GB2460580A

GB2460580A - Power management using image capture

Info

Publication number: GB2460580A
Application number: GB0917181A
Authority: GB
Inventors: Peter Hopton; Joe Denby
Original assignee: VERY PC Ltd
Current assignee: VERY PC Ltd
Priority date: 2009-09-30
Filing date: 2009-09-30
Publication date: 2009-12-09
Anticipated expiration: 2029-09-30
Also published as: GB2460580B; GB0917181D0

Abstract

A method of waking an item of electrical equipment (e.g. a computer) from a low power sleep state in response to capturing an image of a user obtained from a digital camera (e.g. a web-camera) is generally described. The invention in particular relates to a method of operating an item of electrical equipment, and optimising power consumption. The method includes capturing a succession of digital images and analysing at a first frame analysis rate to determine if a user is positioned to use the equipment, if a user is detected as a result of the digital image analysis, running a user detection algorithm at a second, relatively higher frame rate and, if a user is detected as present, selecting a given operational mode (e.g. waking a computer). Facial recognition may be used to detect the user. The computer may also be sent to sleep (power save mode) in response to not detecting a face for a given time. More than one camera may also be used.

Description

IMPROVED POWER SAVE METHOD AND APPARATUS FOR

ELECTRICAL EQUIPMENT

Field of the Invention

The present invention relates to power saving for electrical apparatus.

Background to the Invention

In conventional electrical apparatus, for example personal computers, domestic appliances and the like, it is known to have "standby" or "power saving" modes of operation, in which, when a user fails to interact with the apparatus for a pre-determined time, for example does not enter any mouse actions or keyboard instructions, the apparatus temporarily powers down one or more components in order to save power.

Referring to Figure 1 herein, there is shown a conventional personal computer operating a known SLEEP mode managed by its operating system.

Known computers operate a screen power down after a pre-determined period, which is user selectable from a control panel part of the operating system.

Similarly, some known computers operate a full power save mode after a pre-determined period of non-use, that is, a pre-determined period after the last keystroke or user interaction with the computer. For example, in Microsoft Vista� operating system, the settings of the "energy star" "sleep" mode can be preset. A timing parameter for turning off the monitor display can be set independently of * 0*.

: the pre-determined period for putting the Central Processing Unit (CPU) to sleep. * S.. * S

In the Microsoft Windows XP� operating system, there are separate "sleep" ***.

and "hibernate" modes. In the "sleep" mode, the system state is saved to a *�**'* * Random Access Memory (RAM), and the processor is restricted to a reduced *.*. number of instructions per second, compared to its maximum possible rate of instructions per second. In the "hibernation" mode, the system state is saved to a hard disk, and the processor is turned off altogether. Recovering from the "sleep" P2022.spec mode takes less time than recovering from the "hibernate" mode, because recovery of the system state from RAM is quicker than recovery of the system state from hard disk. In each of these modes, the processor has reduced power consumption, resulting in power saving compared to normal running of the processor. However, in the "sleep" mode the processor is still running on reduced power consumption, and is therefore active.

In the sleep and hibernate modes, the system state is stored and is not lost, so that on recovering from the sleep or hibernate modes, the user can carry on using the computer without the need to reboot. Because there is no reboot, the PC can respond much more quickly compared to a power down and reboot operation.

On the other hand, when the computer is turned off altogether, the processor is shut down, the system state is stored to hard disk, power is removed altogether from the mother board, and the computer may be disconnected completely from the AC mains supply. To turn on the computer, mains power is applied via the "on/off' switch of the computer and the computer boots up, activated by the BIOS of the computer. Boot up of the computer is time consuming and can take of the order of up to I to 3 minutes. In the shut down mode, all applications are closed, and any work in progress within applications needs to be stored to hard disk. On boot up, the system state reverts to its default system state, applications need to be restarted, and files for work in *: progress need to be reopened manually.

