Understanding Picture Quality

In the last post on 7th April 2011 we had covered the different technologies available to you and a broad idea of the kind of output you can get from them. At Dee Cee Security Systems Pvt. Ltd. we are committed to suggest you the right technology and the right solution which exceeds your expectations and is within your budget.

Here we will give you a idea of the main aspect of CCTV Cameras which every buyer is looking for but gets confused when he sees technical words like CIF, 4CIF, D1,etc.

Before we go into understanding the above, you need to understand one word which "PIXEL". What is a Pixel?, while you hear megapixel, HDTV and other terminologies nowadays, very few people understand that they are based on amount of pixels they support.

In simple terms, PIXEL stands for Smallest Picture Element. See the below picture:

Image Source: Wikipedia.com

What you see above is a Monitor on the left. On the right side you see a image which is zoomed in version of the image. The selected area is shown as a square on the left side.The element has been red colored and named as Pixel. That is a Pixel. If we name that Pixel as P0 and the next one as P1,P2,P3...... and so..on... then we would get the image resolution. A image resolution bascially refelcts the total number of pixels the image.

Do understand the number of pixels is directly proportional to quality of picture. So higher the number of pixels better the picture clarity.

Following table gives you a idea of the number of pixels expected from a Analog Camera.

Table of Analog Video Resolutions (in pixels)
Format	NTSC-Based (in pixels)	PAL-Based (in pixels)
QCIF	176 × 120	176 × 144
CIF	352 × 240	352 × 288
2CIF	704 x 240	704 x 288
4CIF	704 × 480	704 × 576
D1	720 × 480	720 × 576

To understand the above, i will give you example, QCIF which gives you a resolution of 176 X 144 in PAL( used in Asian Countries) means it will give you a resolution of  176 Pixels X 144 Pixels horizontally and vertically. Thus as we go higher the image size increases.

The following is table of Digital Video Resolution ( or IP Camera Resolution):

Size/ Format	Pixels
QQVGA	160x120
QVGA	320x240
VGA	640x480
HDTV	1280x720
1M	1280x960
1M	1280x1024
2M	1600x1200
HDTV	1920x1080
3M	2048x1536

So you can see the number can go a lot higher in Digital Video Resolution compared to Analog Video Resolution thus offering you Best picture Quality.

You can get in touch with me at rohit at omnipolis.in for any clarifications.

Selection of CCTV Surveillance - Available Technologies

Like i promised in the last post, i would be covering the different technologies available at your disposal in the field of CCTV Surveillance which will help you to make the right choice for your requirement.

There are two technologies which are available to us on the basis of transmission & storage method, quality of picture, which are:

1. Analogue Cameras
2. Digital/IP Cameras

1. Analogue Cameras: Analog Cameras as the name suggests give analog output and the mode of transmission is analog. Analog cameras general come in different resolutions which you mostly hear, such as 420TVL which stands for 420TVLines or 480TVL or 540TVL. As the number of TVL go up the picture resolution or clarity goes up. Transmission of Analog output is done by using RG-59 cable to a Television or a Digital Video Recorder (DVR). DVR converts the signal from analog to digital and records it in a Surveillance Hard Disk installed in the DVR. 95% of the DVR's today are IP-enabled which means the data can be viewed remotely by accessing the DVR. In order to do so the DVR has to connected to internet by providing it a Public Internet Address.

Following is a recorded image of a analog camera having 480TVL resolution:

Image Source: www.globalsecurityllc.com

The above gives you a brief idea on the expected quality of the image from a analog camera.

 2. IP/Digital Camera: Digital Surveillance Cameras are usually referred to as IP Cameras in the security field to avoid general name conflict with Digital Cameras used for taking snaps. IP Cameras as the name suggests give a digital output and digital mode of transmission is required here. Network Cable commonly referred to as Cat-5 or Cat-6 is used here. Digital Output coming from a IP Camera cannot be recorded in a DVR, it can be recorded in a Computer, Server(placed remotely or lcoally) with the help of the Video Management Software provided along with the IP Camera or on Network Video Recorders (NVR) or Hybrid DVR's. Most manufacturers provide free Video Management Softwares for upto 4 IP Cameras while others provide it free for more number of cameras. But as the number of Cameras increase you can keep in mind the cost of Licensing Software as you go along.

A digital "IP camera" with standard resolution (640×480) – (below)

Image Source: www.globalsecurityllc.com

While the difference between the two images is quite visible, IP Cameras offer a advantage in terms of offering better picture quality as the choice can go to Megapixel Cameras when the resolution becomes 2 to 10 times the resolution of the expected resolution from a Analog Camera.

A digital "Megapixel IP camera" with very high resolution (1280×1024) – (below)

Image Source: www.globalsecurityllc.com

While the above gives you a brief knowledge on the technologies and the quality of picture you can expect , do understand that going forward Surveillance Solutions based on IP will gain steam due to the picture clairty, compatibility offered by them it terms of Video Analysis and Real time alerts. The real advantage which Analog offers in comparison to IP is the price. Production of IP Solutions in mass volumes is yet to take place and thus a cost anywhere between 4-5 times more then a similar analog camera at the entry level.

I hope the above helps you in making the right decision in choosing your Surveillance Solution.


@Rohit Jain - Omnipolis