IP vs analog cameras - what are the advantages and disadvantages of each?

If you are looking to install a security surveillance system in your home or business, one of the decisions you have to make is whether to go with an IP or analog camera. Deciding on IP versus analog cameras is not necessarily a simple decision as there are advantages and disadvantages to each style of camera. We will explore some of these differences more in-depth so you can determine which option is right for you.

The main difference between the two camera types is the way in which the video signal is delivered. Analog cameras turn the video signal into a format that can be received by a television or other receiver such as a VCR or monitor. An IP-based camera, also known as an IP network camera, digitizes the video signal using a specialized encoder that contains an onboard web server. This allows the IP camera to act as a network device, thus allowing captured video images to be viewed not only through an existing network but also through a web browser that can be accessed through the Internet.

Both analog and IP-based video cameras can transmit signals either wirelessly or through wired connections such as Cat-5 cables. IP-based cameras have the added benefit of being able to use switches, hubs, and routers that allow the Cat-5 network to be expanded to much broader ranges. In order to determine which style camera system is best suited to your needs, let us take a closer look at some of the pros and cons of each style.

1. Pros of analog cameras

Lower cost -- Analog cameras generally cost less to purchase than IP cameras.

Greater flexibility of design -- Analog cameras often come in a larger variety of designs such as mini covert cameras to large PTZ models. If you have unique surveillance needs you may find it easier to find the style of camera you need in an analog model.

Superior compatibility -- It is much easier to mix and match cameras and brands if you use analog versions. This can make it easier if you already have existing camera equipment that you wish to incorporate into your surveillance system.

2. Cons of analog cameras

Lack certain features -- Many of the basic analog cameras often lack some of the more advance features such as digital zoom.

Potential interference problems -- If you are installing a wireless surveillance system, analog systems can have interference problems. More importantly, the resulting signals cannot be encrypted. This can potentially mean that someone else can view the signal. Even when you are running hardwire, it can be easily interfered by any electric device and power wire near by the hardwire path.

Long distance applications are more difficult -- If your surveillance needs encompass a wide area, analog cameras may not be your best choice. Analog cameras generally do not accommodate big distances, and getting them to work over broad ranges can be difficult.

Interlacing -- Analog technology even at (4CIF) has a significant problem with interlacing, causing moving objects to blur. A network camera can progressively scan moving objects more clearly. There are no separate interlaced lines, so this method provides a much clearer image.

3. Pros of IP cameras

Megapixel Resolution -- The analog camera follows the old NTSC/PAl specifications, which corresponds to 0.4 megapixels at 4CIF. The newer IP Network cameras require a higher megapixel range. The higher the resolution of the camera, the more the detailed the coverage of large areas. The camera's higher resolution also enables essential surveillance functions such as tilt, pan, and zoom.

Better wireless reception -- IP cameras have encryption built right into them providing for a more secure network. Interference is also not a problem with IP-based models.

Can utilize existing wiring -- Because IP-based cameras act as their own network device, you can often take advantage of existing network wiring within your home. This can make the installation task much easier.

Power Over Ethernet --Getting power to an analog camera means hurdling a major obstacle and shelling out a major amount of cash. With the IP network camera, you have an IEEE 802.3af standard PoE (Power over Ethernet), which means that your networking devices get its power from an PoE-enabled switch over a standard cable that transmits data and video. The device offers major savings to IP camera users as the standard in place means all models or equipment are compatible with the device. PoE also gives the camera centralized backup power, so they continue to work even with a power failure.

Remote access can be easier -- IP cameras are better suited for remote surveillance needs.

4. Cons of IP cameras

Higher cost -- Because of the additional technology that is built into each camera, the cost is generally higher that analog versions.

Higher bandwidth required -- IP cameras require more bandwidth than analog cameras.

Given the pros and cost of each camera type, the decision really comes down to your specific surveillance needs. With an accurate assessment of your needs, the decision of which camera type to go with will become much easier.

 AVS' MPix13 .vs. IPELA(Sony)

AVS' MPix13 is equipped with same hardware platform as Sony's IPELA

1. 1.3 Megapixel resolution - providing the detail and image quality you need for identification of faces, clothing, vehicles, and analysis of events, without creating prohibitive file sizes.

2. Nessy 2 - Nessy 2' is the 1.3 mega pixel MPEG4/MJPEG dual streaming network chip designed by Sony. AVS MPix13 also has the dual streaming network chip that allows MJPEG files to stored at the onsite server (for the best picture quality) and MPEG4 to be streamed over the internet for offsite storage because the file-size is smaller.

Features that available with the AVS MPix13

1. **Sharper, brighter images thanks to ExwavePRO Technology

All-new CCD designed for security applications...

