capturing device, and the process comprising: devising a visual alignment guide which is for cooperative alignment with an alignment reference device on said target object,

- devising feedback guidance comprising a set of feedback guidance instructions to guide a user to aim the image acquisition apparatus at the target object so that the visual alignment guide and the alignment reference device will move towards said cooperative alignment upon following said set of feedback guidance instructions, and

- determining that the image of the target object is ready to be captured when the visual alignment guide and the alignment reference device are at said cooperative alignment.

An image acquisition process according to Claim 16, wherein the process comprises devising a set of feedback guidance instructions to correspond to a set of predetermined alignment criteria, and the set of predetermined alignment criteria is to facilitate capturing of an image of the target object by the image capturing device which satisfies a prescribed quality of fidelity.

An image acquisition process according to Claims 16 or 17, wherein the process includes devising a graphical alignment device on the visual alignment guide, and the graphical alignment device is to cooperate with a graphical reference device on the alignment reference device on the target object to collectively form a varying graphical feedback signal on approaching said cooperative alignment.

19. An image acquisition process according to Claim 18, wherein the graphical alignment device and the graphical reference device are graphically complementary, and the graphical feedback signal comprises a visual guidance sign which is an instantaneous combinatorial product of the graphical alignment device and the graphical reference device to provide instantaneous guidance information to a user.

20. An image acquisition process according to any of Claims 16 to 19, wherein the process is in the form of application software for installing onto a computing device, such as a mobile computing device having a built-in image capturing device and display.