IP cameras «day-night».
Two modes of image formation — color in sufficient light and monochrome in low light — have long been used in color CCTV cameras. This technology, known as «day-night», allows you to increase the sensitivity of the camera.
Day-night technology
It is known that the sensitivity of a color TV camera is an order of magnitude lower than the sensitivity of a monochrome TV camera, since the «color» CCD matrix has a mosaic color filter applied to the photosensitive elements and worsening the light signal characteristic. Additionally, an IR cutoff filter is installed in front of the «color» matrix, which plays an important role in forming an image with correct color rendition, but also negatively affects the sensitivity of the camera. The «day-night» technology is designed to solve the main drawback of color TV cameras and increase sensitivity.
The day-night technology is based on two methods of increasing sensitivity. The first method is to automatically disable color signal processing when the illumination threshold is reached, which increases sensitivity by 1.5–2 times. The second method uses a physical mechanism that removes (shifts) the IR cutoff filter from the sensor, thereby expanding the spectral sensitivity of the camera in the IR range. In this case, the camera electronics also disables color signal processing. The second method increases sensitivity by 3–5 times depending on the spectral component of the illumination.
A number of manufacturers use only the first method, which is usually referred to as the electronic «day-night» function and is implemented at the software level in the camera processor. Of course, the second method is more expensive, since it requires the use of a mechanism with a drive to shift the IR filter. However, it is more effective, especially when used together with the camera IR illuminators. Abroad, this method is often called true day/night, which can be interpreted as «real day-night mode». In the domestic CCTV market, the term «electronic-mechanical day-night function» has become more widespread, reflecting the nature of the process well.
Thus, if for a conventional color camera the characteristic value of the minimum illumination is 1 lux, then for a camera with an electronic-mechanical «day-night» function in black and white mode, the typical value is 0.3 lux.
Features of IP cameras «day-night»
It should be noted that the sensitivity issue for IP cameras was initially more acute than for analog TV cameras. Image processing — digitization and compression inevitably worsen sensitivity. CMOS matrices (CMOS) with megapixel resolution have a relatively low light signal characteristic, and it is these matrices that are widely used in IP cameras today. As a result, literally all IP camera manufacturers from the very beginning of IP CCTV development began to implement the above-described «day-night» technology in their devices. Of course, taking into account the specifics of IP devices.
This refers to setting the threshold values for automatic switching from the color image mode («day») to the monochrome image mode («night»). In analog cameras, the installer is usually given the option to select only the delay for switching the camera from one mode to another. This is necessary to avoid incorrect camera behavior in situations with unstable lighting (in the morning at sunrise, in the city when illuminated from the roadway, etc.). The choice is made in the camera menu from a limited set of fixed values in seconds. In IP cameras with «day-night» technology, the operating mode is configured remotely via the camera's web interface and can be changed at any time without the need for direct access to the device. In many models, the switching delay value is selected smoothly using an interactive scale. Some manufacturers even allow you to set separate threshold illumination values in lux for the «day» and «night» modes, thereby separating the switching thresholds.
However, despite the wider possibilities of setting the switching mode, IP day-night cameras with megapixel resolution cannot compare in sensitivity with VGA resolution cameras using CCD. The reason, as already noted, is in the technical features of CMOS. And here the only way out may be the combined use of cameras and IR illuminators. Considering the fact that the maximum quantum efficiency of CMOS is in the range of 500-600 nm, it is necessary to use IR illuminators operating in the near IR spectrum, namely 740-840 nm. The use of IR projectors with a light wavelength over 850 nm is ineffective.
Another technology used in IP day-night cameras recently is the mechanism of automatic and manual focusing. Despite the existence of specialized lenses with IR correction, correcting defocusing when the camera switches from day to night mode, the problem is not guaranteed to be solved. Especially if the camera works together with an IR illuminator. The predominance of the IR spectrum with a characteristic long wave shifts the focus point relative to daylight. The focusing mechanism, implemented in a number of modern models of IP cameras with day-night mode, moves the sensor, allowing you to adjust the back focus. The mechanism can be activated automatically when switching from mode to mode or manually through the camera's web interface.
The market for cameras with day-night technology
Despite the apparent simplicity of implementing the «day-night» mode, modern models with this technology and powerful image processing processors successfully compete in sensitivity with black-and-white TV cameras of the past. In fact, not only monochrome, but also classic color cameras have given way to «day-night» models on the market. Today, color TV cameras and IP cameras are being reborn as models with an electronic «day-night» function by updating the firmware (device software). The vast majority of new color camera models appearing on the market already use this technology.
AXIS P3344-VE (Axis Communication)
AXIS P3344-VE Fixed Dome Network Camera delivers 1MP or HDTV 720 p images in compliance with the SMPTE standard for resolution, color and frame rate. Wide dynamic range and day and night capabilities provide clear images in both daylight and low-light conditions.
The camera operates at temperatures from -40 °C to +55 °C, with power supply only from a standard Power over Ethernet (IEEE 802.3af) source.
Remote zoom allows you to optimize the viewing angle in the surveillance zone. Remote focus ensures convenient installation. The camera allows for 24/7 video surveillance.
Multiple video streams in H.264 and Motion JPEG formats can be transmitted simultaneously, either at the maximum frame rate or optimized depending on image quality requirements and bandwidth limitations.
AXIS P3344-VE is a weather- and vandal-proof fixed dome camera ideal for harsh environments.
DinionXF IP Camera, Model NWC-0495-10P (Bosch)
The Bosch DinionXF hybrid camera combines the best features of analog and network cameras to deliver high-quality video for the most demanding CCTV applications.
