1.image sensor 

it’s ccd (also has C-MOS), Mainly divided into color, black and white, 1 / 3 ", 1 / 4", and the brand.

The main difference lies in the size of the sensitivity, which is the most illumination, 1 / 4 illumination than 1 / 3 poor, the principle is simple: the same number of sensitive points, put in 1 / 4 point is definitely more on every little point, he's affected by light the less, of course, illumination on the poor, the advantage of cheaper, there are smaller, smaller board can do.

2.Pixels

In the PAL system, there are 752 (H) x 582 (V), also known as 440 thousand pixels, and 500 (H) x 582 (V) is the so-called 250,000-pixel, in the NTSC system, there are 768 (H) x 494 (V), also known as 380 thousand pixels, and 510 (H) x 492 (V) is the so-called 250,000-pixel, 44 million-pixel, called the high solution, called the low 250,000 solution, P solution or the solution. pixel is more than talking about "effective pixel.

3.Minimum illumination

The simplest definition: in the darkroom, the camera facing the measured object, and then the lights slowly dimmed until the display is about to see clearly until the measured object, when the amount of light illumination, is the most illumination. Enough ambiguity in bar!, in fact have to consider a few millimeters lens, the amount of light into how much the camera AGC to be turned off, the video signal is reduced to the number of IRE, etc.

1.      S/N ratio

Any circuit as long as the noise power will have a post-hearing, including the components and circuit itself generated, of course, the smaller the noise hearing, the screen will look more clean, we use the video signal with the ratio of noise to hearing, said that the bigger the better, of course, mathematical formulas is 20log (V2/V1), V2 refers to video signals, V1 refers to the size of Noise, the unit is the "dB".

2.      Electroic shutter

In order to image brightness is correct, we need to control the camera into the correct amount of light, it is necessary to adjust the amount of light from the lens into the aperture and the camera shutter to proceed, generally we use the manual lens, the iris control will not move the fixed, and if this time the event to the light we do? is very simple, not in the CCD overexposure before, DSP will quickly put on the CCD signal "sweep" down the bar, which is quickly grasp the strong light, light, when a weak grasp more slowly, grasping a rather on my door with the single-lens reflex camera, "Ka Cha" heard, single-lens reflex camera is a mechanical shutter, we have it is electronic, so they are called "electronic shutter”.

3.      BLC

What is the backlight compensation(BLC), is not in keeping the shutter speed, and, for example, when a video camera installed in the ATM on the front of the street, in the sun, the environment is very bright, so machine is very fast shutter speed, of course, only overexposure is not, then if someone withdrawals, face the camera, due to adopt a comprehensive metering machine is basically affected by our environment as a whole is still very bright, high-speed shutter, the human face of the lack of exposure on the Explicit black, that is, photography mentioned above, the "backlight" is: the back of a strong light, resulting in inadequate exposure of the main black.

Therefore, the problem lies in the overall exposure on that, if we just take one part of the designated side to metering, for example, the middle, then draw surface in the middle of face, then DSP will be measured underexposed, it will slow down the shutter speed, At this time human face on the clear, but because of slow shutter speed, resulting in background (the street) but overexposure and a vast expanse of whiteness.

Therefore, the backlight compensation is based on the specific metering area, adjust the electronic shutter (or auto-iris), such that the exposure metering value within the region to normal, not within the region on whether metering, and metering area by the DSP parameter settings, generally are taken from the middle 1 / 9, or with the bottom 1 / 3 into a convex-shaped.

4.      AGC

IT’s the electronic automatic gain, is the basic functions of the camera, it was to make the screen appear brighter more deliberately high-profile, so that when the illumination is very easy to a vast expanse of whiteness, so it was just on this put forward a switch to high - to be low, come on their own

5.      Power Adaptor