Sensor type
The technology by which the matrix is made is the photosensitive element of the camera.
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CMOS. Also known as CMOS; both of these entries are abbreviations of the same term, only in different languages (English and Russian). Without going into details, it is worth saying that CMOS matrices are notable for their low cost, compactness, good image processing speed and low power consumption, however, due to the design features, they are prone to the appearance of noise in the image, and therefore somewhat lose CCD in terms of image quality.
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CCD. CCD-type matrices (CCDs) are somewhat more complicated and more expensive than CMOS, but they provide better image quality, including in low light conditions — in particular, due to the low level of noise. This is due both to the low level of heating during operation, and to the uniform light sensitivity of each pixel (whereas in CMOS it can “walk” a little).
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HCCD. A variant of the CCD technology described above, featuring improved sensitivity and even better picture quality in low light.
Video resolution
The resolution of the frame taken by the camera in video mode, in pixels — in other words, the size of the picture in dots horizontally (first digit) and vertically (second digit). It should be taken into account here that in the case of reversing cameras, the recording in pixels describes only the frame on the camera matrix itself; to describe the "picture" coming to the connected screen, the designation in television lines (TVL) is used. This is due to the fact that the video signal is transmitted in an analogue format; See Video Resolution below for more on all of this. Here we note that with the same resolution in TVL and the same viewing angles, a camera with a higher resolution in pixels will produce a clearer, more detailed image. But
HD reversing cameras, and even more so
Full HD units.
Video resolution (TVL)
Although modern electronics are dominated by digital standards, car reversing cameras still use an analogue signal transmission format. This is due to compatibility requirements: such video allows you to use fairly simple screens. And although its quality loses to digital, it is quite enough for most of the tasks facing this class of auto electronics.
An analogue video signal has a size in horizontal and vertical dots. But since the number of vertical dots has a strictly defined number of 625 (in the PAL and NTSC colour system), resolution is usually indicated only by the number of horizontal dots (TV lines).
In fact, this parameter describes the quality of the image that is displayed directly on the screen connected to the camera. There are models with a value of
480,
500,
520,
540,
560 TVL and even
higher resolution in TVL. This is important for models with wide viewing angles (see below). On the other hand, in order to use all the features of a camera with numerous TV lines, a screen corresponding to these features is also required; For more details on compatibility with the screen, see specialized sources.
More features
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Auto exposure. The presence in the camera of the function of automatically adjusting the shooting parameters to the degree of illumination of the scene caught in the frame. Exposure in the classical sense is the amount of light perceived by the photosensitive element of the camera; it can be changed by opening and closing the aperture of the lens, as well as by adjusting the shutter speed of each frame. If the range of these adjustments is not enough, a change in the sensitivity of the matrix can also be used in digital devices. Either way, an underexposed image will look too dark, and an overexposed image will look too bright; both are unsuitable for viewing. However, the process of manually adjusting all the parameters is rather troublesome and obviously inappropriate when driving in a car, especially since the illumination of the picture in the field of view of the lens can change in a matter of seconds. Therefore, most modern cameras have an auto exposure function. Thanks to it, the device itself sets the parameters to the optimal level and changes them when the illumination changes. Note that such automation is not ideal, but in the vast majority of cases it is quite enough for normal visibility on the screen.
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Auto white balance. The camera has an automatic white balance correction function. Despite the name, this balance concerns not only white color, but also the overall color gamut of
...the image coming from the camera. Without going into details, its meaning can be described as follows: each type of lighting (sunlight, overcast day, fluorescent lamps in the garage, street lights, etc.) needs its own white balance settings, otherwise the colors in the image will look unnatural - too warm or too cold. Auto-correction, on the other hand, relieves the user of the need to adjust the white balance manually - the device itself determines the type of lighting and reconfigures. At the same time, given the specifics of the purpose of the rear and front view cameras, this function is rather a pleasant addition than a practically significant point - after all, it is not the colors of visible objects that are usually decisive when maneuvering, but their location in space.
— Parking labels. Possibility of displaying by the camera on the connected screen of parking marks — a special scale which is superimposed on the visible image in a special way. Such a scale plays the role of a rangefinder: the distance to the object visible on the screen can be estimated by the mark near which it is located, this greatly simplifies maneuvering in tight conditions. In addition, in some models, it also helps to evaluate the dimensions of the visible openings in width. True, for an adequate display of parking marks, the camera must be installed quite accurately - at the optimal height from the ground and at a certain angle to the horizontal; in regular models (see "Installation type"), this usually does not cause difficulties, but universal models may require ingenuity and painstaking work. We also note that even with an ideal installation, the accuracy of the parking marks will be far from absolute. However, they can be a very useful addition to a "clean" camera image.
- DVR function. The ability to shoot not only in the mode of broadcasting an image to a multimedia screen, but also to record the situation around the car on an external data drive. The DVR function is implemented in advanced models with a separate data processing unit, the design of which provides a slot for a memory card for storing captured video materials.
- Top view. The top view gives you full control over the situation around the car and makes it easier to maneuver in tight spaces. Also, the top view allows you to better see obstacles in blind spots and improves the safety of reversing parking in tight spaces. This feature is found in surround view systems. The projection of the top view is formed by processing images from cameras dispersed around the perimeter of the vehicle.
- Water protection. The presence in the design of the chamber of protection against moisture ingress. This feature is almost mandatory for outdoor models, as they will inevitably be exposed to rain, snow, spray from wheels, etc. In some cases, the manufacturer even indicates the level of this protection. However, even without it, you can be sure that nothing will happen to the camera even in the rain.
- Remote control. A remote control is included with the camera. Unlike conventional household devices, wired remote controls are most often used in automotive electronics; reversing cameras are no exception. This is due to the fact that the wire in the car is often not only cheaper, but also more convenient than an IR sensor or a radio channel. We also note that this function is usually found in premium models that have additional features - for example, switching the viewing angle.