Designing the image acquisition devices used in cameras and camcorders is an expensive, highly specialised business, so it should come as no surprise that security cameras generally use basically the same CCDs for image acquisition as consumer devices. After all, these CCDs are produced using the latest technologies and in such large numbers that costs are kept relatively low. The downside is that these CCD designs are optimized for very different requirements than those that are required in the security or surveillance industry.

Sony is a world-leader in the design and manufacture of CCD and CMOS imaging devices, which are used in a wide variety of products - and not just those which are branded Sony. At the heart of ExwavePRO technology is an all-new CCD design specifically developed to meet the requirements of security applications. The basic imaging technology, ExwaveHAD, is exceptionally efficient at converting light into images. Until now, however, this technology had only been used with interlaced scanning CCDs - typically designed for use in camcorders where interlacing has the benefit of making it easier to capture fast movement at a relatively high resolution.

Interlacing works by splitting each image frame in half, with the sensor scanning every alternative line per frame. In motion, this technique is very effective and is, of course, the basis of both PAL and NTSC TV. For security applications, however, motion is usually a problem. The details of a person or object in motion become more difficult to make out with an interlaced image - the higher the speed, the greater the difference between the two combined interlaced images and the more visual artifacts and blurry an image will seem.

For this reason, all ExwavePRO CCDs use progressive scan technology - which means every frame of video is captured at full resolution with no interlacing. When trying to read the details of a licence plate on a fast-moving car, progressive scan technology effectively doubles the vertical resolution of the image you're analysing and the practical benefits are obvious.

The below left image was captured with the SNC-DS10 Camera (ExwavePRO) and the right image was captured with a Conventional Camera (Progressive scan CCD with a primary filter) in 0.7 lx Lighting Conditions (actual images).

2. Complementary Color Filter technology

In addition ExwavePRO also uses a new Complementary Color Filter technology which results in approximately twice as much light reaching the CCD. Filtering light by color is essential for a CCD to produce a color image and normally Primary Color Filters (Red, Green, Blue) are used, with each filter only passing a single primary color - so for example, the Red Filter passes red light only.

Where Complementary Color Filters are used, however, each filter passes multiple colors. Cyan passes green and blue; magenta passes red and blue; and yellow passes red and green. As a result, the complementary-color filters pass more light, so that sensitivity is higher. A Complementary Color Filter produces a normal looking video output but the higher luminance signal-to-noise ratio results in an image which can be twice as bright as one produced using a Primary Color Filter.

The diagram below shows the 'Complementary Color Filter' vs. 'Primary Color Filter'. The left hand

image is taking in twice the light of the right hand image.

ExwavePRO technology is a key feature of all of Sony's fourth generation network cameras introduced in 2008, from the high resolution SNC-DS10, SNC-DS60 and SNC-CS20 to the Megapixel resolution cameras SNC-DM110, SNC-DM160 and SNC-CM120.

It's a basic rule of CCD design that if the size of the image capture device is unchanged, then increasing the number of pixels will reduce the size of each pixel and consequently the amount of light each pixel receives is diminished and overall sensitivity reduced. For this reason, buying a conventional Megapixel camera comes with a hidden cost in terms of reduced performance in the lowlight conditions which are often most critical for security applications.

The below diagram illustrates the fact that if two images are the same size, increasing the number of pixels must reduce the photoreceptive area for each individual pixel.

The introduction of ExwavePRO technology, alongside the equally innovative Light Funnel system, means Sony's Megapixel cameras deliver higher resolution imaging performance without hidden penalties.

3. New Light Funnel feature can quadruple CCD sensitivity

Sony's range of megapixel cameras all benefit from a new feature designed to enhance image quality, particularly in low light conditions. In fact, at normal shutter speeds, there's almost a fourfold increase in sensitivity using this new Light Funnel feature.

Sensitivity is important because space is limited on CCD or CMOS imaging surfaces. For example, the imaging surface area of a 1/3" device is only 4.8 x 3.6 mm. As more pixels are populated into this limited space, the sensing area of each pixel becomes smaller, thus the imager becomes less sensitive. All Sony megapixel cameras use ExwavePRO technology (progressive scan and complementary color) to help compensate for this issue.

However, a perennial problem with all monitoring cameras is lowlight and night-time operation. One conventional technique to increase sensitivity would be to switch to a slow shutter speed, providing more time to illuminate each video frame. However, this can cause image blur on moving objects, for example a car's number plate or someone's face may become harder to make out.


The below comparison shows images captured using Light Funnel (left) and Slow Shutter (right).

How it works

The Light Funnel mechanism works by combining two pixels horizontally and vertically to form one larger pixel. By combining four pixels into one, the combined photoreceptive area is four times larger than that of a single pixel. As a result, the sensor converts a greater amount of light energy into more electrons to produce a stronger electrical signal. Although the resolution drops to 640 x 480 (VGA) when this function is activated, the benefit is video that is useable in low light conditions.

