GB2408876A

GB2408876A - Embedding location data in an image

Info

Publication number: GB2408876A
Application number: GB0328356A
Authority: GB
Inventors: Simon Turvey
Original assignee: Symbian Ltd
Current assignee: Symbian Ltd
Priority date: 2003-12-05
Filing date: 2003-12-05
Publication date: 2005-06-08
Also published as: GB0328356D0

Abstract

A method of recording an image in a camera, preferably a digital camera within a mobile phone, involves embedding in the image digital data representative of the location at which the image is recorded. The embedding may be achieved by varying the shading of pixels or by watermarking the image with the data. The data may be encrypted and may further include date, time and/or a unique identifier for the phone. The mobile phone may include a GPS, triangulation of mobile phone service provider or cell identification for location determination.

Description

IMAGE RECORDING METHOD AND APPARATUS

The present invention relates to a method for recording an image as digital data, 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 an 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 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 used to reproduce that image, either on a display screen or by printing out onto a suitable recording medium such as paper.

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 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 incorporate additional data into the image, such as 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 Image.

Photographic images are, in certain circumstances, used to provide photographic evidence of an event and although it is possible to incorporate additional information such as the date into the recorded image, it has not been known to record other types of data which may be considered useful to provide in certain situations, such as evidence of the location at which the image is captured.

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 device or which may be provided as a plug in accessory. This type of mobile phone is sometimes known as a camera phone. With this type of phone, it is possible to capture an image, including both still and video images, and then to send this 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 are almost considered to be an essential aspect of everyday life, whether for personal or business use.

However, there are certain situations where the availability of a camera on a person is considered undesirable, 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 may need to be visited by business personnel who require to have access to their mobile phones, but the unauthorized 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 authorization could be traced to some unique source, such as the device which has captured the image, the time and date at which the image was captured, or the location at which the image was captured.

Currently, there is an increasing need to provide location based services by way of a mobile phone. For example, a user of a mobile phone may be visiting a location which is unfamiliar to that user. That user may wish to determine, as an example, what garages are available and open for business in the vicinity of the location at which to buy fuel. With the latest generation of mobile phones it is perceived that this information can be downloaded to the mobile phone of the user, with the mobile phone, not the user, automatically providing the information provider with the location of the user so that the location of the open garages in the vicinity concerned can be provided. Mobile phones are, therefore, being provided with the ability to automatically sense their location and it has now been realised with the present invention that this ability can be used to advantageous effect when recording images.

Therefore, it is an object of the present invention to provide an improvement in the traceability of an image, and in particular 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 the image as digital data and embedding into the digital data information indicative of the location at which the image is recorded.

According to a second aspect of the present invention there is provided an image recording device comprising image recording means for recording an image as digital data, means for determining the location at which the image is recorded, and embedding means for embedding information indicative of the location into the digital data.

According to a third aspect of the present invention there is provided computer software arranged to cause a device according to the above second aspect 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.

In the description below the present invention is described with reference to a camera phone. However it is to be understood that the present invention may also be used with other types of devices which can capture an image and which are able to determine the location of the device when the image is taken. For example, the device may comprise a camera of standard form with locality detection.

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 s usually of relatively small size, typically about 5 to 1 Omm in diameter.

Furthermore, the object lens may be 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.

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 properly formatted the user can use the display screen of the camera phone as an 'electronic viewfinder' so that the image can be properly composed. However, it is equally possible that a user can covertly record images with relative ease because, in essence, the camera phone is regarded by many for its 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'.

As described above, with location based services a user may be supplied with information specific to the vicinity at which that user is located. Hence, for example, a user may request information about restaurants 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 information, such as FIND RESTAURANTS', only information relating to restaurants within a predefined distance to the particular location 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 cell in which the phone is being operated.

With the present invention, it has been recognised that this inbuilt ability of the mobile phone to sense its location can be used to advantageous effect to provide improved traceability of images when the mobile phone is in the form of a camera phone.

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 photodector, 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. 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 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 always considered to include the location at which the image is recorded by the camera phone, as determined through the use of one of the above mentioned location sensing techniques embodied into the device.

In addition to the location, it is envisaged that further information which may be usefully be used as characteristic information to facilitate image traceability can include an identifier, such as a numeric or alphanumeric sequence, which is unique to the device used to record the image. 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 could confidently supply his captured image to a 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.

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, the invention has been described with reference to a camera phone, but other types of image recording devices may be used, as long as the device is able to produce the characteristic data indicative of the image recording information. Additionally, 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 the image as digital data and embedding into the digital data information indicative of the location at which the image is recorded.

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 device used to record the image and/or the date and time at which the image is recorded.

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

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

8. A method according to any one of claims 5 to 7 wherein the further information is encrypted.

9. A method according to any one of the preceding claims comprising using a mobile phone incorporating a digital camera to record the image.

10. A method according to claim 9 wherein the mobile phone is arranged to comprise 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 at which the image is recorded.

11. An image recording device comprising image recording means for recording an image as digital data, means for determining the location at which the image is recorded, and embedding means for embedding information indicative of the location into the digital data.

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

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

14. A device according to any one of claims 11 to 13 comprising encryption means for encrypting the embedded information.

15. A device according to any one of claims 11 to 14 wherein the embedding means is arranged to embed into the digital data further information for identifying the device and/or the date and time at which the image is recorded.

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

18. A device according to any one of claims 16 or claim 17, or claim 15 when appendant to claim 14, wherein the encryption means is arranged to encrypt the further information.

19. A device according to any one of claims 11 to 18 comprising a mobile phone incorporating a digital camera to record the image.

20. A device according to claim 19 wherein the means for determining the location at which the image is recorded 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.

21. Computer software arranged to cause a device according to any one of claims 11 to 20 to function in accordance with a method according to any one of claims 1 to 10.