1、BS 8495:2007Code of practice for digital CCTV recording systems for the purpose of image export to be used as evidenceICS 13.310NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDLicensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 22/01/2008 01:46, Uncontrolled
2、Copy, (c) BSIPublishing and copyright informationThe BSI copyright notice displayed in this document indicates when the document was last issued. BSI 2007ISBN 978 0 580 57706 2The following BSI references relate to the work on this standard:Committee reference GW/1/10Draft for comment 07/30156322 DC
3、Publication historyFirst published November 2007Amendments issued since publicationAmd. no. Date Text affectedBS 8495:2007Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 22/01/2008 01:46, Uncontrolled Copy, (c) BSI BSI 2007 iBS 8495:2007ContentsForeword iiIntroduction 11 Scope 12 Normative re
4、ferences 23 Terms, definitions and abbreviations 24 General recommendations 45 Fitness for purpose of recorded images 46 Audit trail 57 Image integrity 68 Time and date integrity 69 Storage 710 Export of images 811 Replay of exported images 9Bibliography 10Summary of pagesThis document comprises a f
5、ront cover, an inside front cover, pages i and ii, pages 1 to 10, an inside back cover and a back cover.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 22/01/2008 01:46, Uncontrolled Copy, (c) BSIBS 8495:2007ii BSI 2007ForewordPublishing informationThis British Standard is published by BSI an
6、d came into effect on 30 November 2007. It was prepared by Subcommittee GW/1/10, Closed circuit television (CCTV), under the authority of Technical Committee GW/1, Electronic security systems. A list of organizations represented on this committee can be obtained on request to its secretary.Use of th
7、is documentAs a code of practice, this British Standard takes the form of guidance and recommendations. It should not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not misleading.Any user claiming compliance with this British Stan
8、dard is expected to be able to justify any course of action that deviates from its recommendations.Presentational conventionsThe provisions in this standard are presented in roman (i.e. upright) type. Its recommendations are expressed in sentences in which the principal auxiliary verb is “should”.Co
9、mmentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element.The word “should” is used to express recommendations of this standard. The word “may” is used in the text to express permissibility, e.g. as an alternative to the p
10、rimary recommendation of the clause. The word “can” is used to express possibility, e.g. a consequence of an action or an event.Notes and commentaries are provided throughout the text of this standard. Notes give references and additional information that are important but do not form part of the re
11、commendations. Commentaries give background information.Contractual and legal considerationsThis publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal
12、obligations.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 22/01/2008 01:46, Uncontrolled Copy, (c) BSI BSI 2007 1BS 8495:2007IntroductionThe demand for this British Standard is based on the change in technology away from the video cassette recorder (VCR) medium. In many cases this has been
13、replaced by digital CCTV recording system (DCRS) technology with the result that specifiers and end users require guidance.The rapid change towards DCRS technology is based on improved reliability, ease of use, ability to search for specific recorded data quickly, no need for daily attention, in par
14、ticular, relating to the constant requirement to change video tapes and the retention thereof. This British Standard does not attempt to establish a preference for the digital recording medium to be adopted but does recommend the areas that should be considered when adopting DCRS technology.The hand
15、ling of evidential digital images within the Criminal Justice System is covered by the Digital Imaging Procedure 1, which states that digital recording technology provides no original that could be produced in evidence. All that is available for use as evidence is a copy of the first, probably tempo
16、rary, recording in memory, and this will be admissible as evidence.Its weight and admissibility as evidence can be influenced by:a) Whether the images audit trail from the digital recording device to the court is robust.b) Whether the integrity of the image can be proven.It is at the courts discreti
