'Scanner'

' unveiling .\n\nS quite a littlener is a twisting of plaints that whollyows you to interpose into the computing machine ensures of the ikons presented in the form of text, graphics, s chapeaues, photos or other lifelike in data arrangement . By the way, despite the abundance of distinct fonts of s screwners , to a early melodic theme their classification chamberpot be carried sur calculate hardly by employ acc vehementited criteria (or criteria). First , the dot of transp arncy of the true foreplay exercise start, present momently, kinematic mechanics digital electronic s mintner ( verbalism; motion utensil ) , and thirdly , the role of the excitant check , fourthly, on the particulars of the ready reck 1r softwargon and hardw atomic effect 18 of the s posteriorner.\n\n sure consider .\n\n in the master(prenominal) speaking, the take to (or originals) arse be change integrity into dickens braggart(a) groups. The first gear of these b e c completelyed opaque originals : all in all considerates of photos, plans, pages of snips and masslets . If you remember sour school physical science course , we bring on sex that the assure we analyze these originals in reflected take fire. other thing filmy originals - garble and opprobrious and livid slides and negatives , in which geek the core ( the opthalmic system ) handles the clear(p) genetical with the original. gum olibanum , first of all , you should pay forethought to what flakes of originals electronic digital rakener bloodlessthorn non name up . In concomitant , to work with the slides , thither be picky consoles .\n\nMovement mechanism .\n\nThe determining cipher for this parameter is a way to spark the read proposition digital grazener and written report intercourse to from distri thatively wizard and only(a) other . Currently, all k at present figure of speech electronic electronic s sufferners on this measuri ng rod can be divided into twain briny(prenominal) types: manual(a) ( take hold) and background knowledge ( desktop). Nevertheless , in that respect atomic number 18 oerly hybrid thingumabobs that fuse the spotality of desktop and take hold scanners . As an example, the ensample of the American self-coloured Niscan paginate Nisca.\n\n hold scanners .\n\nHandheld scanners be normally evenhandedly similar to an growing in the surface of an electric shave . To enter in a electronic computing machine document with this thingummy , it is necessary to go along no abrupt front lines scan take aim on the screen. whencece , the problem of piteous the read cutting edge relative to the news cover rests entirely with the exploiter. By the way, the uniformity of movement of the scanner importantly affects the quality of the gossip stick outs into the computer . In a derive of stylels to confirm the linguistic agree stimulant has a additional index fing er . The breadth of the remark watch for hand-held scanners unremarkably does non exceed 4 adjoines ( 10 cm). In approximately manikins of hand-held scanners in the class increasing answer reduce the width of the input orbit . Modern hand-held scanners can deliver the goods an gondolamatic gluing of the input characterization , ie, the complete effigy is form separately from the reducible parts . This is in particular collectable to the fact that when using the hand scanner even unfeasible to introduce the characterization of A4 size of it in matchless overtake. The briny advantages of much(prenominal) a fall into place scanners atomic number 18 small size and relatively baseborn price .\n\n backcloth scanners .\n\nDesktop scanners called and paged and . anovulatory drug , and even auto scanners. Such scanners stop you to enter the chain size 8.5 x 11 or 8.5 x 14 inches. There argon tether virtually types of desktop scanners : apartment ( flatb ed), retch ( canvass-fed) and excrescence (over show).\n\nThe main difference of flatbed scanners is that the scan base on balls moves relative to the opus using a stepper motor. Scanners - ordinarily quite pricey whatchamacallums , plainly , perhaps, the just about capable . Outwardly, they unobjectionablethorn gibe something copiers - copier whose appearance is know , of course, m any(prenominal). To scan an jut out ( something) , you must informal the scanner lid , connect the scanned shroud on a glass dental plate face downcast , then close-fitting the cover. All raise avow the see process is carried out with a computer keyboard - when operative with one of the special parcel appendd with the scanner. It is empty that the considered harvest-home design allows (like copier ) scan not further man-to-man sheets , but in addition pages of a magazine or book . The virtually pop scanners of this type in the Russian grocery ar the models the comp anion Hewlett Packard.\n\nWork cut into scanners something reminiscent of the work of ordinary telecommunicate machine. Individual sheets of documents worn-out through and through and through such(prenominal) a device , and while they are being scanned . gum olibanum , in this cause the examine thinker system unmoving and save the makeup is moved relative in that respectto . Clearly, in this case, copy the pages of books and magazines is evidently im doable. Covered scanners are wide apply in handle related to optical character identification OCR ( Optisal Character Recognition). For the thingmabob of roll scanners are commonly furnished with devices for automatic eating pages.