***S 25 In the known Windows Vista� operating system, there is a "hybrid sleep state" which takes the best aspects of the sleep and hibernate modes which * existed separately in Windows XP. In the hybrid mode, the system state is stored both in RAM and on disk, so the system state is not lost if power is removed from the computer completely. The system is then suspended in a low powered sleep state for a period of time, and when a user returns and "wakes" P2022.spec the machine, for example by activating a key or moving a mouse, the system is restored from RAM. Responsiveness to the user from a sleep mode is relatively fast. However, if for some reason the power is lost, for example if the PC is unplugged from the mains, the system can still resume from the hibernate state, since the system state image has been previously saved to the disk with all context and data intact.

It is an ongoing objective of personal computer development to reduce the overall power consumption of the computer, for the primary reasons of: (a) reducing CO2 emissions by lower power usage; (b) reducing total cost of ownership, by virtue of reducing overall power consumption; (c) in the case of portable computers, increasing time between battery recharge.

These three objectives are complimentary to each other and are all improved by achieving lower overall power consumption by use of "sleep" modes.

However, the benefits of reduced power consumption need to be balanced against the disadvantages of such "sleep" modes, which are primarily an increased response time to a user, compared to when the computer is in its normal operating mode.

Summary of the Invention

According to a first aspect there is provided a method of minimising power consumption of an item of electrical equipment, said method comprising: *.S, S.....

capturing a succession of digital images; * S. * S S * 0* *. 30 analysing said succession of digital images at a first frame analysis rate to determine if a user of said equipment is present; P2022spec if a said user is not detected as a result of said digital image analysis at said first frame analysis rate, continuing to monitor said images at said first frame analysis rate; if a user is detected as a result of said digital image analysis at said first frame analysis rate, capturing a further succession of digital images; analysing said further succession of digital images at a second, relatively higher frame analysis rate to determine if said user is present; and in response to a user being detected as present as a result of said analysis at said second relatively higher frame analysis rate, selecting one of a plurality of possible operational modes of said equipment.

According to a second aspect there is provided a power management component for managing power usage of an item of electrical equipment, said power management component comprising: a digital camera capable of capturing a succession of digital images; a digital image analyser capable of analysing said digital images to determine if an image of a user is present in said digital images; and * S S 5 *. 25 signal generator means for generating an activation signal to transition said electrical equipment into one of a plurality of possible predetermined operational modes in response to a signal generated by said digital image analyser; * I wherein said digital image analyser operable to: * 30 S..

P2022.spec -5.-analyse a succession of digital images at a first frame analysis rate to determine if an image of a user is present in said captured digital images; if a user is detected in at least one of said captured digital images, said analyser operates at a second, relatively higher frame analysis rate, to determine whether the image of a user is present in one or more successively collected said digital images.

The aspects include a carrier having thereon a computer program comprising computer implementable instructions for causing a computer to operate according to the method of the first aspect.

The aspects include a computer program on a carrier and comprising computer executable instructions for causing a computer to carry out the method is as set out in the first aspect.

The aspects include a computer readable medium having a program recorded thereon where the program is to make a computer execute procedure to carry out the method as set out in the first aspect.

Other aspects are as set out in the claims herein.

Brief Description of the Drawings

*: For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: *:*:: Figure 1 illustrates schematically a conventional personal computer running :. 30 a conventional operating system and having a known SLEEP mode; P2022.spec Figure 2 illustrates schematically a "green" computer incorporating an image capture device and face detection component according to a specific embodiment of the present invention; Figure 3 illustrates schematically components of the green computer of Figure 2; Figure 4 illustrates schematically components of the green computer of Figure 2 herein for monitoring if a user is present and activating a SLEEP mode; Figure 5 illustrates schematically operation of the green computer in a monitor "ON" state; and Figure 6 illustrates schematically operation of the green computer in a monitor "OFF" state.

Detailed Description

There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to

: unnecessarily obscure the description.

S * 25 S...

In this specification, the term "sleep" mode when used with reference to a computer includes, but is not limited to, the S3 mode under the computer * Advanced Configuration and Power Interface specification (ACPI) revision *:*:: number 4.0 published on June 16, 2009.

S ***

P2022.spec Figure 2 herein illustrates schematically in perspective view, a computing device 200 equipped with a power management component for managing power consumption of the equipment.