The camera has a highly sensitive 1/3-inch CCD matrix, a DSP processor with 15-bit analog signal processing. There is also an extended dynamic range function (XF-Dynamic), a mechanically switchable IR filter and a charge accumulation mode. The camera provides three independent streams (4CIF@25ips): two MPEG4/H.264 and one M-JPEG, has the ability to directly record to disk arrays via the iSCSI protocol and an intelligent event analysis (IVA) built into the camera.
IXE20DN – megapixel day-night camera with Sarix (Pelco) technology
The IXE20DN day-night camera with a 2.1 megapixel matrix and two processors has a sensitivity in color mode of 0.50 Lux (1x/33 ms), 0.12 Lux (15x/500 ms), and up to 0.03 Lux (15x/500 ms) in monochrome (at f/1.2; 2850°K; SNR >24 dB). This result is achieved by using Low Light technology.
Experts note natural color rendering and autofocus as a serious advantage of Sarix cameras. In addition to image clarity, the Auto Back Focus function allows the camera to automatically rebuild when changing the IR filter, which is very important for «day-night» models.
The presence of two coprocessors allows loading special applications into the camera. For example, analytics, including an adaptive motion detector, an abandoned object detector, a motion direction sensor, an anti-sabotage system, etc. This allows you to reduce the bitrate by setting up transmission with maximum quality of only the most important information. And this is despite the fact that the bitrate is already low for Pelco cameras. By using H.264 High Profile, the company achieved 2.0 Mbit/sec for SVGA@30 fps and 3.3 Mbit/sec for 1080p@15 fps.
IP camera VN-V26U (JVC)
The VN-V26U model with the day-night function is designed to solve round-the-clock surveillance tasks. The optical block is based on a «» CCD matrix with progressive scanning. The camera can simultaneously transmit two video streams MPEG-4 and M-JPEG at 30 fps with a resolution of 640 x 480 or 320 x 240. The camera supports two-way audio communication due to the presence of a built-in microphone and a connector for audio devices.
2 input and 2 output alarm connectors, as well as a motion detector, ensure optimal operation of the camera in complex video surveillance systems. The camera supports PoE technology and can operate in a temperature range from -10 to +50 degrees.
The VN-V26U is integrated into the Milestone Xprotect software. The camera is also fully compatible with Verint's Nextiva software thanks to its support for the VSIP protocol.
As for domestic software, the camera is fully compatible with the Intellect software packages from ITV and Orion-Video from Bolid. In addition, to create IP systems based on the VN-V26U, you can use the free JVC VN-RS800 software for 32 channels and VR-N900/1600 network video recorders.
IP camera SNC-1300 (Samsung Techwin)
This camera is from a new series of megapixel cameras with a day-night mode.
The SNC-1300 transmits images with a resolution of 1280 x 960 over an IP network.
The camera has exceptionally high sensitivity thanks to the CCD matrix and the sliding IR filter. The minimum illumination for color imaging is 0.5 lux (F1.2, 50% IRE).
The SNC-1300 uses patented MPEG-4/JPEG dual codec technology to achieve clear images and real-time multi-streaming with high compression ratio. The SNC-1300 supports various protocols, two-way audio, and motion detection. The SD card slot allows data storage on the included 2GB card. The SVM-S1 centralized management software bundled with the camera helps users build an effective network management system with convenient visual monitoring options including various events and map images.
IP camera CCMS1315 (Siemens)
The newest megapixel IP camera «day-night» in a standard case CCMS1315 is equipped with a 1/3″ CCD matrix, which, unlike the CMOS matrix, allows you to distinguish an image even on the most starless night. Also, the choice of such a matrix is due to the presence of a mechanical IR filter. To view the video image, in addition to the standard set of functions, the camera has a built-in lens, a slot for CF memory cards, a COM port (for controlling rotary platforms), a standard lens connector and many other functional capabilities.
IP camera V1netIP232SB N (V1 Electronics)
IP camera V1netIP232SB N in a standard case with the «day-night» function is equipped with a Sony WDR (Wide Dynamic Range) CCD matrix, thanks to which it can be used at sites with difficult lighting conditions.
V1netIP232SB N is usually installed in the most critical places for surveillance, requiring a high degree of image detail. The IP camera is capable of generating color/black and white images at illumination up to 0.66 lx/(with TDN) : 0.06 lx. The presence of 3 motion detectors, alarm input/output and PoE makes V1netIP232SB N even more efficient. With the help of free NVR-PRO software, you can record in real time in MPEG4 and MJPEG formats with a resolution of 720×576. V1netIP232SB N is equipped with an RS-485 port for controlling the PTZ device via multiple Pelco D/P protocols, etc. The camera supports TCP/IP, HTTP, SMTP, FTP, PPPoE, etc. network protocols. The operating temperature of V1netIP232SB N is 0-45°.
Smartec STC-IP3975A Day-Night PTZ IP Video Camera with 216x Zoom
The high-speed STC-IP3975A model from Smartec is equipped with a 1/4-inch CCD matrix with WDR Sony EXviewHAD, a switchable IR filter, an 18x zoom lens and a PTZ mechanism with 256 presets, 4 tours and 1 route. It transmits high-quality digital video in MPEG-4 format with a resolution of up to Full D1 and a speed of 25 fps at illumination up to 0.005 lux and provides an additional 12x digital zoom. In addition, the STC-IP3975A has all the necessary image adjustment functions, including autofocus, is equipped with an audio input/output, video motion detector, 8 alarm inputs, 1 output and is powered by an AC source with a voltage of 24 V.
The STC-IP3975A pan/tilt device is capable of rotating the camera unit in manual/automatic mode at a speed of up to 90/400 °/s, and tilting it by 100 ° at a speed of up to 400 °/s with an accuracy of 0.025 °. The IP video camera is supplied with Russified NVR software, which provides configuration of the STC-IP3975A over the network and management of the IP video system, consisting of 32 Smartec IP devices.