Whitepaper Axis Guide to Image Usability Comparison of IP- and analog-based surveillance systems
Table of contents 1. Axis Guide to Image Usability 3 2. Image usability challenges and solutions 4 2.1 Both very bright and very dark areas in the same field of view Parking garage entrances, sun-lit foyers of buildings 4 2.2 Need for both an overview and ability to identify details Retail store checkouts, airport passport controls 5 2.3 Need for color video surveillance in almost complete darkness Parking lots, university campuses, construction sites 6 2.4 Need for a vertical video surveillance solution Supermarket aisles, tunnels, fence lines 7 2.5 Need for video surveillance in complete darkness Railways, power plants, prisons, ports and marinas 8 2.6 Need to be able to focus on objects at different distances simultaneously Long-stretched parking lots, storage yards 9
1. Axis Guide to Image Usability The importance of image usability in video surveillance The term image quality is often used to describe the performance of video surveillance cameras. However given there are very specific needs and use cases for video surveillance it is necessary to determine how images will be used and what detail will be required. This aspect is best described by the term image usability. It describes the true performance of video surveillance cameras as relevant for a specific application and environment. Image usability can not be measured in numbers Video surveillance cameras are often marketed highlighting technical specifications such as a certain pixel resolution or lux light sensitivity. While these numbers describe the technical capabilities of individual camera components there are many more aspects to achieving optimal image usability for a specific application and environment these numbers alone simply can not express. Image usability is the sum of several factors Different applications and environments pose very specific challenges to a video surveillance camera. In consequence, there can be no one-fits-all camera model. Image usability is the sum of several factors such as, how well the camera manufacturer has integrated the different components, the image processing power of the built-in chip, zoom, resolution, frame rate, the ability to handle different and changing light conditions and much more. The single most important factor however is the selection of the correct camera model for a given application and environment. Sustained image usability over time An often underestimated aspect with significant long term impact is the need for accurate installation and configuration of a video surveillance camera as only this warrants sustained image usability over time. Equally important is that the camera can sufficiently withstand environmental wear and tear so image usability doesn t deteriorate over time. Identifying the right camera for a specific application and environment The most important question to ask is how images will be used and what detail they will need to deliver. Then this needs to be looked at from the point of view of the possible mounting locations for a camera. Once a mounting location has been identified the specific challenges of this camera position need to be evaluated and a suitable camera needs to be chosen accordingly. 3
2. Image usability challenges and solutions 2.1 Both very bright and very dark areas in the same field of view Parking garage entrances, sun-lit foyers of buildings In a setting with very bright and very dark areas a typical camera would produce an image where objects and people in the bright or dark areas would hardly be visible and could not be properly identified. This challenge is commonly faced when monitoring parking garage entrances or sun-lit foyers of buildings. However it can also play an important role in scenarios where this challenge may not be so easily identified at first thought such as for example when monitoring a corridor in an office building and trying to identify a person standing in front of a bright window on a sunny day. It is therefore important to consider a variety of different scenarios a camera may be subjected to in a particular location. Axis s Wide Dynamic Range dynamic capture (WDR) technology enables cameras to handle complex scenes with high contrasts when sunlight creates both very bright zones as well as very dark shadow areas. With this technology cameras can provide homogeneous images without too dark or too bright zones. This allows for identification of people, vehicles and objects no matter if they are in a very bright or very dark zone of the camera s field of view. Axis Wide Dynamic Range dynamic capture (WDR) technology is based on the latest developments in sensor technology, powerful image processing and Axis competence as the industry leader in building cameras tailored to the unique needs and requirements of the video surveillance market. 4
2.2 Need for both an overview and ability to identify details Retail store checkouts, airport passport controls In many application scenarios there is a need to cover a busy area with an overview and at the same time to be able to identify details once an incident has occurred. This includes for example retail store checkouts, airport passport controls, casino tables or multi-lane roads. The challenge is that until an incident occurs it is unknown which area will need to be looked at in detail. In a retail store checkout scenario it may be necessary to clearly see every item a customer is purchasing. For multi-lane roads the ability to clearly identify vehicle license plates is crucial for law enforcement. HDTV/megapixel cameras offer a wide overview coupled with the ability to identify details. They provide images that are more useful, with more image detail and with wider coverage than standard resolution cameras. In a shopping mall scenario for example, the primary objective of a camera installation may be to watch for the presence of people and to view their movements. However should an incident occur, HD/megapixel cameras offer the required detail to be able to better identify a specific person. Axis HDTV/megapixel cameras feature image sensors capable of capturing images at much higher resolutions than those of standard cameras. This means that under the right circumstances, one Axis HDTV/megapixel camera can provide the same coverage as several conventional cameras while providing the same level of detail. 5
