Types and differences of image acquisition cards

A typical machine vision system consists of the following five blocks: lighting, lens, high-speed camera, image capture card, and vision processor. The frame grabber is just one component of a complete machine vision system, but it plays a very important role. The following picture shows the German Silicon Software AD4 capture card:

The image capture card, also known as the video capture card, can be used to capture digital video information and store it and play it out. Many video capture cards can acquire audio at the same time as capturing video information, so that the audio portion and the video portion are simultaneously saved and synchronized during digitization.

The interface from the video signal source and the image capture card can be divided into: analog capture card and digital capture card. The analog capture card collects the analog video signal into the PC through the AV or S terminal, and converts the analog signal into a digital signal. The video signal source can be from an analog camera, a television signal, an analog video recorder, and the like.

The digital capture card collects the digital video signal into the PC in a digital-to-digital manner. The video signal source mainly comes from DV (Digital Video Camera) and other digital devices.

An important difference between the analog capture card and the digital capture card is that: using the digital capture card, there is no loss of the video signal during the acquisition process, which can guarantee the same effect as the original video source, and the video signal will have a certain degree when using the analog capture card. Loss.

In layman's terms, we can make an analogy: analog acquisition is similar to using a video recorder to flip a video tape. The sub-bands that are transcribed are always not as clear as the master tape. If you use the sub-band to rip, the effect will be worse. Digital acquisition is like using a computer. Just like copying a data file, no matter how many times it is copied, the copied file is exactly the same as the original file, and there is no difference. The two-in-one capture card refers to the digital analog capture card and the AV+DV capture card. Digital input and output, analog interface input (DV/AV/S-video), full interface board.

If the high-speed camera and the industrial computer are the eyes and brain of the machine vision system, then the image acquisition card is the heart of the machine vision system. It must accurately accept the video data of various specifications of the front-end camera, receive the external trigger pulse, and start the exposure and scanning of the camera, playing an important role in the system.