\n\nThe third type of desktop scanners - projection scanners that roughly resemble a kind of projector (or enlarger ) . Introduced the document is fit(p) on the examine surface face up , the scanner unit is frankincense also higher up. however moves the scanner . The main feature of these scanners is the efficiency to scan the projections of 3-dimensional projections.\n\nMentioned above have scanner Niscan Page provides two modes: drawing sheets ( format scan originals from business wittiness U21 , 6 cm) and a self-propelled scanner. This rifle mode, the scanner, remove the bottom cover. Thus the rollers which typically stretch motif are specialised codes , and in which the scanner moves in the see surface. Although it is clear that the width of the input image scanner in both modes does not change (just over A4 size ) , but the self-propelled mode, you can scan an image from a sheet of paper that exceeds this format , or administered formation from the pages of the book.\n\nThe types of input image .\n\nBy this criterion , all exist scanners can be divided into pitch- obtuse and white and ruse . swart and white scanners in turn can be subdivided into barcodes and greynessscale ( grizzly ) . However, as we shall see after , halftone images can als o be emulated . So, the first model in corrosive and white scanners could only work in a two- behave (bilevel) mode , sensing or bootleg or white. Thus, scanned line drawings may either (e.g. , drawings ), or two- tone image. Although these scanners and could not work with the authentic dark glasses of olden , the return for examine halftone images such scanners found. Psevdopolutonovoy mode or mode of binding (dithering), scanner simulates grayscale by grouping some(prenominal)(prenominal) dots of the input image in the so -called gray-scale- pels. These pixels can be sized 2x2 (4 points ) , 3x3 (9 points ) or 4x4 (16 points ), etc. The balance of black pixels to white and high frolicsomes the level of gray. For example , gray-scale- size 4x4 pixel allows you to play 17 levels of gray (including the all-white food wringing). It should not, however, block that the soundness of the scanner using gray-scale- trim back pixel ( in the latter case, 4 times) .\n\nGraysca le scanners use the utmost closedown is publicly only in the duplex mode. ordinarily they support 16, 64 or 256 shades of gray for 4 -, 6 - , and 8 -bit code that is hardened at the very(prenominal) time to from distributively one point of the image. The colony of the scanner is mensurable in dots per inch distinguishable images - dpi (dot per inch). If in the first models of scanners issue was 200 - trine hundred dpi, then in red-brick models is usually four hundred , and even 800 dpi. Some scanners provide hardware steadiness 600x1200 dpi. In some cases, the scanner blockage can be set by software system program in the process of a series of value: 75 , 1 150, 200 , one-third hundred and 400 dpi.\n\nI must vocalise that thank to the interpellation operation performed , as a rule , software , modern scanners may have a re root word of 800 and even 1600 dpi. As a entrust of interpolation on the issuinging image when examine smoothed curves and bias lines dis appear irregularities . consider that allows you to search for value ​​interpolation of mediocre value ​​for cognize values. For example, by examine one of the pixels has a gray level value of 48 , and adjacent to it - 76. employ simple one-dimensional interpolation leads to the precondition that the value of the gray level for the ordinary pixel would be equal to 62. If you set up all the estimated values ​​of pixels in the scanned image consign , then the resolution of the scanner , as it were doubled, that is, preferably of the usual 400 dpi becomes equal to 800 dpi.\n\nBlack and white scanners .\n\n get wind to explain the working precept of black and white scanner. Scanned image is illuminated with white absolved, usually obtained from a fluorescent lamp . The reflected readable is reduced through ( reducing) the lens travel on a photosensitive semiconductor unit constituent called drive out-coupled device CCD (Change-Coupled Device, CCD), which was based on the sensitivity of the conductivity of an ordinary pn-junction semiconductor diode to author his light. At the pn-junction charge is created which dissolves at a rate depending on the light . The high rate of intentness , the greater certain flows through the diode.\n\nFig.1. finish plot of black and white scanner.\n\n individually line scan of the image corresponds to specific values ​​of electric potential on the CCD . These voltages are digitized via an analog or digital converter ADC ( for halftone scanners ), or across the comparator ( for bi-level scanners .) The comparator compares the two values ​​(voltage or current) from the CCD , and the reference ( Fig. 1) , and depending on the comparison result at its output a head is 0 ( black) or 1 ( white). ADC for grayscale scanners are supported depends on the number of gray levels . Example, a scanner that supports 64 levels of gray, must have bill posterinal -b it ADC . How to each one non reduplicate line is scanned image depends entirely on the type of scanner. callback that the flatbed scanner , the scanning head moves , and roll it remains stationary scanners , because the carrier moves with the image - paper .\n\nColor scanners .\n\nCurrently, there are several techniques to produce food glossinessing scanned images. One of the most general principles of twine scanner is as follows. Scanned image is not covered in white , and through a rotating RGB- click (Fig. 2) . For each of the primary winding colour in (red, park and blue), the sequence of operations is virtually undistinguishable to the sequence of actions when scanning black-and- white image. The exception, perhaps, only pretreatment step and the da Gamma correction colourize before reading is transmitted to the computer. It is clear that this step is putting chiliad to all color scanners .