17、on whether the evidence is deemed admissible.NOTE 1 Attention is drawn to the requirements of the Data Protection Act 1998 (DPA) 2.NOTE 2 For further information refer to the CCTV Code of Practice published by the Information Commissioners Office 3.1 ScopeThis British Standard gives recommendations
18、for the specification, selection, installation and operation of digital CCTV recording systems (DCRS), for the purpose of generating CCTV images to be used as evidence in a court of law. This document is aimed at assisting specifiers, installers, users, insurance companies, police authorities and pu
19、rchasing organizations. Particular emphasis is placed on the following key areas.a) Fitness for purpose of recorded images.b) Audit trail.c) Image integrity.d) Time and date integrity.e) Storage.f) Export of images.g) Replay of exported images.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 2
20、2/01/2008 01:46, Uncontrolled Copy, (c) BSIBS 8495:20072 BSI 20072 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced documen
21、t (including any amendments) applies.BS 8418, Installation and remote monitoring of detector activated CCTV systems Code of practiceBS EN 50132-7, Alarm systems CCTV surveillance systems for use in security applications Part 7: Application guidelines3 Terms, definitions and abbreviations3.1 Terms an
22、d definitionsFor the purposes of this British Standard, the following terms and definitions apply.3.1.1 audit traildata which allows the reconstruction of a previous activity, in its correct chronological place, or which enables the attributes of a change (such as date/time, operator) to be recorded
23、NOTE The audit trail can be generated by a computer system or manually.3.1.2 authenticationevidence that the original recording has not been altered since first writing to storage medium and that the master copy is an exact copy of the original recorded digital images3.1.3 CCTV cameraunit containing
24、 an imaging device producing a video or digital signal from an optical image3.1.4 CCTV systemsystem consisting of camera equipment, storage, monitoring and associated equipment for transmission and controlling purposes, which might be necessary for the surveillance of a defined area of interest3.1.5
25、 checksumvalue, assigned by an algorithm to an image or metadata, which will change if the data is altered3.1.6 compressionalgorithmic means of reducing the amount of data required to represent video images3.1.7 data encryptionmethod of scrambling the image data in such a way that a reverse algorith
26、m is needed to reconstruct it3.1.8 digital CCTV recording system (DCRS)system that stores images, originating from either analogue or digital capture devices, in digital formatNOTE Examples include DVRs and Network Video Recorders.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 22/01/2008 01:
27、46, Uncontrolled Copy, (c) BSI BSI 2007 3BS 8495:20073.1.9 digital imagerepresentation of a scene as a finite set of digital values 3.1.10 digital watermarkingaddition of verification information to images and associated dataNOTE Visible digital watermarking changes the original image to incorporate
28、 information. If the image file is altered, the watermark is also changed. Invisible watermarking can provide image authentication checks without visibly changing the original image.3.1.11 eventvideo and/or other data recorded on the DCRS that could be of interest3.1.12 event logordered list of even
29、ts that have been recorded on the DCRS, and/or operations that have been applied to the DCRS3.1.13 exact copybit-for-bit replication of digital images3.1.14 exporttransfer and/or copying of data from the original stored location to an alternative storage location3.1.15 fit for purposemeets defined o
30、perational requirements for the recording and replaying of images originating from each individual camera3.1.16 image claritydegree of visibility of relevant information in an imageNOTE Relevant information is that which is defined in BS EN 50132-7 and the HOSDB CCTV operational requirements manual
31、4.3.1.17 master copyexported exact copy made from the original recording and labelled as the master copy3.1.18 metadatadata used as a supplement to other dataNOTE For example, the time and date of when an image is recorded.3.1.19 original recordingfirst instance of digital images recorded to the DCR
32、S 3.1.20 removable hard disk drivehard disk drive designed to be removed without disassembly of the DCRS3.1.21 replayviewing of previously recorded images from the DCRS3.1.22 retention periodlength of time for which digital images are to be held on the DCRS to meet the purpose of the application3.1.
