CAMERA

CAMERA also called computer CAMERA, computer eye etc, it is a kind of video input device, widely used in video conference, remote medical treatment and real-time monitoring, etc. Ordinary people can also each other through camera image in network, a voice conversations and communication. Besides, people also could be applied to the current kinds of popular digital imaging, video processing.

classification

Cameras into digital cameras and analog camera two kinds big. Analog video cameras can be produced acquisition device simulation video signal conversion into digital signals, then will be stored in the computer. Analog camera captured video signals must pass a particular video capture card will analog signals are converted into digital mode, and be compressed can convert to the computer application. Digital cameras can directly to capture images, and then through series and parallel or USB interface to the computer. The computer is now on the market basically with digital camera with a digital camera primarily, but also to use new data transmission interface USB digital camera is given priority to, the most visible on the market at present is this product. Besides still a video capture card is used together with the product, but not yet mainstream. Due to the rapid popularization of personal computers, simulation of the camera overall costs higher reason, USB interface transmission speeds of far outclass serial, parallel port speed, so now market hot spots is mainly the USB interface of digital cameras. The following mainly refers to the USB interface of digital cameras.

Structural components

From the camera principle of work can list of the camera main structure and component:

1, LENS

Lens structure, by some pieces of lens composition, the plastic or glass.

2, be

Can be divided into two types:

CCD (device) will bypass

Complementary metal oxide semiconductor (CMOS

3, digital signal processing chip (DSP)

DSP manufacturers more, on the market popular are: VIMICRO (zhongxing micro) 301P/L, SONIX (pine hannstar) 102/120/128, ST (LOGITECH LOGITECH DSP providers), SUNPLUS (from + key development single-chip CIF and VGA, but image quality general), PIXART (original phase) PAC207 single chip CIF, SQ (lean on strong) SQ930C etc.

4, power camera internal need two kinds of working voltage: 3.3 V and 2.5 V, the latest process chip useful to 1.8 V.

Working principle

The working principle of camera roughly include: scenery through A LENS (LENS) generated optical image projected onto A image sensors on the surface, then into electrical signals, after A/D (frequency-field) after converting into digital image signal, and then sent to digital signal processing chip (DSP) in processing, again through the USB interface transmission to computer processing, through the display can see the image.

Technical indexes

1, image Resolution/Resolution (Resolution)

Second-ranking 1280x1024) say again SXGA (1.3 million pixels

Second-ranking 1024x768) is also called designate (80 million pixels

Second-ranking 800x600) say again SVGA (50 million pixels

Second-ranking VGA (640x480) say again 30 million pixels (35 million refers to 648X488)

Second-ranking CIF (352x288) is also called 100,000 pixels

Second-ranking SIF/QVGA (320x240)

Second-ranking QCIF (176x144)

QSIF/QQVGA (itself) 160x120

2, image formats (imageFormat/Colorspace)

RGB24, 420 is at present the two most popular image formats.

RGB24 second-ranking: indicates the R, G, B three colors each 8bit, up performance 256 levels, thereby can reappear dilution 256 * 256 * 256 colors.

One of I420: YUV format itself.

Second-ranking other formats are: RGB565, RGB444, YUV4:52 and etc.

3, automatic white balance adjustment (AWB)

Definition: requirements in different colour temperature environment, as white objects, screen the image should also is white. Color spectrum ingredients, wen said a light color. Colour temperature low said long wave components. When colour temperature changes, the light in three colors (red, green and blue) ratio will change, needs to adjust the proportion of three colors to achieve the balance of color, this is the white balance adjustment of actual.

4, image compression method

JPEG: (jointphotographicexpertgroup) static image compression method. A lossy image compression method. Compression ratio, the greater the image quality is poorer. As the image accuracy requirement is not high storage space is limited, can choose this format. Currently most digital camera use JPEG format.

5, color depth (colour digits)

Reflect on the color of recognizing ability and imaging colour performance ability, is in fact A/D converter quantization precision, it is to point to will signal into how many levels. Common colour digits (bit) said. Color depth is taller, with image color more gorgeous moving. Now in the market cameras have reached 24 bits, some even are 32-bit

6 and image noise

Refers to the image of speckles dry scratching. Performance for image of a fixed colored speckles.

7, perspective

And people's eyes imaging is supplement principle, simply be imaging range.

8, output/input interface

Serial interface (RS232/422) : transmission rate is slow, for 115kbit/s

Parallel interface (PP) : rate can reach 1Mbit/s

Infrared interface (IrDA) : rate is 115kbit/s, general notebook computer has the interface

Universal serial bus USB: plug and play the interface standards, support hot swaps. USB1.1 rate can reach 12Mbit/s, USB2.0 can reach 480Mbit/s

IEEE1394 (firewire) interface (also called ilink) : its transmission rate can reach 100M ~ 400Mbit/s

The choose and buy guide

Judging from the composition of camera decide a camera quality from hardware speaking mainly are: the camera, main control chip and photosensitive chip.

LENS (LENS)

Five layers "complete bo", also calculate currently top the camera lenses. The composition of the lens, the pieces of lens structure composed, generally with plastic lenses lens (the plastic) or glass lenses (glass). Usually camera with lens structure: 1G1P, 1P, system 2P, 1G2P, 2G2P, 4G, etc. Lens, the more cost is higher; Glass lenses than plastic expensive. Therefore a good quality camera should be USES glass lenses, imaging effect is relatively plastic lenses will be good. Now in the market of mostly camera products to reduce cost, general meeting plastic lenses or half plastic half glass lens (i.e., 1P, system 2P, 1G1P, 1G2P, etc.).