This function can be activated automatically in response to surrounding light conditions, or on a pre-specified time schedule, allowing operators to monitor moving objects at dusk without manually changing settings.

The below diagram shows how the Light Funnel function changes a standard CCD pixel layout (left image) to group together blocks of four pixels (right image) and increase light sensitivity.

Both of the images below were taken by a Sony network camera with 0.3 lx Lighting. The Light Funnel is ON in the left image, and OFF in the right image.

Sony Megapixel Cameras deliver results

In real-world applications, for example when monitoring exterior locations such as facility perimeters, parking lots, city streets etc, an ideal camera might be the SNC-DM160 Megapixel Camera. This camera combines the Light Funnel feature with Sony's Day/Night technology to provide highly effective 24/7 monitoring.

See below for a more detailed explanation of Day/Night feature, but in essence in lowlight conditions this switches the camera from color to monochrome mode, increasing daytime sensitivity from 0.8 lux sensitivity to 0.15 lux (approximately 15% of the light from a single candle flame). In both color and monochrome modes, the camera is delivering 1.3 megapixel resolution (1280x960). As lighting conditions worsen further, the Light Funnel mode reduces resolution to 640x480 to almost quadruple brightness.

Image Comparison between Sony Megapixel and Conventional Cameras
(simulated images)

Key:
A: These images are from a Standard Defintion Camera, performing in color and in black and white - as day turns to night.

B: These images are from a Sony Megapixel camera. The first two are 1.3M Color, the next two images are in 1.3M B/W and the last image shows Light Funnel on in ultra low light conditions - image resolution is reduced, but is up to four times more sensitive than the conventional Megapixel camera below.

Ex)AVS' MPix, Sony's IPELA

C: These images are from a conventional Megapixel camera (without Light Funnel). The sequence of images show 1.3M Color fading into night - and the image fading completely.
Ex) Arecont, Mobotix, Avigilion

여기 모델명& 가격 삽입.

D: These images are from a conventional Megapixel camera with Day/Night technoloy. The first two images show 1.3M color, whilst the last three images show 1.3M in black and white.

Ex)Arecont, Mobotix, Avigilion

Progressive scan vs. interlaced video

Today, two different techniques are available to render the video: interlaced scanning and progressive scanning. Which technique is selected will depend on the application and purpose of the video system, and particularly whether the system is required to capture moving objects and to allow viewing of details within a moving image.

1. Interlaced scanning

Interlaced scan-based images use techniques developed for Cathode Ray Tube (CRT)-based TV monitor displays, made up of 576 visible horizontal lines across a standard TV screen. Interlacing divides these into odd and even lines and then alternately refreshes them at 30 frames per second. The slight delay between odd and even line refreshes creates some distortion or 'jaggedness'. This is because only half the lines keeps up with the moving image while the other half waits to be refreshed.

The effects of interlacing can be somewhat compensated for by using de-interlacing. De-interlacing is the process of converting interlaced video into a non-interlaced form, by eliminating some jaggedness from the video for better viewing. This process is also called line doubling. Some network video products, such as Axis video servers, integrate a de-interlace filter which improves image quality in the highest resolution (4CIF). This feature eliminates the motion blur problems caused by the analog video signal from the analog camera.

Interlaced scanning has served the analog camera, television and VHS video world very well for many years, and is still the most suitable for certain applications. However, now that display technology is changing with the advent of Liquid Crystal Display (LCD), Thin Film Transistor (TFT)-based monitors, DVDs and digital cameras, an alternative method of bringing the image to the screen, known as progressive scanning, has been created.

2. Progressive scanning

Progressive scanning, as opposed to interlaced, scans the entire picture line by line every sixteenth of a second. In other words, captured images are not split into separate fields like in interlaced scanning. Computer monitors do not need interlace to show the picture on the screen. It puts them on one line at a time in perfect order i.e. 1, 2, 3, 4, 5, 6, 7 etc. so there is virtually no "flickering" effect. As such, in a surveillance application, it can be critical in viewing detail within a moving image such as a person running away. However, a high quality monitor is required to get the best out of this type of scan.

Example: Capturing moving objects

When a camera captures a moving object, the sharpness of the frozen image will depend on the technology used. Compare these JPEG images, captured by three different cameras using progressive scan, 4CIF interlaced scan and 2CIF respectively.

Please note the following:

• All image systems produce a clear image of the background

• Jagged edges from motion with interlaced scan

• Motion blur caused by the lack of resolution in the 2CIF sample

• Only progressive scan makes it possible to identify the driver

Note: In these examples, the cameras have been using the same lens. The car has been driving at 20 km/h (15 mph) using cruise control.