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What are the two kinds of TV systems? How many scan lines are designed for each system? What is the frame-rate? Which countries use these system standards?
NTSC is mainly used in USA and Japan. It requires 525 scan lines in each NTSC image, 30 frames per second, and each frame consists of 2 fields constructed in Interlace mode. PAL is a color signal standard first applied in Europe and later used in other areas, including China. PAL requires 625 scan lines in each image, 25 frames per second, and each frame consists of 2 fields constructed in Interlace mode.
What is TVL?
TVL enables us to clearly identify horizontal and vertical arrays of massive black and white lines. The unit we use is called the TV Line (TVL). The TV Line of surveillance camera modules manufactured by Sunnic can be broadly divided into 330, 480, 520 and 650 TVLs.
What is wide dynamic range (WDR)?
Unlike the human eye, a camera cannot identify the objects in the environment with great bright light contrast. The identifiable range is called the dynamic range. If the dynamic range is small in the camera, only the brighter or darker areas under an environment with drastic contrast can be identified. Wide dynamic range increases the dynamic range of the camera to an extent similar to the identification ability of the human eye.
What is color rolling?
When a surveillance camera is recording at a distance a location illuminated with fluorescent lights or a wall with various types of lighting, the light presented in the image appears in interchanging white and yellow shades. This is so-called color rolling. Color rolling basically does not have a serious effect on image quality and resolution; however, there may be image color changes.
IR-CUTは昼と夜で自動的にOLPFを切り換える機械です。昼はDay タイプのOLPFに切り換え、夜はDay & NightタイプのOLPFに切り換えます。このようなビデオカメラは昼間の時、赤外線の影響がなくて、色を比較的に写実させます。
What are the differences between Day models and Day & Night models?
Infrared ray is generated in environments under sunlight and halogen lamps, which is a love-hate situation for infrared surveillance cameras. During daytime, infrared rays from the sunlight are reflected from objects and then are gathered in the light sensor, which means the DSP is unable to accurately compute accurate colors causing distortion in color presentation. However, infrared rays are required as an auxiliary light source at night. When this happens a filter is used to solve this issue. This filter is called an optical low pass filter (OLPF), and is often adopted in surveillance and digital cameras. Two types of filters are often used for surveillance cameras. One is the Day Model OLPF, and the other is the Day and Night Model OLPF, suitable for use in both day and night scenarios.
What is back light compensation (BLC)?
Under an environment with a strong light source, background objects look dull and are difficult to identify. The back light compensation function brightens background objects to achieve effective identification.
What is automatic white balance (ATW)?
When a surveillance camera is installed in an environment prone to color temperature changes, the automatic white balance function makes adjustments along with changes in color temperature to create the most realistic colors. This means that automatic adjustment preserves realistic images of the white portion and prevents overcast of yellow, blue, or other color tones.
What is AGC?
AGC refers to Automatic Gain Control, which automatically adjusts electronic amplification of video signals to compensate for changes in the brightness rank. It makes it easier for us to see in environments with low brightness.
What is Auto IRIS?
Auto IRIS is a lens that can change aperture automatically. Auto IRIS is a lens that can change aperture automatically. The aperture can increase or decrease when the light changes in the environment.The aperture can increase or decrease when the light changes in the environment.