The computing device comprises a casing 201 containing a power supply unit, a processor, a processor motherboard containing a bus; one or more hard drives, one or more CD or DVD drives, one or a plurality of ports, for example USB ports, or memory card ports; a visual display monitor 202, keyboard 203, and a mouse or track ball device.

The equipment is also provided with a digital camera 203 which is positioned on the device with a filed of view opposite a user, such that the camera can capture an image of the user's face, when the user is positioned in a working position in front of the computer.

Referring to Figure 3 herein, there is illustrated schematically components of the computer equipment of Figure 2 herein.

The computer equipment comprises: a random access memory 300; a central processing unit 301; one or more hard disk drives 302 for storing data; a BIOS 303; a digital camera 304; a monitor display unit 305; one or a plurality of input/output ports 306; a keyboard 307; and a pointing device 308, such as a mouse or track ball. Components are contained within a casing, which also is : provided with a power supply unit or battery. In the general sense, the computing *::::* 25 device may be a laptop type portable computing device, or a mains powered work station device as shown in Figure 2. S...

S

S.....

* The computer is capable of adopting various states as set out in the ACPI *::: standard as follows.

I

P2022.spec The ACPI specification defines seven states (called global states) which an ACPI compliant computer system can be in. These include: GO(s) the device is working Gi Sleeping, which subdivides into the four states Si through S4 in which: Si: all processor caches are flushed, and the CPU stops executing instructions. Power to the CPU is maintained and devices which do not indicate that they must remain on may be powered down.

S2: the CPU is powered OFF.

S3: commonly referred to as standby, sleep, or suspend to RAM.

RAM is still powered.

S4: hibernation or suspend to disk. All content of main memory is saved to non-volatile memory such as a hard drive and is powered down.

G2(S5) SOFTOFF. G2 is almost the same as G3 mechanical OFF, but some components remain powered so the computer can "wake" from input from the keyboard, clock, modem, LAN or USB device. * * * ** *

*.,. 25 G3 Mechanical OFF: The computer's power consumption approach is close to zero to the point that the power cord can be removed and the system is safe for disassembly and typically, only the real time clock is running from its own ***** * internal small battery. * S. * S S * S.

Referring to Figure 4 herein, there is illustrated schematically, components of the computing device of Figures 2 and 3 herein. The computing device P2022.spec comprises a camera 400 for capturing digital images of the user, the camera being positioned such that its field of view covers a position relative to the computing device which a user would occupy when using the computing device; an energy management module 401; a monitor driver 402 for driving a visual display device; and a monitor visual display device 403.

Overall power consumption management of the computer is as follows.

When a user is using the computer, there are key stroke inputs and pointing device inputs as a result of interaction with the user. So long as these inputs continue, then the computer remains in an ON state up to a pie-determined time from the time of the last such input from the human user.

After a pre-determined time from the last interaction with the user, the computer adopts a SLEEP mode in which the monitor screen is turned off to save power. In this mode, the CPU operates in a reduced speed of instruction per second to save power, but is not turned off corresponding to the G3 -S3 sleep mode.

If there is no further interaction from a user for a further (second) pre-determined time period, then the computer may adopt a HIBERNATE mode, corresponding to the ACPI G3 -S4 mode.

. : At any time, the computer can be woken up from either the SLEEP mode or *::* 25 the HIBERNATE mode, by a user input, for example activating a key stroke, or activating a mouse input.

S

**SSSS When the computer adopts a SLEEP or HIBERNATE mode, the monitor is turned off to save power.

S

P2022.spec Software turns the monitor off after a user has not been detected for a preset period of time. The Software moves the computer to a different, lower power consumption mode after an even longer period of absence of a user.

Once the computer has been in the SLEEP mode for a predetermined period, with no user being detected as present, then the computer adopts a lower power usage mode, the HIBERNATE mode. In the HIBERNATE mode, power consumption of the computer as a whole is lower than in the SLEEP mode.