Camera lens, the core is the respectively on market now has two kinds of photosensitive components of the lens, one kind is Coupled Device (CCD will Charge couplers), generally, is used to videotape of high-end technology components, application technology mature, imaging effect is better, but the price is relatively more expensive. Another kind is to compare new photographic Complementary Metal Oxide Semiconductor CMOS device (Semiconductor, Complementary Metal Oxide Semiconductor), it is relative to the CCD low prices, low consumption. The earlier CMOS of illuminant more demanding, now in using CMOS for photographic components of products, by using video source automatic gain reinforcement technology, automatic brightness, white balance control technology, the color saturation, contrast, strengthen and gamma correction edge such advanced image control technology, accessible CCD camera effect. Now the high-end camera, such as Logitech, Creative product basic dominated by CCD photographic components, the mainstream product is basic it is CCD and CMOS vie, overall or CCD effect is better, currently CCD components size for more than 1/3 inches or 1/4 inch, in the same resolution, appropriate chooses element size larger as well. Users can the be fond of according to oneself to choose.

Photographic chip

(to be) is comprised of a digital camera's important constituent, according to component different cent

CCD (Coupled Device, will Charge Coupled components) application in photographic photograph of high-end technology components.

CMOS Complementary Metal Oxide Semiconductor (-), metal-oxide Semiconductor components used in lower image quality of products.

At present the size of the CCD components for 1/3 inches or 1/4 inch, in the same resolution, appropriate chooses element size larger as well. CCD is the advantage of high sensitivity, low noise and signal-to-noise ratio. But the production process complex, low consumption and high cost is high.

CMOS advantage is integration high, low power consumption (less than 1/3 of the CCD) and low cost. But noise is bigger, sensitivity is low and high requirements of a source. In the same pixel under the CCD imagery often appear a gender, MingRui degrees are all very good, colour reduction, exposure can guarantee basic accurate. And CMOS product often appear a gender, the colour of general of real reductive ability weak, exposure are not too good.

So we use cameras, especially in using CMOS chip product more should notice when skills:

First, don't use the backlight environment (which CCD with), especially not leads directly to the sun, otherwise "magnifying glass burned ants" tragedy will happen in your camera head. Secondly ambient light and not too weak, otherwise directly affects image quality. To overcome this difficulty, have two kinds of methods, one is to strengthen the surrounding brightness, 2 it is choose requirement minimum illuminance small products, now some cameras have can achieve 5lux.

Finally it is reasonable use lens zoom, not flex that, through the correct adjustment, cameras can also have filming chip functions. At present, the market sales of digital cameras, basic is the CCD CMOS and equal shares. When using CMOS for photographic components of products, by using video source automatic gain reinforcement technology, automatic brightness, white balance control technology, the color saturation, contrast, strengthen and gamma correction edge such advanced image control technology, complete can achieve and CCD camera comparable effect. By market situation and market development situation such as using CCD camera restrictions, and the image sensor manufacturers few, the main reason is using CCD image sensor cost of high impact.

Main control chip

(DSP) zhongxing micro (VIMICRO) 301Plus main control chip, is the core of the best in the camera one of IC

In DSP choice, is based on camera costs, market acceptance for sure. Now DSP manufacturers in design, production DSP technology has gradually mature, in the technical indexes differences is not very big, just a little bit DSP on subtle link and driver to further improve.

Image resolution

Resolution is we often say how many pixels of the camera is the measure of the camera, an important index, some products are one of the box marked 30 million pixels, or 35 million pixels. In practical applications, camera pixel is taller, shooting out of image quality is better, but on the other hand is not pixels, the higher the better, for the same picture, pixels higher product its interpretation of image ability is stronger also, but relatively it recorded data quantity also are much, so for storage equipment request is much higher, thus in the choice of inappropriate, USES the current mainstream product. Due to the camera prices, computer hardware, imaging effect of the factors such as the camera on market now in 30 million pixels this basic grade on sales. There is due in high pixel CMOS imaging effect is not ideal, thus ruling high pixel camera market is still CCD camera. Thing to note: some resolution logo refers to these product use software to achieve the interpolation resolution, although also can properly increasing income image of precision, but compared with hardware resolution or have the certain disparity.

Video capture speed

Video capture ability is one of the function of the concerns of users, many manufacturers have claimed maximum 30 frames per second, but actual ability to capture video when using does not stumble. At present the video cameras captured by software to realize, consequently for computers require very high, namely the CPU processing power is fast enough, secondly, the different requirements of screen capture capabilities are also different. Now cameras captured picture maximum resolution for 640 * 480, in this resolution digital camera under no can reach 30 frames per second effect, thus capture images can produce beating phenomenon. Compare reality is in 320 x 240 resolution to rely on the combination of hardware and software is more likely to achieve standard rate of capture index, so for the video capture speed completely, just a theoretical index. Users should the practical need according to oneself, choosing the appropriate product to achieve the desired effect in addition to the above said these outside, the user when buying still can consider the factors include an additional software, appearance, the sensitivity of the camera lens, whether built-in microphone etc, another Logitech and web sites such as cooperation, users can set online video camera or network broadcast. These after-sale service can also considered.