In the CCTV (closed circuit television) digital video recording industry in South Africa, ‘watermarking’ is a mystical word assuring potential buyers of DVRs that the authenticity of their video images as ‘original’ will be upheld in a court of law. For many a DVR sales person it was an absolute must and secured the sale. Says Cliff Rose, MD of Modular Communications, for the buyer “watermarking was the assurance that he was buying something he did not understand, it was not tangible, never tested, but gave him a warm feeling.”
"In reviewing the specifications of more than 40 DVRs, only two machines, supplied by SESCO, had this 'watermarking' technology. Clearly the use of the word has been employed as a sales feature by many suppliers but rarely reduced to paper or verified," says Rose.
"The word 'watermarking' actually has no place in the CCTV industry, primarily because it does not refer to any standard which ensures the originality of a recorded digital image. Because of this fact and the diverse nature of all the DVRs the courts could not begin to try and verify one maker's watermark, if it existed, over another's. This is why we need to go back to the Law of Evidence when dealing with CCTV video images to 'authenticate' the originality of it as video evidence as well as, and this is important, the time, date and place where the recording was made."
Time, date and place
"Since you need a human to set the time and date (very important, probably more important than the picture itself) you will need an expert witness to testify to the correctness and manner in which such settings were made. If you have more than one DVR then they should be time synchronised or you will need to rely on a human again to carry out this function and again verify that this was done correctly," he says.
"To get around this human problem you need your DVR to synchronise to an NTP time/date service via the Internet and in the case of multiple DVRs one should be a synchronised time server and the others networked to it. Your picture content should also, besides the object, give enough peripheral information to verify the place where such recording took place."
Authenticity of recorded information
Adds Rose, "Once we sort out the time, date and place we have to verify that, let us say, the person's image in the picture has not been changed to implicate him/her at a time and place committing a crime of some sort.
"For example, your VCR/multiplexer is set to record video images in a bank. The time and date is set. You have a bank hold up, once the police arrive, you go and extract the VHS tape from the recorder in front of witnesses and seal such in a bag or envelope with supporting affidavits."
Considering the VCR/multiplexer functioned correctly, there is no doubt that;
1. The video footage recorded to tape has not been tampered with.
2. The video footage is a true recording of the sequence of events that took place in front of the cameras.
3. The VHS tape is the original recording of this event.
Says Rose, "I think verifying the authenticity of a VHS (analog) recording is far simpler than verifying the authenticity of a digital video recording.
Why
1. The VCR itself cannot edit the video recording (simply).
2. The VCR is normally not externally accessible by say LAN or ISDN whereby remote software programs can be used to change the recorded images.
3. The video footage storage device (cassette) can be simply removed and stored in a controlled manner.
"So why go to digital?" asks Rose.
For any number of reasons, including:
1. NTP.time/date synchronisation.
2. Multiple DVR time synchronisation.
3. Excellent picture quality.
4. Originality assured of recorded information by digital encryption methods (for example by means of Kalatgate's certification).
Adds Rose, "On the Dallmeier machines the recorded video footage can only be opened by proprietary application tools which have an approved encryption process. Because of this data protection built into the application tools as well as multilevel password protection the access to recorded video information is restricted."
Other benefits of digital include the simplicity of external viewing, removing the questionability of the human agent as a reliable or unreliable witness in respect of time/date settings and authenticity of the stored information as well as other compounding issues like tape change procedures, accessibility to stored tapes, recording over used tapes, tape deterioration and clogging of heads and so on.
Rose suggests that end-users should be wary of anyone who claims a 'watermark' and any system which can be accessed remotely (LAN, WAN, ISDN etc) and have images changed and resaved within the machine. Similarly, compression formats that do not employ appropriate encryption formats for the coding and decoding of digital video information, including time and date information.
So what have we not considered? According to Rose, there are still a number of legal issues that need to be considered, such as:
1. The UK requirement standard for image size in a picture that needs to be obtained before it can be used as evidence in effectively identifying a person.
2. The resolution or quality of such a picture and its ability to properly convey the content of the picture.
3. The new South African Electronic Communications (ECT) Act which controls the manner in which digital video information is communicated between points.
Adds Rose, "There are other factors which could affect the probative value of video recordings, and these mostly stem from the absence of best practice in the use of CCTV, not from the technology itself." These factors include:
1. Recording a picture from a camera with the widest angle lens possible resulting in images like ants.
2. Recording pictures from cameras that only operate well in the day and produce poor pictures in lower light conditions.
3. Recording monochrome images where colour cameras would further assist in the identification process.
4. Selecting a service provider who has no networking experience that includes fibre-optics and very soon Gigabyte network capabilities.
5. The technical inability or incompetence of your service provider that could invalidate the integrity of your digital video information.
6. Equipment that has not been serviced and cleaned regularly.
As Rose concludes, "Buyer beware. Educate yourself, and ask questions. Digital surveillance, used appropriately and in conjunction with the Law of Evidence when dealing with CCTV video images will certainly help you 'authenticate' the originality of it as video evidence."
For more information contact Cliff Rose, Modular Communications, 083 456 9542, [email protected]
The Kalagate Imagery Bureau
1. For details visit www.kalagate.co.uk.
2. The Kalagate certification for DVRs is issued with the qualifying note stating that it is subject to the correct use of procedural safeguards. So the Kalagate certification is important, as well as the data encryption process as well as the handling of the recorded digital video data information.
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