WO2006064171A1

WO2006064171A1 - A method of recording an image with a mobile phone

Info

Publication number: WO2006064171A1
Application number: PCT/GB2004/005237
Authority: WO
Inventors: Simon Turvey
Original assignee: Symbian Software Limited
Priority date: 2004-12-14
Filing date: 2004-12-14
Publication date: 2006-06-22

Abstract

An image is captured as digital data using a mobile phone incorporating a digital camera. The mobile phone is able to determine the location at which the image is captured using a technique used by the phone to provide location-based services to a user. Information indicative of the location is embedded into the digital data, preferably using watermarking and encryption techniques. Further information, such as a unique identifier for the phone and the date and time at which the image is captured, may also be embedded into the digital data.

Description

A METHOD OF RECORDING AN IMAGE WITH A MOBILE PHONE

The present invention relates to a method for recording an image as digital data using a mobile phone, and in particular to a method for embedding information into the recorded data to facilitate traceability of the recorded image.

It is known to capture images by using a camera to selectively expose photographic sheet or roll materials having a chemically based light sensitive coating. The captured image is then fixed into the light sensitive coating, as either a positive or a negative version of the image, using chemical development techniques. With these more traditional image capturing techniques it has been possible to record also certain data with the captured image, such as the date on which the image was captured. This additional data can be provided by exposing the light sensitive coating to a light image of the required data, such as by using a small light emitting diode date and time display arranged within the camera at the time the image is captured, or by recording the data onto a narrow magnetic stripe arranged along an edge of the photographic material, which is subsequently read and used to print the required data onto a paper based form of the recorded image. In either case the additional data is clearly visible on the medium used to portray the captured image.

In recent years, there has been extremely rapid growth in the use of digital cameras. In this type of camera, a photo sensor converts light reflected from a visual image into an electrical signal, and this electrical signal is subsequently converted into a digital signal. This digital signal is then stored into a recording medium, such as a flash memory incorporated in the camera. In essence, the captured image is stored as digital data which can be read to reproduce that image, either on a display screen or by printing onto a suitable recording medium such as printing onto paper using an ink jet printer. The use of digital cameras enables a user to personally and easily preserve or process the captured image in various ways through the use of a personal processing device, such as a personal computer (PC). The digital cameras themselves are relatively complex items of equipment, but as the quality of the reproduced image has improved, and the market penetration for this type of device has increased, they have become relatively less expensive to manufacture and therefore purchase, notwithstanding the improvement in the quality of the captured image.

Additionally, with digital cameras, the user is able to select from a variety of modes for photographic operation and because the image is held as digital data, it is relatively easy to add additional data to the data representing the actual image, such as additional data representing the date on which the image was captured. Furthermore, it is also possible to store this digital data in such a way that the user is able to select, each time an image is viewed or printed, whether or not that data is to appear within the displayed or printed image.

Photographic images are, in certain circumstances, an extremely useful way to provide recorded evidence of an event. With digital cameras it is now possible to record the date on which an image is taken as data embedded in and forming part of the digital data representing the recorded image.

More recently, a new generation of mobile phone has become available with a wide variety of functionality, and the mobile phone service providers are providing additional services to support the additional functionality provided by these devices. Increasingly, these phones are being provided with digital cameras, which may be integrated into the handset per se or which may be provided as a plug in accessory. This type of mobile phone is, increasingly, becoming known as a 'camera phone'. With a camera phone, it is possible to capture an image, both still and video images, and then to send that image to a third party using a messaging service of the mobile phone network service provider. Mobile phones are now in very widespread use and, for many users, are considered to be an essential aspect of everyday life. This is particularly so for those using these devices for business use because continuous communication can be maintained whether at or away from the office on business travel. This type of user often uses a new generation of mobile phones, known as smart phones. These phones are known as smart phones because they rely upon an operating system for their operation and they are capable of providing additional functionality through the use of software applications which may be downloaded onto the devices by a user: smart phones are rapidly becoming more popular than Personal Digital Assistants (PDAs) because they provide the flexible personal computing functionality of a PDA with the communications ability of a mobile phone in a single compact device. These smart phones also tend to be provided as standard with an inbuilt camera because they are ideally suited to the processing and storage of the digitally recorded images.

