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By PURPLELEC | 19 September 2023 | 0 Comments

What is the principle of image capture card

  The function of the image acquisition card is to collect image signals into the computer and save them on the hard disk in the form of data files. It is an indispensable hardware device for image processing. Through it, we can transfer the video signals captured by the camera from the camera tape to the computer, and use relevant video editing software to post-edit the digital video signals. Processing, such as cutting pictures, adding filters, subtitles and sound effects, setting transition effects, adding various video special effects, etc. Finally, the edited video signal is converted into standard VCD, DVD and online popular media formats for easy dissemination.
Image capture card
  Image capture card principle
  Acquisition, the process in which video/images are converted into digital images after sampling and quantization, and then input and stored into frame memory. Since the transmission of image signals requires a high transmission speed, the general transmission interface cannot meet the requirements, so an image capture card is needed.
  The signal obtained from the video source is sent to the video capture card through the video interface. The signal first undergoes analog-to-digital conversion, and then is sent to the digital decoder for decoding. The analog-to-digital converter ADC is actually a video decoder. It can be seen that it decodes and digitizes the video signal from the video source. In addition, different video input decoder chips can be selected using different color spaces.
  Video acquisition is the process of converting the analog signal of the video source into digital information through processing, and storing the digital information on the computer hard drive. This analog-to-digital conversion is performed through the capture chip on the video capture card. Usually during the collection process, digital information is also subjected to a certain form of real-time compression processing.
  When the signal input rate of the image acquisition card is high, the bandwidth issue between the image acquisition card and the image processing system needs to be considered. When using a PC, the theoretical bandwidth peak of the image capture card using the PCI interface is 132MB/S.
  1. The field of view (FOV) or scene is the specific part of the real world that the camera and optical system "see".
  2. The CCD chip converts light energy into electrical energy.
  3. The camera outputs this information to the image capture card in the format of an analog signal.
  4. AD-converter converts analog signals into 8-bit (or multi-bit) digital signals. Each pixel independently expresses light intensity in the form of gray level.
  5. These light intensity values are stored in the matrix data structure of the memory from the matrix of the CCD chip.
  Gray Level - The representation of pixel light intensity information. Gray Level is a quantitative representation method of real-world images. Usually the gray value ranges from blackest to whitest from 0 to 255. When light enters a CCD pixel, if the light intensity reaches the limit of CCD sensing, the pixel will be pure white. Corresponding to the gray value of the pixel in the memory is 255. If no light enters a CCD pixel at all, the pixel is pure black. Corresponding to the gray value of the pixel in the memory is 0.

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