33、23 storagemedia on which digital images are storedNOTE Examples include hard disk drive, tape, CD, DVD, flash memory.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 22/01/2008 01:46, Uncontrolled Copy, (c) BSIBS 8495:20074 BSI 20073.2 AbbreviationsCCTV closed circuit televisionCD compact disc
34、CD-R compact disc recordableDCRS digital CCTV recording systemDVD digital versatile diskDVR digital video recorderRAID redundant array of independent disksSAN storage area networkVCR video cassette recorder4 General recommendationsNOTE 1 Before evaluating the clarity of the recorded images, ensure t
35、hat the purpose of the system is defined in the Operational Requirement; this should state what the customer expects the digital CCTV recording system (DCRS) to do. Factors affecting the clarity of images the DCRS records include:a) subject size within the field of view of the camera;b) lighting of
36、subjects within field of view;c) camera and lens specification;d) transmission medium;e) system maintenance.The installation of the CCTV system should be in accordance with BS EN 50132-7.NOTE 2 The requirements of prEN 50132-1 should also be considered.If appropriate, the installation of the CCTV sy
37、stem should be in accordance with BS 8418.NOTE 3 Attention is drawn to the HOSDB CCTV operational requirements manual 4.NOTE 4 Some CCTV systems are capable of recording audio as well as images. Where this is the case the audio should be correctly synchronized to the images. The audio data should be
38、 treated in the same manner as image data with regard to its integrity.5 Fitness for purpose of recorded imagesThe DCRS should be capable of meeting the Operational Requirement arising from each camera. It should be verified that the DCRS meets the required performance criteria in the following area
39、s:a) Level of recorded digital image compression per camera. NOTE Too much compression will result in loss of detail due to blurring and/or blocking depending on the degree of compression applied. Compression is typically applied to reduce the amount of space required to store the digital images. Le
40、ss compression is better for image clarity.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 22/01/2008 01:46, Uncontrolled Copy, (c) BSI BSI 2007 5BS 8495:2007b) Image per second record rate per camera.NOTE Low image per second record rates might miss certain activity. However, higher image pe
41、r second record rates will require more data to be stored.c) Recorded digital image resolution. NOTE An insufficient resolution setting will result in loss of detail/clarity of received images. Resolution is typically reduced to minimize the amount of space required to store the digital images. High
42、 resolution recording equivalent to the minimum resolution of the capture device is better for image clarity.NOTE Each of these parameters might be adjustable to reflect changes in operating conditions such as differentiation between event/non-event.6Audit trailAs the methods of operation and manage
43、ment of the DCRS can affect the integrity of evidence, actions and events for the DCRS should be logged. The information in an audit trail should be retained for at least 6 months.As a minimum the following events should be logged in the audit trail.a) User logon and logoff.1) ID of the user.2) The
44、time and date of the event.b) Time and date changes (automated and manual).1) System time and date at the point of change.2) New time and date immediately after the point of change.3) ID of user making the change.c) When recording is started or stopped manually.1) Time and date the recording is star
45、ted or stopped.2) ID of user starting or stopping recording.d) Any enhancement applied to images.1) Unique identifier of enhanced image.2) Time and date of image enhancement.3) ID of user enhancing the image.4) Details of enhancement(s).NOTE If multiple enhancements were applied, the order in which
46、they were applied should be logged.e) Exporting of images.1) Unique identifier of exported image.NOTE For example, the time and date the exported image was recorded and the camera label from which it originated.2) Time and date of image export.3) ID of user exporting the image.Licensed Copy: Wang Bi
47、n, ISO/EXCHANGE CHINA STANDARDS, 22/01/2008 01:46, Uncontrolled Copy, (c) BSIBS 8495:20076 BSI 2007f) Images that have been manually tagged or untagged to prevent or permit overwriting.1) Unique identifier of tagged/untagged image.2) ID of user tagging/untagging the image.g) Manual deletion of image
48、s.1) Unique identifier of deleted image.NOTE For example, the time and date the deleted image was recorded and the camera label from which it originated.2) Time and date of image deletion.3) ID of user deleting the image.h) What (if any) removable medium is used for primary storage.NOTE An additiona
49、l audit trail might need to be kept to record the movement and/or storage of removable media to ensure the evidential integrity of stored data.NOTE For further information refer to BIP 0008-1.7 Image integrityThe integrity of images on the DCRS should be maintained by preventing unauthorized access. Protection methods should not prevent images being provided to authorized third parties such as the police.NOTE 1 Control of access to images can be achieved by physical and/or electronic means (e.g. passwords and data encryption). It
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