Running in parallel with the above modes of operation, the camera which has a field of view covering the location position of the user relative to the computer, which the user would adopt when using or about to use the computer, captures a series of images. When the user is sat in front of the screen facing the screen, the user will be in the field of view of the camera, which may be for example a web camera integrated into the monitor or otherwise into the computer apparatus, or which may be a peripheral device such as an after market web camera. The default image capture rate of the camera is relatively low, in order to save processing power and thereby reduce energy consumption. Typically, the background rate of image capture and image analysis is in the range 0.5 to 4 frames per second, and preferably in the range 0.5 to 2 frames per second. A face detection algorithm is applied to the captured images to determine if the user is in position to use the computer and to wake the computer up.

To achieve low power consumption, a relatively low frame analysis rate should be selected during the SLEEP mode, however having a relatively low frame analysis rate reduces the responsiveness of the computer to the user being present, when waking from the SLEEP mode.

S.....

S S

A problem occurs in that when the computer is in a SLEEP mode and is analyzing digital images at a relatively lower frame rate, occasionally, due to the imperfections in the face recognition and detection algorithm, false positive face P2022.spec detection occurs in a digital image, when in fact there is no face present. The occurrence of false positive face detections may bring the apparatus out of SLEEP mode, or prevent the apparatus from entering sleep mode, resulting in the apparatus being either continuously ON or repeatedly woken up from sleep mode, when in fact no user is present.

In order to overcome this problem, the apparatus is modified to operate as follows.

The default image capture rate of the camera and the default image analysis rate of the face detection component is set at a relatively low value, for example 0.5 to 4 frames per second, and preferably in the range 0.5 to 2 frames per second. When the face detection algorithm detects a face in an image, that could either be because a user is present in front of the equipment, or because is there is a false face detection, due to the imperfections in the face detection algorithm.

If the face detection algorithm positively identifies a face from the image, when running in the low frames rate mode, then the face detection algorithm immediately switches to a higher frame rate mode to check that the face is still present. By entering a second mode of operation in which the face detection algorithm processes a higher rate of frames per second, typically equal or greater than 10 frames per second, and ideally in the range 20 to 40 frames per second, e.

.. : the algorithm can quickly confirm whether the original face detection was a spurious detection (false alarm) or a genuine detection. The purpose of this second mode of face detection is to act as a check and confirmation that the ** . . . . . . initial face detection was not a false detection. Performing the confirmation or * checking operation at a higher rate of frames per second improves the response *:*:: time of the computer when waking up from a SLEEP mode, but with the penalty * 30 that, for a brief period of checking time, a relatively higher CPU processing power P2022.spec and therefore slightly higher energy consumption is incurred compared to if the images were processed at the lower frame rate.

From the usability perspective, "wake up" response times need to be as low as possible, and to achieve this, the camera would capture images at a high frame rate, typically in the range 20 to 40 frames per second, and each frame would be analysed at the same frame rate, for example 20 to 40 frames per second. However, digital image analysis and face recognition involves intensive use of the processor, and power consumption of the processor is approximately proportional to utilization of the processor. Since the purpose of placing the computer in a SLEEP mode is to save energy and reduce power consumption, having a relatively high frame analysis rate during the sleep mode diminishes the power saving advantage of placing the computer in a SLEEP mode, If the face detection algorithm were to run at 20 frames per second or more permanently then the potential power saving of entering the sleep mode would be cancelled by the additional power requirement of the processor running the face recognition algorithm.

Therefore, on encountering a positive face detection, the image capture rate of the camera and the frame analysis rate of the face detection algorithm increases to a second, relatively higher frame rate, for example in the range equal or greater than 10 frames per second and preferably in the range of 20 to frames per second. * * . 0* *

*.** . . The camera and face detection algorithm are operated at this second higher frame rate for a short period, in order to verify whether the original detected face (detected at the lower frame rate) was a true detection or a false positive * detection. A sequence of digital images are captured and analysed at the *:*::* second relatively higher frame rate, until a sufficient sample of images have been analysed. The number of samples of images can be preset within the apparatus at the time of manufacture of the equipment, or can be user settable. Typically, 2 P2022.spec to 5 separate images may be set to be the pie-determined number, so that if for example 5 successive images each give a positive face detection result when processed through the face detection algorithm at the higher frame rate, then the face detection is taken as verified positive and the equipment is brought out of s the SLEEP mode.