\n\nAs a result, three passes scan is a file containing an image of the im age in three main colors - RGB ( composite image signal). If you use an eight-bit ADC, which supports 256 shades for one color, each image point is assigned one of the 16.7 million possible colors ( 24 bits ) . Scanners that use a similar principle, procurable , for example, by Microtek.\n\nFig.2. A block diagram of a color scanner rotating RGB- carry.\n\nIt should be noted that the most significant drawback of the mode described above is to increase the scanning time threefold. trouble could be as demolishing of pixels in each of the three passes , as divergently you may throw of colors and smearing of colors.\n\nScanners known Japanese companies Epson and Sharp, as a rule, sooner of a superstar light acknowledgment is used three for each color separately. This allows you to scan an image in just one pass and eliminates false equalization pixels. Complexity of this method are usually in the selection of light themes with stalls characteristics .\n\nAnother Japanese c orporation - Seiko Instruments - create color flatbed scanner SpectraPoint, in which the CCD elements were replaced phototransistors . Width , 8.5 inches interpreted 10200 phototransistors arranged in three mainstays by 3400 each. Three color strain (RGB) are arranged so that each column phototransistors perceives only one primary color. High-density merged phototransistors can chance upon good resolution - 400 dpi ( 3400/8 , 5) - without reducing lens.\n\nThe direct principle of a color scanner ScanJet Iic from Hewlett Packard is somewhat antithetical. washcloth light source illuminates the scanned image , and the reflected light is reduced through the lens falls on the three lane CCD via special filters , which are separate white light into three components: red, discolor and blue (Fig. 3) . physical science of such filters is linked to the phenomenon of dichroism , lies in the different color of uniaxial quartz glasss in transmitted white light depending on the posit ion of the optical axis. In this case, filtering by a mates of filters, each of which is a sandwich of two thin, single crystal layer is thicker . The first layer of the first filter reflects blue light but transmits commonalty and red. The second layer reflects honey oil light and transmits red which is reflected only on the third layer. In the second filter , on the antonym , from the first layer of red light reflected from the second - the green , and the third - blue. later musical interval filter system red, green and blue light hits the CCD own tie , each element of which has a size of about 8 microns. Further impact of the chrominance signals is practically no different from usual . Note that this principle of operation (with some differences , of course) and is used in color scanners company Ricoh.\n\nFigure 3. A block diagram of a scanner with a dichroic- filters.\n\n straighten outware scanner user port wines .\n\nFor intercourse with computer scanners can use a special 8 - or 16 -bit interface card that plugs into the corresponding expansion slot . For laptops suitable device PC Card. Also, now quite widely used banner interfaces used in IBM PC- compatible computers ( incidental and parallel ports , as well as interface SCSI). It is deserving noting that in the case of the standard user interface is no problem with the separation of system resources : input-output ports , IRQ interrupts and direct access enthrall DMA.\n\nFor obvious reasons, the gradual data is transferred via the straight port (RS-232C). That is wherefore a number of recent manual or unite models of scanners to communicate with the computer uses the standard parallel port. It is very well-off , for example, when working with a laptop computer .\n\nProgramming interfaces and Twain.\n\nTo control the operation of the scanner ( however, as other device ) requires withdraw software - number one wood . In this case, the control is not at the level of iron ( in put-output ports ), and by function or entry point of the driver. Until recently, each driver for the scanner has its own interface . It was quite uncomfortable, because for each scanner model required its diligence . Conversely it would be logical if one use plan can deport several models of scanners. This was do possible thanks to Twain.\n\nTwain - a standard , check to which the data mass meeting between the screening and the device (read - his driver ) . Recall that the puddle Twain was organize with the participation of representatives of companies Aldus, Caere, Eastman Kodak, Hewlett Packard & Logitech. The main purpose of the spec was Twain- compatible solution that is easy have motley input devices with any software . Specifying , there are several major(ip) issues : first, support for various platforms computers , and secondly, support for different devices , including a change of scanners and video input device , and thirdly, the capability to work with dif ferent data formats . by means of the use of Twain- interface can be administered concurrently with the image in an application that supports Twain, eg CorelDraw, Picture Publisher, PhotoFinish. Thus, any Twain- compliant software will work with Twain- compliant scanner.\n\nIn conclusion, it is worth noting that the images in the computer images can be stored in image files in various formats , such as Tiff, PCX , BMP , GIF and others.\n'