1. **Pixels**:
In the PAL system, a resolution of 752 (H) x 582 (V) equals approximately 440,000 pixels, while 500 (H) x 582 (V) gives about 250,000 pixels. In the NTSC system, 768 (H) x 494 (V) results in around 380,000 pixels, and 510 (H) x 492 (V) is also considered as 250,000 pixels. The term "high resolution" usually refers to 440,000 pixels, while "low resolution" refers to 250,000. These are commonly known as high, middle, or low solutions based on the effective pixel count.
2. **Minimum Illumination**:
This refers to the lowest level of light required for the camera to produce a visible image. In a dark room, you gradually reduce the light until the object becomes indistinct on the screen. The illuminance at that point is called the minimum illumination. It's an important factor when choosing cameras for low-light environments.
3. **Signal-to-Noise Ratio (SNR)**:
Every electronic system generates some noise, even when not in use. The SNR measures the strength of the video signal compared to the noise level. A higher ratio means a clearer image. The formula used is 20log(V2/V1), where V2 is the video signal and V1 is the noise. The result is measured in decibels (dB).
4. **Electronic Shutter**:
The electronic shutter controls how long the CCD sensor captures light. In bright conditions, it shortens the exposure time, and in low light, it extends it. This is different from a mechanical shutter found in traditional cameras. In the PAL system, the electronic shutter speed can range from 1/50 second down to 1/100,000 second. If the shutter speed is too slow, the image may appear washed out, especially in bright sunlight.
5. **Gamma Compensation**:
Gamma compensation adjusts the brightness curve of the image to match the characteristics of CRT displays. Without this, images might look too dark or too bright. The standard gamma value is 0.45, which helps balance the contrast. Some cameras allow users to switch between 0.45 and 1.0, depending on lighting conditions.
6. **Backlight Compensation**:
When a subject is backlit, such as a person facing a bright window, the camera may underexpose the face. Backlight compensation adjusts the exposure specifically for the area of interest, typically the center of the frame, to ensure the subject is properly lit without overexposing the background.
7. **Synchronization System**:
There are three main types: internal, external, and power synchronization. Power synchronization ensures all cameras capture frames at the same time, preventing flickering or misalignment. This is especially important in systems with multiple cameras. In NTSC systems, power synchronization helps prevent color rolling caused by frequency mismatches.
8. **AGC (Automatic Gain Control)**:
AGC automatically adjusts the brightness of the image based on the available light. While it helps in low-light situations, it can sometimes cause overexposure if set too high. Many cameras include a switch to manually adjust AGC levels.
9. **Auto Iris**:
This feature allows the lens to adjust its aperture automatically based on lighting conditions. There are two common types: video-driven and DC-driven. Some budget cameras may omit this feature, making them less suitable for varying lighting conditions.
10. **Video Output**:
Standard video output is 1Vpp (peak-to-peak). However, some manufacturers may increase the signal strength to make the image appear brighter, which can cause issues with recording devices like DVRs.
11. **Power Consumption**:
Most cameras operate at 12VDC and consume between 90-130mA. They can be powered by 12VDC, 24VAC, or 220VAC, with 24VAC often being compatible with 12VDC as well.
Understanding these terms is essential for selecting and configuring surveillance equipment effectively. Whether you're setting up a security system or working with video technology, knowing the basics will help you achieve better performance and reliability.The Plant Lamp Quantum Edition 320W is a cutting-edge lighting solution for plants. With its advanced quantum technology, it provides optimal light spectrum and intensity for plant growth. The lamp emits a total power of 320W, ensuring sufficient brightness for indoor gardening. It is designed to mimic natural sunlight, promoting photosynthesis and enhancing plant development. The Plant Lamp Quantum Edition 320W is a reliable and efficient choice for plant enthusiasts, offering a compact and sleek design that seamlessly integrates into any indoor gardening setup.
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