
Camera (CAMERA), also known as PC camera, computer eye, etc., is a video input device, is widely used in video conferencing, telemedicine and real-time monitoring and so on. Ordinary people can network with each other through the camera to have images, sound of conversation and communication. In addition, people can also be used to present a variety of popular digital image, audio and video processing.
Cameras into digital cameras and analog cameras into two categories. Analog camera video capture device can generate analog video signals into digital signals, and then save it in the computer. Analog cameras to capture the video signal must be.
A particular video capture card to convert analog signals into digital mode, and to be compressed before the computer can be converted to use. Digital cameras can capture images, then string, parallel or USB interface spread computer. Now the camera on the computer market in digital camera-based basic, and digital cameras turned around to use the new data transfer interface, a USB digital camera based on the market today are the most visible product. In addition there is a video capture card used in conjunction with the product, but are not yet mainstream. As the rapid spread of personal computers, analog camera's overall high cost and other reasons, USB interface, transfer rate is much higher than the serial port, parallel port speed, so hot the market is mainly the USB interface digital camera. The following mainly refers to the USB interface digital camera.
Works from the camera the camera can list the main structure and components:
1, Lens (LENS): lens structure, composed by the lens of several pieces, a plastic lens (plastic) or glass lens (glass).
2, the image sensor (SENSOR): can be divided into two categories: CCD (charge couple device): charge-coupled device CMOS (complementary metal oxide semiconductor): complementary metal oxide semiconductor camera
3, digital signal processing chip (DSP): DSP manufacturers more, the market is more popular there: VIMICRO (Vimicro) 301P / L, SONIX (Song Han) 102/120/128, ST (Logitech LOGITECH of DSP provider), SUNPLUS (SUN + focus on developing single-chip CIF and VGA, but the image quality generally), PIXART (original phase) PAC207 single-chip CIF, SQ (SQ) SQ930C and so on.
4, Power: The camera requires two internal operating voltage: 3.3V and 2.5V, the latest chip technology be useful to 1.8V.
Camera works roughly as follows: the scene through the lens (LENS) to generate the optical image projected onto the image sensor surface, and then converted to electrical signals, through the A / D (analog to digital conversion) converted into a digital image signal, and then sent to the digital signal processing chip (DSP) in the processing and then transmitted to the computer through the USB interface in the process, the monitor can see the images.
Camera Specifications:
1, image resolution / resolution (Resolution):
● SXGA (1280x1024), also known as 1.3 million pixels ● XGA (1024x768), also known as 800 000 pixels ● SVGA (800x600), also known as 500 000 pixels ● VGA (640x480), also known as 300 000 pixels (350,000 is 648X488) ● CIF ( 352x288), also known as 10-megapixel ● SIF / QVGA (320x240) ● QCIF (176x144) ● QSIF / QQVGA (160x120)
2, the image format (imageFormat / Colorspace): RGB24, 420 is the most commonly used two kinds of image formats. ● RGB24: that R, G, B three colors of 8bit, 256 shades show up, which can reproduce the 256 * 256 * 256 colors. ● I420: YUV formats. ● Other formats: RGB565, RGB444, YUV4: 2:2 and so on.
3, the automatic white balance adjustment (AWB): Definition: Request a different color temperature environment, according to a white object, the screen image should also white. Color temperature, said spectral composition, light color. Long wave components of the low color temperature and more. When the color temperature changes, light in three primary colors (red, green, blue), the ratio will change, need to adjust the ratio of three primary colors to achieve color balance, white balance adjustment that is practical.
4, image compression: JPEG: (jointphotographicexpertgroup) still image compression. A lossy image compression. The greater the compression ratio, the worse the image quality also. Image accuracy is not required when storage space is limited, you can choose this format. Currently, most digital cameras use the JPEG format.
5, color depth (color-digit): reflects the recognition of color imaging and color performance, is in fact A / D converter quantization precision is defined as the signal is divided into many grades. Commonly used color-digit (bit) said. The higher the color depth, color images obtained by the more colorful and moving. Camera on the market today have reached 24, some even 32-bit
6, the image noise: mean image noise aggravation. Expressed as a fixed image color noise.
7, Perspective: the human eye with the principles of imaging are complementary to each other, it simply is the imaging range.
8, input / output interface: serial interface (RS232/422): slow transfer rate for the 115kbit / s parallel port (PP): speed up to 1Mbit / s infrared port (IrDA): the rate is 115kbit / s, the general notebook This computer has a universal serial bus interface, USB: plug and play interface standard, hot-swappable. USB1.1 speeds up to 12Mbit / s, USB2.0 up to 480Mbit / s IEEE1394 (Firewire) interface (also known as ilink): data rates up to 100M ~ 400Mbit / s
View from the camera decide the composition of the quality of a camera is mainly from the hardware: the lens, the master chip and the light-sensitive chip.