However, if after having identified a first positive face detection at the lower frame rate, the required number of successive higher frame rate digital images do not contain positive face recognition, i.e. have not passed the pie-determined threshold, for example if there is insufficient face detection in the subsequent number of preset images, then the original detection is taken as a false positive identification, and the equipment remains in SLEEP mode.

Using this method, the utilization of the face detection algorithm is is minimized so that most of the time, image capture and operation of the face detection algorithm operate at the first, relatively lower frame rate, but for a small time after a positive face identification, the camera and face detection algorithm operate at the second relatively higher frame rate in order to verify and check the validity of the original face detection event.

After a positive or negative verification at the second, higher frame rate, the image capture rate and image analysis rate then revert to its default relatively lower rate, irrespective of whether the apparatus is in the sleep mode, or in fully *.S *..* : operation mode. I... * 2 **& *

Therefore, the computer is continuously checking image frames at a low frame processing rate, which is more economical on power, to detect if a users *êS*U * face is present in front of the computer. If a user's face is detected, then the computer adopts a higher frame processing rate to check that the original face detection is a true face detection, not a spurious detection or a false detection. If the face detection algorithm confirms that a face has been detected during the P2022.spec higher frame processing mode, then the computer is awoke from its SLEEP condition. However, if the face detection algorithm is unable to confirm that a face has been detected, during the higher frame rate processing mode, then the computer continues in its sleep mode, waiting for a positive identification of a users face.

Running the face detection algorithm in two modes of operation, one at a slow rate of frames per second and the other at a higher rate of frames per second may have an advantage that during the low rate of frames per second analysed, the power consumed by the processor is relatively low, thereby saving energy, but also that any spurious false detections which occur in the low frame rate analysis mode are quickly checked by repeating the analysis on successive image frames at a much higher frame analysis rate, thereby improving the responsiveness of a computer to wake from the SLEEP mode, when a user is confirmed as being present. The dual frame rate mode of operation optimizes achieving low power consumption, which achieving high responsivity times when returning from a sleep mode.

Referring to Figure 5 herein, there is illustrated schematically processes for operation of the energy saving component when the monitor is in an ON state.

In process 500, the face recognition and detection algorithm operates in continuous mode. The algorithm analyses digital images taken by the camera, at J4** a default relatively lower rate typically in the range 0.5 to 4.0 frames per second, 25 with the exact rate of frames per second being user settable and preferably between 0.5 and 2 frames per second. In process 501, where the face detection algorithm makes a positive identification of the face i.e. a face is detected, then in * S...

* process 503, a timer is reset, and the face detection algorithm continues to .. operate at the first (default) frame detection rate.

P2022.spec Where the face detection algorithm does not detect a face, then a timer proceeds to increment in process 502 until the time reaches a pre.-determined count time set as a number of seconds 504. Until the preset number of seconds has lapsed, the face detection algorithm proceeds as before, analysing captured images at the relatively lower default rate of 0.5 to 4 frames per second, and preferably 0.5 to 2 frames per second, until it makes a positive face detection.

If the timer exceeds the pre-determined number of preset seconds in process 504, without a face having been detected in front of the monitor, then in process 505, the monitor is powered down to a power save mode. That is, the monitor screen is turned off to save power.

In process 506, the power save component determines whether security settings have been activated for the computer. If a security setting has been activated, then in process 507, the computer is locked, and then becomes only usable upon entry of a password or other security device, for example activation of a biometric security sensor. If in process 506, a security setting has not been activated, then in process 508, the processor is powered down and the computer moves to an OFF state. The OFF state 508 may correspond to the G2(S4) SOFTOFF state in the ACPI standard.

If security is set in process 506, then the computer is locked, and the motherboard is powered down to OFF state 508.

In the "OFF" state, the face detection algorithm continues to run at a relatively low frame rate, as described previously. * * S...