However, there are certain situations where the availability of a camera on a person is considered undesirable in a business environment, so a conflict can arise between the need to carry a mobile phone for business and the need to exclude the presence of a camera capable of recording images. For example, new product development establishments usually need to be visited by business persons, such as suppliers or other external service providers, who require to have access to their mobile phones to enable communication back to their home company, but the unauthorised presence of a camera in such an establishment, which might possibly giving rise to the recording of images of new products under development prior to their release into the market place, is considered to be highly undesirable.

The use of such camera phones for industrial or commercial espionage is not unknown and it could therefore be extremely beneficial if an image of a confidential subject captured on such a phone without authorisation could be traced to some unique source, such as the device which had been used to capture the image, because then it could be confirmed whether or not a particular device, and whether or not the particular user of the particular device, had recorded the unauthorised image.

Mobile telephone handsets are provided with a unique identity, known as the International Mobile Equipment Identity (IMEI). The IMEI numbering system is a 15 digit unique code that is used to identify the mobile phone to the network to which it is connected or trying to connect. When a mobile phone is switched on, this unique IMEl number is transmitted and checked against a database of blacklisted or greylisted phones in the EIR Equipment ID Register (EID) of the network. In this way the EIR determines whether the phone can log onto the network to make and receive calls. However, with the present invention it has been realised that the IMEI can also be used to advantage to provide a unique identifier of a camera phone used to record an image, which, if necessary, can be traced through the EID registers of the network providers

Therefore, it is an object of the present invention to provide an improvement in the traceability of an image captured using a mobile phone incorporating a digital camera.

According to a first aspect of the present invention there is provided a method of recording an image, the method comprising recording an image as digital data using a mobile phone having an image recording capability, and embedding into the digital data information indicative of the International Mobile Equipment Identity (IMEI) number of the mobile phone used to record the image.

According to a second aspect of the present invention there is provided a mobile phone arranged to operate in accordance with a method of the first aspect.

According to a third aspect of the present invention there is provided computer software for causing a mobile phone to operate in accordance with a method of the first aspect. An embodiment of the present invention will now be described, by way of further example only, with reference to the accompanying drawing which illustrates a flow chart for recording an image with a mobile phone incorporating a digital camera in accordance with an embodiment of the present invention.

With a camera phone, the user can operate the device as a 'normal' mobile phone to effect mobile communications. These devices are however fitted with an integral or plug in digital camera having an objective lens and some form of photo sensor, such as a charge coupled device, for capturing an image. With a camera phone of the type having an integral camera, the camera objective lens is usually provided on the rear of the camera casing. The objective lens is usually of relatively small size, typically about 5 to 10mm in diameter. Furthermore, the object lens is often surrounded by an external design feature which is selected to integrate with the general design theme for the phone casing. These integral cameras are therefore relatively unobtrusive and, unless the particular model of phone is well known to a person, it can be very difficult to discern that the mobile phone being carried by an individual is in fact a camera phone and therefore capable of recording images.

Because the images are recorded digitally, as long as the device has sufficient memory, many records of an image may conveniently be stored for subsequent editing or use by the user. When an image is to be recorded the user can use the display screen of the camera phone as an 'electronic viewfinder' so that the image to be recorded can be viewed and properly composed. However, it is equally possible that the phone user can covertly record many images with relative ease because, in essence, the camera phone is regarded by many for its principal ability to be used as a mobile communications device and not as a device which can be used for recording images.

It is known that there is an increasing demand for mobile phone service providers to provide what are increasingly becoming known as location based services'. One of the proposed uses for location based services is to supply a user with information specific to the vicinity at which that user is located. Hence, for example, a user may request information about restaurants or other services in a town or city which the user is visiting.