Lens (LENS):
Five "full glass", also considered the current top of the camera lens. The composition of the lens is the lens structure,Several pieces by the lens, generally a plastic lens (plastic) or glass lens (glass). Camera with the lens is usually constructed with: 1P, 2P, 1G1P, 1G2P, 2G2P, 4G, etc. Lens, the more the higher the cost; glass lens expensive than plastic. So a good quality camera lens is glass, plastic lens imaging results will be relatively good. Now most cameras on the market in order to reduce product costs, usually with plastic lens or semi-plastic half-glass lens (ie: 1P, 2P, 1G1P, 1G2P, etc.). The core of the camera lens, now available in the market, there are two light-sensitive components, respectively, the lens, one is the CCD (Charge Coupled Device, CCD), is generally used for photographic camera's high-end technology components and application technology mature, better imaging, but the price is relatively expensive. Another is a relatively new type of photosensitive device CMOS (Complementary Metal Oxide Semiconductor, complementary metal oxide semiconductor), it is low cost relative to the CCD, power consumption. Earlier CMOS high requirements for light, now in the use of CMOS components for the light-sensitive products through the use of the image light automatic gain reinforcement technology, automatic brightness, white balance control, color saturation, contrast, edge enhancement and gamma correction and other advanced image control technology, close to the CCD camera effects. Now high-end camera, such as Logitech, Creative's products are used in the basic CCD sensor components, the mainstream products are basically evenly divided CCD and CMOS, or CCD in general better results, more than the current size of CCD elements 1 / 3 inch or 1 / 4 inch, in the same resolution, should choose a larger size components as well. Users can choose according to their preferences.
Image Sensor:
(SENSOR) is an important component of digital camera components, according to the different components into CCD (Charge Coupled Device, charge-coupled device) camera used in photography in high-end technology components. CMOS (Complementary Metal-Oxide Semiconductor, metal oxide semiconductor) image used in lower quality products. The current size of CCD elements, mostly 1 / 3 inch or 1 / 4 inch, in the same resolution, should choose a larger size components as well. CCD has the advantage of high sensitivity, low noise, large signal to noise ratio. But the complex production process, high cost, high power consumption. CMOS has the advantage of high integration, low power consumption (less than CCD 1 / 3), and low cost. But the noise is relatively large, low sensitivity, high requirements for light. Under the same pixel CCD imaging often permeability, that are very good sharpness, color reproduction and exposure to ensure the basic accuracy. The permeability of CMOS products are often general, color reproduction capabilities of physical weakness, exposure is also not very good. So we use the camera, especially when using CMOS chip products should be more focus on techniques: First, do not use the backlight environment (with this CCD), in particular, not directly to the sun, or "magnifying glass burning ants," the tragedy will occur in your camera head. Second, ambient light not too weak, or directly affect the image quality. There are two ways to overcome this difficulty, the enhancement of the surrounding brightness, and second, the minimum illumination requirements of a small selection of products, some cameras now have up to 5lux. Finally, note that it is reasonable to use the zoom lens, do not underestimate this point, with the right adjustment, the camera also can have a shot chips. Currently, the sales of digital cameras, the CCD and CMOS is basically evenly divided. The use of CMOS components for the light-sensitive products through the use of image light automatic gain reinforcement technology, automatic brightness, white balance control, color saturation, contrast, edge enhancement and gamma correction and other advanced image control technology, can with the CCD camera to achieve comparable results. Subject to market conditions and market development, limitations in the use of CCD image sensor camera manufacturers one of the few, mainly due to the high cost of using CCD image sensor effects.
Controll chips:
(DSP) and Vimicro (VIMICRO) control chip, the camera is the best one in the DSP core IC choice is based on the camera costs, market acceptance to be determined. DSP vendors are now in the design, production of DSP technology has matured, the difference in the technical indicators are not great, but some minor part in the DSP and the driver should be further improved.
Finally, note that it is reasonable to use the zoom lens, do not underestimate this point, with the right adjustment, the camera also can have a shot chips. Currently, the sales of digital cameras, the CCD and CMOS is basically evenly divided. The use of CMOS components for the light-sensitive products through the use of image light automatic gain reinforcement technology, automatic brightness, white balance control, color saturation, contrast, edge enhancement and gamma correction and other advanced image control technology, can with the CCD camera to achieve comparable results. Subject to market conditions and market development, limitations in the use of CCD image sensor camera manufacturers one of the few, mainly due to the high cost of using CCD image sensor effects.
Specification:
Image Sensor: □ 35 million □ 130 million □ 200 million
Resolution: 1280 x 960 . 800 x 600 . 640 x 480 . 320 x 240.
Video format: 24 bit true color
Brightness: Auto / manual control
White Balance: Auto / manual control
Lens focal length: 5 cm to infinity
Frame rate: 30 frames / sec.
SNR: 48dB
Microphone Input: □ Yes □ No
Interface: USB 1.1/2.0 compatible interface to
Angle: 58 degrees
System requirements:Win98/Me/2000/XP/VISTA/WIN7
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