2.3 Need for color video surveillance in almost complete darkness Parking lots, university campuses, construction sites Conventional day and night cameras switch to black and white in darkness. There are however many situations where surveillance video with color is an important factor for effectively identifying people, vehicles and objects. Most of the time it will not possible to equip loading bays, parking lots or university campuses with flood lights and operate them during the entire night. Cameras operating with infra-red or thermal technologies can see in the dark but not in color. Axis Lightfinder technology enables cameras to capture color video even in very low-light conditions. Suitable for both indoor and outdoor use, cameras with Lightfinder technology are the perfect solution whenever color video is required for better identification of people, vehicles and objects. Common lowlight applications include parking lots, schools and campuses, construction sites, perimeters of power plants, water treatment plants and prisons, loading bays as well as railway surveillance. Indoor uses are for example only partially lit storage rooms and factory floors. Lightfinder technology is a combination of Axis expertise in image processing, in-house system-onchip development and selection of the best optical components. Cameras with Axis Lightfinder technology are extremely sensitive to light and can deliver color images in almost complete darkness. 6
2.4 Need for a vertical video surveillance solution Supermarket aisles, tunnels, fence lines Conventional cameras capture images in landscape format. There are however many applications where this horizontal image orientation is less than ideal. When using the regular landscape format for narrow view areas nonetheless, then large parts of the field of view will remain unused. Also multiple cameras would have to cover the same segment of a tunnel, perimeter wall or fence that a camera with vertical orientation could. Cameras with Axis Corridor Format technology allow for effective monitoring of view areas that are more vertical than horizontal in shape such as supermarket isles, hallways, staircases, office corridors, fence lines and tunnels. In these situations, the traditional landscape format is not the optimal solution since it creates video streams where a large part of the field of view specifically the left and right sides of the image is redundant. In turn, this means that the image quality is not maximized because the full area and resolution of the camera s image sensor is not utilized. Axis Corridor Format enables cameras to output a vertically oriented video stream adapted perfectly to the monitored area and providing maximum detail. Axis Corridor Format allows a camera to be mounted sideways. Alternatively only the camera s lens can be rotated by 90 degrees. The image is then rotated back 90 degrees by the internal camera software before output so that no further external processing by video management software is necessary creating a very scalable solution for systems ranging from a single camera to hundreds or even thousands of cameras. 7
2.5 Need for video surveillance in complete darkness Railways, power plants, prisons, ports and marinas Conventional cameras do not function in complete darkness. Yet there are many applications where it is necessary to monitor areas and perimeters in complete darkness. These include railways, loading docks, power plants, prisons, parking lots, industrial sites, school and campus areas as well as ports and marinas. Thermal cameras create images based on the heat that radiates from any object, vehicle or person. This gives the thermal cameras the power to see through complete darkness and makes it for example impossible for persons to hide in shadows or dark corners. Thermal cameras do not, however, deliver images that allow for reliable identification. They best work in complement to other cameras or are used to trigger actions such as switching on flood lights or alerting a patrol guard. Thermal cameras from Axis do not require any additional light sources and can deliver reliable surveillance images even in complete darkness. They operate in the Long Wave Infrared (LWIR) range allowing them to track objects even if as cold as ice. 8
2.6 Need to be able to focus on objects at different distances simultaneously Long-stretched parking lots, storage yards Conventional cameras provide limited capabilities for capturing detailed images for both close and distant objects at the same time. This is however required for a number of installation scenarios such as monitoring long-stretched parking lots, loading ramps, docks or storage yards. Here cameras need to be able to focus simultaneously on both objects close as well as distant. Cameras with Axis P-Iris technology provide an increased depth of field by continuously adjusting the camera lens opening for best focus. As a result detailed images for both close and distant objects can be captured. This means that in a long-stretched parking lot vehicles in the first and last rows can both be clearly identified whereas conventional cameras would struggle to focus on both. Axis P-Iris technology is based on high quality lenses and specialized software installed on the camera itself to continuously and very precisely regulate the lens opening through the use of a stepper motor. This way the optimal lens opening position is maintained at all times enabling an increased depth of field as compared to conventional cameras. 9
56017/EN/R1/1402 About Axis Communications Axis offers intelligent security solutions that enable a smarter, safer world. As the global market leader in network video, Axis is driving the industry by continually launching innovative network products based on an open platform - delivering high value to its customers and carried through a global partner network. Axis has long-term relationships with partners and provides them with knowledge and ground-breaking network products in existing and new markets. Axis has more than 1,600 dedicated employees in more than 40 countries around the world, supported by a network of over 60,000 partners across 179 countries. Founded in 1984, Axis is a Sweden-based company listed on NASDAQ OMX Stockholm under the ticker AXIS. For more information about Axis, please visit our website www.axis.com. 2014 Axis Communications AB. AXIS COMMUNICATIONS, AXIS, ETRAX, ARTPEC and VAPIX are registered trademarks or trademark applications of Axis AB in various jurisdictions. All other company names and products are trademarks or registered trademarks of their respective companies. We reserve the right to introduce modifications without notice.