Referring to Figure 6 herein, there is illustrated schematically processes carried out by the energy saving component, when the monitor is in an OFF * 30 state.

S

P2022.spec In process 600, face detection component runs the face detection algorithm, at the relatively lower frame rate of 0.5 to 4 frames per second, and preferably 0.5 to 2 frames per second. As long as there is no face detected, then the timer continues to count up time increments in process 602. As long as no face is s detected, and as long as the timer does not exceed a preset SLEEP time setting in process 603, then the face detection algorithm continues to operate, and fully continues to check for faces in the captured images, at the relatively lower frame analysis rate.

If no faces are detected, and the timer exceeds the SLEEP time setting in process 603, then in process 604, the computer is sent into a SLEEP mode, which may correspond to an ACPI G2(S3) mode.

If faces are detected in process 601, then in process 605, the face detection is algorithm is run in a "double take" false positive detection mode. In the "double take" false positive detection mode, the face detection algorithm accelerates the rate at which frames are analysed, increasing the analysis rate to a higher analysis rate, for example in the range equal to or greater than 10 frames per second, and typically in the range 20 to 40 frames per second.

Operating at a higher rate of frames per second increases the power consumed by the central processing unit, compared to the lower frame analysis rate of 0.5 to 4 frames per second and preferably 0.5 to 2 frames per second, for the duration of which the face detection algorithm operates in that mode. The purpose of running in the "double take" mode is to check that the original face detection which triggered entry into the double take mode was a true face detection, and not just a false face detection. In other words, once the algorithm has made a positive face detection running in a low frame rate mode, it moves to * * a higher frame rate mode to double check whether that face detection is a true face detection, or is a false alarm. The computer does this by moving to a higher S..

S

P2022.spec fame analysis rate, until it is positively confirmed one way or the other whether a face has been positively detected.

If the initial face detection turns out to be a false alarm in process 605, that is, if the double take mode analysis does not confirm the results of the original face detection, then the original face detection is considered to be a spurious false detection and the timer continues previously to count up, without being reset, in process 602.

However, if the face detection algorithm operating in the "double take" mode confirms that a face has been detected in process 605, then in process 606 the computer is activated into an ON state, which may correspond to a GO(s) mode.

When moving into the ON state, the computer comes out of the SLEEP state and is ready for use.

In a modification to the above specific embodiments and methods, a plurality of digital cameras may be used instead of a single camera such that each of the cameras has a field of view covering a position in which a user of the equipment will reside in whilst using the equipment. The images from the cameras may be analysed in multiplexed sequence, or may be analysed substantially in parallel by the processor, and a user may be detected as a result of an OR configuration of the analysed images. That is, if either one camera or another gives a positive user identification, then that positive identification may be selected. Whilst in the relatively slower frame rate mode, images may for S's. example be analysed from two or more cameras in turn, each camera having a * slightly different field of view, thereby increasing the field of view of the detection process. Similarly, in a relatively faster frame rate capture and/ or analysis * "checking" mode, a weighted average of positive user identified images may be selected. As will be appreciated by the person skilled in the art, the images which *S* * contain positive user presence can be selected by and OR function, or by any P2022.spec one of a number of other know algorithms or logic functions, such as an AND function or by an averaging function to check and verify by more than one camera that a user is present in a position ready to use the equipment.

Whilst in the specific embodiments described herein, the specific methods and processes have been described with reference to a computer apparatus, the invention is applicable over a range of electrical apparatus, including but not limited to computer apparatus, domestic and commercial electrical apparatus including for example room lighting, air conditioning, television, audio, audio visual apparatus and the like, and including such types of apparatus installed in vehicles such as automobiles, aircraft and trains.

In other embodiments, the sleep modes and hibernate modes may be generic sleep and hibernate modes and need not correspond to the ACPI standard modes referred to herein. I.. * * * ** S * S.. * . **Se *S*. * S S...

S

S..... * S * .. S * S * .. * *..

