Image acquisition card Type Published: September 7, 2004, China Visual Network According to the main characteristics of the image capture card, as follows (1) Color image acquisition card and black and white image capture card depending on the camera of the camera, image capture card It is also divided into a color image acquisition card and a black and white image acquisition card. However, the color image capture card can also collect black and white images with grayscale levels. (2) The analog image capture card and the digital image capture card currently extensively applied camera is an analog signal camera, and the image acquisition card used in accordance with this is also an analog image capture card. A / D conversion chip is provided on an analog image capture card that samples the input signal in 4: 2: 2 format, and then quantizes, generally quantifying YUV (i.e., RGB) 8 points, incoming video The signal is converted to a digital image signal. Image capture cards used with digital cameras, can be called digital image capture cards. (3) Surface Scan Image Acquisition Card and Line Scan Image Acquisition Card The Acquisition Card supporting the surface scan camera is a surface scan image capture card, which is generally not supported by wire scanning cameras. The mating line scan camera is used by the line scan image acquisition card. Image capture cards for support line scan cameras often support surface scan cameras. 3.1.1.2 Basic technical parameters of board cards The technical parameters of the image capture card have the following aspects: (1) Image Transmission Format Image Acquisition Card needs to support the output signal format used in the system. Most cameras use RS422 or EIA644 (LVDS) as an output signal format. In digital cameras, several image transmission forms of IEEE1394, USB2.0, and Cameralink have been widely used. (2) Image format (pixel format) Black and white image: Usually, the image grayscale grade can be divided into 256, ie, in 8 bits. When there is more accurate requirements for the image grayscale, 10 bits, 12 bits, etc. can be used. Color image: The color image can be combined by the RGB (YUV) of three colors, depending on the 5-8-8, 10-10-10 formats of its brightness level. (3) The number of transmission channels When the camera takes a high-resolution image at a higher rate, it produces a high output rate, which generally requires multiple signals simultaneously, and the image acquisition card should support multiple input. Under normal circumstances, there is a 1st, 2, 4, 8 input, etc. (4) The largest dot matrix supported by resolution acquisition card reflects its resolution performance. General capture cards can support 768 * 576 o'clock, and performance-effective capture card has the maximum point of 64k * 64K. The maximum number of single frames and single frames can also reflect the resolution performance of the acquisition card. (5) Sampling frequency sampling frequency reflects the speed and ability of the capture card to process the image. When performing high image acquisition, you need to pay attention to whether the sampling frequency of the capture card meets the requirements. The current high-grade acquisition card has a sampling frequency of 65MHz. (6) The transfer rate mainstream image acquisition card is powered by the PCI interface between the main board, which is 132Mb / s.
