1, the camera resolution is a measure of the merits of an important parameter, When referring to the cameras uptake interval with a white and black stripes, the Monitor Xuan eyes will be able to see the maximum number of lines, When more than a few lines of this, the screen can only see an overcast instead of the longer distinguish between white and black lines. Clarity is divided into horizontal resolution and vertical resolution.
2, test methods, a video camera comprehensive test plan, observed using visual images on the monitor center wedge can distinguish between the maximum number of lines or ten clarity center line to distinguish the greatest lines.
3, attention should be tested
(1) to use the image quality good shots, because the lens can affect the final results of the blood test.
(2) shows the use of black-and-white monitor, and a few lines in more than 600 lines, the use of color monitors, Color saturation should Xuanniu transferred to the minimum, to avoid color luminance signal to signal interference.
4, they should pay attention to procurement
(1) the use of Sony, Panasonic cameras do original horizontal contrast, observation cameras in both black and white lines to distinguish when a gap; The original performance indicators true and reliable contrast, can be purchased cameras clarity indicators to arrive at a correct conclusion.
(2) the purchase of SBC, sometimes matching the relatively poor quality of the camera imaging, in addition to testing center resolution, Testing of four of its corner or resolution, must not obscure and deformation, otherwise, to be replaced by better shot.
Second, have the most relevant indicators of low light conditions
1, the lowest illumination of the concept of the camera brightness output level is rated Level (700mv) at the half, Perturbed by the smallest object illumination.
2, test method
10 Gray Test Card
(1) Comparative Law : cameras placed darkroom, choose a plant from the original camera for

Contrast that with the use of two types of manual aperture lenses, dark room with the regulator control of the 220 V incandescent lamp. to regulate voltage regulator to regulate the levels of indoor lights dark shades, and the voltage can be transferred from 0 V 220 V, Indoor illumination can also rise from the dark most observant, two cameras were aimed at rich layers of objects, reduce indoor brightness until the blind to objects of the secret level, or the lens aperture for a small transfer contrast, According to the original manufacturers of cameras nominal value of the low light cameras speculated analyte values the lowest illumination.

(2) Instrument : darkroom in the same test, 10 cameras at the gray test cards, reduce indoor brightness, until the video camera output signal oscilloscope in the spokes degrees to 350 mv. reuse meter measurement test cards surface illumination values calculated lowest illumination.

3, testing should be noted that the lowest illumination of the following four numerical factors.

(1) the aperture lens
(2) the color temperature of light source
(3) video signals in the range
(4) reflectance (target reflectivity and background)

Only four related indicated above, test the low light is the most meaningful, not discard these four simple test conditions and more of a certain brand of camera and illumination nominal value of another brand cameras as degree of nominal value for comparison, otherwise you can not draw any cameras in low light characteristics of a better conclusion.

4, they should pay attention to procurement

Choice of illumination cameras : the nominal low light only for reference. The key is to use occasions according to the need to choose an appropriate camera. Use the meter measuring the scene of the most low light. In the darkroom scene simulation of the light intensity environment, choose different camera test or the use of large diameter aperture of the lens. Gray until a clear distinction between the test card contour 10.

3, the signal-to-noise ratio and the level of intensity of the relationship

1, the so-called "signal-to-noise ratio" refers to the voltage signal to noise ratio of the voltage, the commonly used symbol S / N said. SNR is divided into luminance and chrominance SNR signal-to-noise ratio. SNR is a camera parameters.

When the camera uptake bright scenes, the monitors showed pictures are usually more crisper. Observers screen is not easy to see the interference Hot; When the camera intake of dark scenes, Monitors showed the picture more dark, the observer at this time it is easy to see screen snowflake-shaped interference Hot. Camera higher signal-to-noise ratio, the screen Hot interference effects will become.

2, the luminance signal-to-noise ratio detection method

(1) simple Criterion
Luminance signal-to-noise ratio : lens aperture closed or canceled with the lens cover, the monitors observed snowflake-shaped interference Hot levels.
Chroma signal-to-noise ratio : the camera at the white balance test cards, observed with the color noise points of the position.

