Smart IR Camera

As mentioned in “Day and night network cameras” post, in order to see at night or in other situations in which there are low levels of visible light, IR security cameras capture clear images. Such cameras use infrared LED arrays to augment the available ambient lighting.

Sometimes, customers can make the mistake of purchasing an IR camera that does not fit their application because they do not know the size of their coverage area and overexposure is happened. For instance, a person’s face will be “whited out” so that no features can be recognized, making the images captured unusable for identification purposes. This can easily happen for an infrared camera with a 65 foot IR range, but the camera is monitoring an area where people can approach the camera at a much closer distance (5 to 10 feet for example).

Smart IR is a technology was invented to adjusts the intensity of the camera’s infrared LEDs to compensate for overexpose problem. These cameras automatically (combination of hardware and software) adjust the intensity of their built in infrared LEDs to compensate for objects within close distances to the camera lens.

Applications which would greatly benefit from Smart IR include high traffic areas where subjects move towards and away from the camera such as:

• Store fronts
• Gated access points
• Home entry and exit points

Many infrared cameras like VIVOTEK, RedLeaf and Hikvision that are available today include this technology, but not all do, so check your camera’s specification.

Day and Night Network Cameras

Regular, color network cameras are available which delivers color images during the day. But when daylight fades, cameras sense the lower light levels. There are a variety of techniques to improve image quality in condition of poor light.

Camera with IR filter

In this camera, the end user can see picture in total darkness at the distance of infrared emission produced by LEDs. A day and night camera can have infrared LEDs mounted surrounding the lens. These LEDs can emit their own light anywhere from 20 meters all the way up to 70 meters and beyond.

During day time, when the filter is put in place, it filters the wavelengths, improving the quality of the image by showing only the “visible” light, removing the “infrared” light from the spectrum.

When the camera is in night mode (light diminishes below a certain level), the IR-cut filter is removed by a small motor, allowing the camera’s light sensitivity to reach down to 0.001 lux or lower. In this mode, the camera starts recording in black and white.

Remember that a camera’s infrared capabilities are, for the great majority of applications, be used for less than half the day.

Digital day/night cameras

Digital day/night cameras (or electronic day/night cameras) are also available, which electronically adjust colors during the day, instead of using an infrared filter. Once it becomes dark, the camera digitally switches to black and white. Checking the LUX rating is the best way to see how digital day/night cameras are performed.  Without the need for a physical filter, digital day/night technology can also be leveraged for smaller form factors. Day/Night recording is available on dome, fixed dome, bullet, box, and PTZ security cameras.

Almost every IP camera on the market now has some form of day/night feature, from basic image optimization technologies such as the Panasonic BL-C101 and the Sony SNC-CH110, to advanced, day/night functionality in models like the Axis P1347, the RedLeaf RLC-DF2035 and the RedLeaf RLC-BF2422.

Image Scanning Technique

There are two basic ways in which video images can be read or displayed on display screens: interlaced scan and progressive scan.

Interlaced scan

“Interlaced” means the lines that combine the picture on your TV screen are drawn in an alternating method. It means, interlaced video scans the display twice, one contains only the odd lines and other contains only the even lines, to complete a single frame.

The interlaced image rendering method was used in the 1980s, the 1990s saw a growing demand for better resolutions. While this interlaced scanning worked well for older, analog screens, it was not ideal for the new standard of electronic display sets that use a Liquid Crystal Display (LCD).

Analog cameras can use the interlaced scanning technique for transferring images over a coaxial cable and for displaying them on analog screens.

The interlacing technique creates artifacts or distortions as a result of missing data; they are not very important on an interlaced screen. But on larger screens particularly, an irritating flickering effect can sometimes become apparent.

Progressive scan

Progressive scanning is much simpler than interlaced scanning: each line is scanned consecutively until a complete frame is drawn. Computer displays and many recent HD televisions use progressive scanning. While HD was introduced, more and more image creating devices were built with the ability to create superb images applying progressive scanning.

This method of image processing keeps the capture and sending of the complete image together thus producing higher quality and clearer video with sharper motion details and virtually no distortion, zippering, or flickering as they are refreshed at a faster frequency.

 

Megapixel Cameras

Megapixel cameras will bring great changes to the video security business. These cameras can be used in one of two ways: they can enable users to see greater details in a higher resolution image, that would be helpful in identifying people and objects, or they can be used to cover a larger field of view and lower the camera number. These two differences between the VGA and megapixel cameras are determined as follows:

The standard VGA resolution camera supplies a pixel of array of 640×480 that is about 0.3 megapixels. In facial recognition application, VGA cameras could cover a five feet field of view, but a 2 megapixel camera can cover a field of 11 feet and a 3 megapixel camera covers almost 15 feet.

Megapixel cameras use CMOS sensors which require a low operating current. In CMOS cameras, each frame is exposed from top to bottom in a rolling motion. Traditional video uses a series of odd and even lines scanning, called interlacing, to display each video frame, resulting in the blurred or jagged edges of moving objects but each frame in megapixel cameras, eliminate this effect and use progressive scanning.

High resolution cameras transmit greater amounts of data and this additional data takes longer for the camera to process and needs network bandwidth and storage space for recordings, although this can be compensated by using the H.264 video compression standard.

These cameras often deliver low quality images in low light condition, and the automatic gain control used to compensate this situation additional noise. A megapixel compatible lens should be used to ensure that images provide consistently high contrast and high resolution from the center of the lens all the way to the edge. Without using the proper lens, the advantage of the higher resolution camera will be lost in condition that most require megapixel performance.

Right now, the lower frame rates provided by megapixel cameras, but in the future megapixel cameras will offer the same frame rates we’ve expect from standard video.