To effect location based services, the mobile phone is provided with the ability to sense its location so that when the user makes a request for 'local¹ information, such as 'FIND RESTAURANTS', only information relating to restaurants within a predefined distance to the particular location at which the user is located at the time the request is made are provided to the user. A variety of techniques may be used by the mobile phone to sense its location. Examples are global positioning system, triangulation of mobile phone service provider base stations, or identification of the particular cell in which the phone is being operated. Any combination of these various positioning techniques may also be used.

Unlike digital cameras, which from the onset have been designed principally to record digital images, either still or moving images, mobile phones are designed principally for use as mobile communications devices. As such, mobile phones each include a unique identifier which is actively used to determine whether or not a device should be able to operate on the network of a network provider. This unique identifier is known as the International Mobile Equipment Identity Number (IMEI) for the device. The IMEI numbers are allocated to device manufacturers under a very tightly controlled and rigid industry wide structure.

Only manufacturers or their authorised representative, who are both very precisely defined, are eligible to obtain block IMEI number allocations, and applications for such allocations are refused if there is any doubt whatsoever as to the validity of the applicant.

The manufacturer of the mobile phone must factory set the IMEI number in the permanent memory of the handset and it must be tamper resistant. In practice, this means that it is virtually impossible to change the IMEI for a device outside the place of manufacture. Hence, any camera phone carries a unique identifier and thus can be regarded as being unlike any other type of image recording device.

With the present invention, it has been recognised that this unique identifier of the mobile phone can be used to advantageous effect to provide improved traceability of images when the mobile phone is used to record images.

With a camera phone according to the present invention, the image to be recorded is captured in the usual manner, as can be seen from step 2 of figure 1. The image, which at this stage is an analogue signal output from the camera photodetector, is then subjected to analogue to digital conversion and the digital data created is stored into memory. Typically, this memory will comprise of flash memory embodied in the camera, or a memory card that is plugged into an appropriate memory card socket provided on the mobile phone body. This process is shown as steps 4 and 6 in figure 1.

At step 8, a decision is made as to whether or not the image is to be watermarked. It is envisaged that in a preferred form of camera phone according to the present invention, the device will automatically default to watermarking any digital image created with the device and that the device will not enable a user to de-select this option. In other words, watermarking is effected for all images recorded with the device to further facilitate traceability of recorded images.

At step 10 the device determines the characteristic data to be watermarked into the image. This characteristic data may comprise a variety of options but is arranged to always include the IMEI number of the camera phone.

In addition to the unique IMEI identifier, it is envisaged that further information which may be usefully be used as characteristic information to facilitate image traceability can include location based data which is indicative of the location at which the image has been recorded. The location may be sensed using any of the techniques outlined above. Furthermore, the date and time at which an image is recorded can also usefully serve as further information within this characteristic information.

Because this characteristic information is to be used to authenticate an image, it is preferable that it is encrypted to hinder any subsequent attempt to falsify this characteristic data. Hence, at step 12 it is decided whether or not the characteristic data is to be encrypted. Again, in common with the decision as to whether or not the image is to be watermarked, the encryption of the characteristic data is shown as an optional process step in the flow chart shown in figure 1. However, in a preferred form of the present invention, encryption of the characteristic information is always arranged to occur and, again, this may or may not be provided as a user selectable option. Therefore, at step 14 the characteristic information is encrypted. Any encryption technique may be provided for this purpose, such as the use of a private key loaded into the device. The characteristic information is then embedded at step 16 into the digital data representative of the captured image. The digital data including the embedded characteristic information is then encoded to effect image compression in order to increase the number of images that may be recorded into the memory of the device, as shown by step 18. The compressed image, including the characteristic data, is then recorded into memory. This is shown as step 20 in figure 1.

Any suitable compression technique may be used to encode the image and characteristic data, such as the JPEG (Joint Photographic Export Group) compression technique. However, it should be realised that other image compression techniques may also be used.