(2) Comparative Law

Cameras will be placed in a dark, choose a plant from the original camera for comparison. use the same two models of manual aperture lens and the unknown camera and video camera at the original black balance test cards, using dimmers adjust the size of light until there were obvious on the screen snowflake-shaped interference Hot, Comparing the density of the noise and size, signal-to-noise ratio of the numerical estimates.

(3) Instrument

Luminance signal-to-noise ratio : 10 cameras at the gray test cards, and adjustable aperture size, so that the video camera output level reached 350 mv to access video signal noise measuring device, in the instrument panel directly read SNR readings

3, attention should be tested
¢Ù filter choice, generally use the 100 KHZ fg low and high pass, do not use video weighted curve.
¢Ú to consider cameras AGC and the impact r correction.
4, they should pay attention to procurement

As the video noise measuring instrument is expensive, domestic manufacturers generally do not have this kind of equipment. large manufacturers use oscilloscope signal-to-noise ratio is estimated that the size of small manufacturers visual cameras snowflakes number of points, fill a casual figure, chroma noise measurement is impossible.

Therefore, the purchase of the camera, according to the place of use of illumination conditions degrees choice cameras, the use of measurement and meter record Monitoring use of the venues in different time slots within the illumination value. Top office darkroom simulate the use of the different venues illumination value, which a video camera to observe the noise, increasing the lens aperture or use large diameter optical links of the camera, or increase the use of location lighting brightness until displayed on the monitor image quality to an acceptable level, which is suitable for use in your camera.
4, automatic white balance and color adjustments Reduction
Choi of the Test Card

A color camera reductive color image quality is determined the main factor. People shooting at the white object camera output in red, green, blue three-color signal voltage : VR = VG = VB is called white balance.

Automatic white balance, as the rays of the sun in the morning, at noon, at different times of the color temperature varied widely, artificial light source color temperature are varied, color cameras in different environments color temperature, should also return to the correct white, This requires continuous work of white balance correction at any time.

Color cameras white balance is important parameters, a good CCD can restore the good features color make objects appear clear, natural; When the cameras white balance poor and reproducible images will appear COLOR, in particular will not bring the original color of the features (such as white walls) is also a color.

2, the white balance detection method

(1) visual France

Manual white balance : camera switches on the panel marked 3200 K, 5600K words, cameras showed a white balance adjustment is based on 3,200 K color temperature and color temperature of 5600 K, respectively set.

Use the same color temperature of the artificial light sources (such as fluorescent or Halogen Lamp), camera at the white balance test cards, visualized on the screen whether the observation COLOR.

Auto White Balance : cameras were aimed at two different color temperature of light irradiation tests white balance card, or of the cameras installed 3200 K and 5600 K color temperature change color filter. In COLOR monitors observing the white balance can resume to the original white, observation cameras automatic white balance conversion rate.

(2) Instrument

Cameras will be at the standard color temperature of light source color boxes of test cards, access to the vector signal oscilloscope, Observation showed the six-point fall on whether the vector points. - all through the location and extent of observation video camera out of the red, green, blue, yellow, goods, Green COLOR whether the six colors and color saturation size.

3, testing should pay attention to the problem

Camera white balance performance, the performance of the camera features in the color monitors reduction, which requires a prerequisite, COLOR that can monitor, they would not be able to determine COLOR cameras; Video signal testing the use of optical discs, Monitor output to a white signal to observe whether the white screen COLOR.

4, procurement should pay attention to the problem

Use cameras should be noted that the color temperature of the light source changes COLOR and monitors the right image shows the impact of size, Indeed impact monitoring results, It can adjust the monitor's white balance adjustment circuit or of the cameras installed color temperature adjustment color filter.

Resolution, the low light, white balance and signal-to-noise ratio is the most important camera technology indicators, to be purchased under the four indicators, The price level of integration and comprehensive consideration