P2022.spec

Claims

Claims 1. A method of minimising power consumption of an item of electrical equipment, said method comprising: capturing a succession of digital images; analysing said succession of digital images at a first frame analysis rate to determine if a user of said equipment is present; if a said user is not detected as a result of said digital image analysis at said first frame analysis rate, continuing to monitor said images at said first frame analysis rate; is if a user is detected as a result of said digital image analysis at said first frame analysis rate, capturing a further succession of digital images; analysing said further succession of digital images at a second, relatively higher frame analysis rate to determine if said user is present; and in response to a user being detected as present as a result of said analysis at said second relatively higher frame analysis rate, selecting one of a plurality of possible operational modes of said equipment. *.s. * * *
2. The method as claimed in claim 1, wherein determining if a user of **** said equipment is present comprises detecting a face of said user in said digital **.* image.S

* SS **S * S *
3. The method as claimed in any one of the preceding claims, wherein said first frame analysis rate is in the range 0.5 to
4 frames per second. **e *

P2022.spec 4. The method as claimed in any one of the preceding claims, wherein said second frame analysis rate is equal to or greater than 10 frames per second.
5. The method as claimed in any one of the preceding claims, comprising capturing a said succession if digital images at a first image capture rate; and if it is determined that a user of said equipment is present as a result of said analysis at a first frame analysis rate, then capturing a further succession of images at a second image capture rate; wherein said second image capture rate is higher than said first image capture rate.
6. The method as claimed in any one of the preceding claims, wherein a said power save mode comprises a SLEEP mode according to the Advanced Configuration and Power Interface specification G3 mode.
7. The method as claimed in any one of the preceding claims, wherein said process of analysing said succession of images at a second relatively higher frame analysis rate comprises: *.
S. * * *analysing a sequence of said digital images; for each said digital image determining whether said digital image contains an image of a human face. * ** * * * * .* *** *

P2022.spec 8. The method as claimed in any one of the preceding claims, wherein said step of determining if a user is present at said second frame analysis rate comprises: counting a number of digital images analysed at said second frame rate, within which a face has been identified; comparing said count number with a pre-determined threshold number; and if said counted number exceeds said pre-determined threshold number, then deciding that a user has been detected.
9. The method as claimed in any one of the preceding claims comprising: if said electrical equipment has been in a sleep mode for longer than a predetermined time period, locking said equipment prior to placing said equipment in an hibernate mode.
10. A carrier having thereon a computer program comprising computer implementable instructions for causing a computer to operate according to the method in any one of claims I to 9.
11. A computer program on a carrier and comprising computer executable instructions for causing a computer to carry out the method as S..claimed in any one of claims 1 to 9. * . S...
12. A computer readable medium having a program recorded thereon *::: where the program is to make a computer execute procedure to carry out the method as claimed in any one of claims 1 to 9. *5SS

P2022spec
13. A power management component for managing power usage of an item of electrical equipment, said power management component comprising: a digital camera capable of capturing a succession of digital images; a digital image analyser capable of analysing said digital images to determine if an image of a user is present in said digital images; and signal generator means for generating an activation signal to transition said electrical equipment into one of a plurality of possible predetermined operational modes in response to a signal generated by said digital image analyser; wherein said digital image analyser operable to: analyse a succession of digital images at a first frame analysis rate to determine if an image of a user is present in said captured digital images; and if a user is detected in at least one of said captured digital images, said analyser operates at a second, relatively higher frame analysis rate, to determine whether the image of a user is present in one or more successively collected said digital images.
14. The apparatus as claimed in claim 13, wherein said analyser comprises a face detection component.*... 25 * * ****
15. The apparatus as claimed in claim 13 or 14, wherein said first frame analysis rate is in the range 0.5 to 4 frames per second. * ** ,*
16. The apparatus as claimed in any one of claims 13 to 15, wherein said second frame rate is equal to or greaterthan 10 frames per second. *.SSP2022.spec I'-,
17. The apparatus as claimed in any one of claims 13 to 14, comprising a plurality of digital cameras, wherein said analyser is configured to analyse digital images from each one of said plurality of cameras and to determine whether a user is present from an analysis of images form more than one said camera. * * * ** * * .** * * **** * * *S..... * . * S. * . . * S.S *SP2022.spec