All of the above process steps may be controlled in the device by the operating system embodied in and used to control the device, including the allocation of the secret key to effect encryption. The identification of this secret key need not be made known to the user. It can be appreciated from the above description that by embedding characteristic data, which includes the location of image capture, and preferably a unique identifier for the device capturing the image, and the date and time at which the image is captured, in an encrypted form into the digital data representing the image, the authenticity of a captured image can be facilitated.

Hence, taking as an example a camera phone user involved in a motor accident with a third party, it would be possible for the user to capture an image at the accident scene at the time of the incident and this image might be required to be relied upon by the camera phone user to corroborate events claimed to have taken place, such as the point of vehicle impact, tyre marks on the road surface etc. By embedding encrypted characteristic information into the image using the process steps shown in figure 1 , the user can confidently supply his captured image to the third party, but with the knowledge that the third party is able to view the recorded scene but is not able to tamper with the image because of the embedded characteristic data, and in particular the IMEI number because that number is unique to the camera phone of the user and is not known to the third party.

Preferably, the characteristic data may be embedded into the digital image data by modifying the shading of pixel information of the digital data, in this way degradation of the recorded image arising from the embedded data can be minimised, such that there is no discernible reduction in the image quality, when viewed.

Although the present invention has been described with reference to a particular embodiment, it will be appreciated that modifications can be effected whilst remaining within the scope of the present invention as defined by the appended claims. For example, in the process steps described with reference to figure 1 , only the characteristic data is encrypted. However, it is also possible to embed non-encrypted characteristic data and then to encrypt the image data and characteristic data as a single process step.

Claims

1. A method of recording an image, the method comprising recording an image as digital data using a mobile phone having an image recording capability, and embedding into the digital data information indicative of the International Mobile Equipment Identity (IMEI) number of the mobile phone.

2. A method according claim 1 wherein the information is embedded by modifying the shading of pixel information of the digital data.

3. A method according to claim 1 or 2 wherein the information is embedded using a watermarking technique.

4. A method according to any one of claims 1 to 3 wherein the information is encrypted.

5. A method according to any one of the preceding claims comprising embedding into the digital data further information for identifying a location and/or the date and time at which the image is recorded.

6. A method according to claim 5 wherein a global positioning system, triangulation of mobile phone service provider base station, or mobile phone cell identification technique is used to determine the location at which the image is recorded.

7. A method according to claim 5 or 6 wherein the further information is embedded by modifying the shading of pixel information of the digital data.

8. A method according to claim 5, 6 or 7 wherein the further information is embedded using a watermarking technique.

9. A method according to any one of claims 5 to 8 wherein the further information is encrypted.

10. A mobile phone comprising image recording means for recording an image as digital data, and embedding means for embedding information indicative of the International Mobile Equipment Identity (IMEI) number of the mobile phone into the digital data.

11. A mobile phone according claim 10 wherein the embedding means is arranged to embed the information by modifying the shading of pixel information of the digital data.

12. A mobile phone according to claim 10 or 11 wherein the embedding means is arranged to embed the information using a watermarking technique.

13. A mobile phone according to any one of claims 10 to 13 comprising encryption means for encrypting the embedded information.

14. A mobile phone according to any one of claims 11 to 13 further comprising means for determining the location of the mobile phone, and wherein the embedding means is arranged to embed into the digital data further information for identifying the location and/or the date and time at which the image is recorded.

15. A mobile phone according to claim 14 wherein the means for determining the location of the mobile phone uses any one or more of a global positioning system, triangulation of mobile phone service provider base station, or mobile phone cell identification technique to determine the location.

16. A mobile phone according to claim 15 wherein the embedding means is arranged to embed the further information by modifying the shading of pixel information of the digital data.

17. A mobile phone according to claim 15 or 16 wherein the embedding means is arranged to embed the further information using a watermarking technique.

18. A mobile phone according to any one of claims 15, 16 or claim 17, wherein the encryption means is arranged to encrypt the further information.

19. Computer software arranged to cause a mobile phone according to any one of claims 10 to 18 to function in accordance with a method according to any one of claims 1 to 9.