What do you mean you like collecting?

What does image acquisition mean? I don't know, friends, let's take a look at Bian Xiao's sharing today!

Image collection refers to the collection of images of a group in one place, which is common in graduate image collection, school image collection, hospital image collection and so on.

Real-time image acquisition

Image information is one of the most important information obtained by human beings, and image acquisition is widely used in digital image processing, image recognition and other fields. Real-time image acquisition and processing plays an important role in modern multimedia technology. Real-time image acquisition is the core technology of digital camera, videophone, multimedia IP phone and teleconference products that are common in daily life. The speed and quality of image acquisition directly affect the overall effect of the product.

At present, the traditional image acquisition is to use image acquisition card or graphics card. The analog video signal of CCD(ChargeCoupledDevice) camera is stored by A/D and then sent to computer for processing. This method is widely used and mature in technology, but there are also some problems. First of all, the output of CCD camera has been converted into analog NTSC or PAL system, and it is output in the form of SVideo or mixed video signal, so it is difficult for the sampling points of the acquisition card to correspond to the pixel points of the camera one by one in the output time sequence, which leads to a great loss of digital video image quality and limited image resolution. Secondly, this method has complex hardware circuit and high cost, which is not conducive to popularization and use.

Ordinary image sensor

What are the common image sensors? CCD？ And CMOS (complementary metal oxide semiconductor). At present, CCD still occupies the main position in the market. With the development of CMOS technology, CMOS sensors have also been widely used. The advantages of CCD are high sensitivity, small pixels, low reading noise and large dynamic range, so it occupies a major position in the field of solid-state imaging. Its disadvantage is that the image sensing array and control circuit cannot be integrated on the same chip, and auxiliary circuits such as pulse driving circuit, signal amplification and A/D conversion are needed, which leads to complex system structure and high cost. However, the geometric size of CMOS sensor is smaller, and the resolution gradually approaches the level of CCD. The most important thing is that the manufacturing process of CMOS sensor is compatible with CMOS process. Each pixel sensing unit has its own buffer amplifier, which can easily integrate auxiliary circuits such as AD converter into the chip. Its peripheral circuit is simple, low power consumption and convenient programming. It is easy to control the frame rate, exposure time and image size, which provides a low-cost and high-quality solution for video image acquisition.

Random access memory

In the process of high-speed image acquisition and processing, off-chip random access memory is often needed. Commonly used random access memory mainly includes dynamic memory? Dynamic random access memory and static memory. At present, the mainstream SRAM in the industry? Generally, the memory cell of DRAM consists of six transistors, while the memory cell of DRAM consists of a single transistor and a passive capacitor. So the advantages and disadvantages of both are obvious. SRAM has short access time, high bus utilization rate and relatively low static power consumption, but it occupies a large area of silicon wafer, has a small capacity and is expensive. It is suitable for fields with small storage capacity and high performance requirements. And DRAM? The process of reading and writing access is complicated, the access time is long, the bus utilization rate is low, and the static power consumption is high because the capacitor will always leak and needs to be refreshed regularly. Its advantages are large storage capacity and low price.

The above is what Bian Xiao shared today, and I hope it will help everyone.