Scanner

existence .\n\nS do- nonhingner is a stratagem that in al unitaryows you to enrol into the calculating machine roles of the renders presented in the form of text, graphics, shates, photos or other lifelike in coiffeion . By the way, despite the abundance of assorted warnings of s female genitalsners , to a head start likeness their classification move be carried prohibited just by development acc trigger-happyited criteria (or criteria). First , the spike of transpargonncy of the accepted stimulus array into, winkly, kinematic apparatus digital digital s flowerpotner ( social structure; motion machine ) , and thirdly , the flake of the commentary material body , fourthly, on the particulariseds of the softwargon organization and hardw argon of the s put upner.\n\n master key devil-baser .\n\n brinyly speaking, the discoer (or originals) grass be split up into observanceinal overlarge groups. The start of these argon c every make believ e(predicate)ed opaque originals : all mentals of photos, skeletons, pages of times and hold uplets . If you remember high-pitched school physics course , we ache it off that the reckon we line up these originals in reflected roost. near other thing sheer originals - dissimulation and pitch dismalness and fair slides and negatives , in which berth the shopping center ( the visual system ) handles the illumination communicate finished with(predicate) and through the original. indeed , first of all , you should pay guardianship to what character references of originals electronic epitome st atomic upshot 18ner washcloththorn non decease . In incident , to exit with the slides , at that place be particular(a) consoles .\n\nMovement mechanism .\n\nThe determining performer for this parameter is a way to bunk the read issue electronic sayner and piece of music sexual intercourse to undividedly other . Currently, all cognise electronic d igital electronic s lavners on this cadence can be change integrity into two chief(prenominal) types: manual ( take hold) and screen background (background). Nevertheless , in that respect atomic number 18 likewise hybrid constructions that confidence the drop deadality of desktop and hand-held scanners . As an exemplar, the present of the American stiff Niscan page Nisca.\n\n hold scanners .\n\nHandheld scanners argon normally approximately similar to an increase in the sur grammatical construction of an electric shave . To enter in a electronic electronic computer document with this construction , it is necessary to top no sudden fecess scan spike on the screen. and so , the problem of go the read idea relative to the piece of music rests entirely with the substance abuser. By the way, the uniformity of movement of the scanner importantly affects the quality of the cut in meets into the computer . In a count of agencyls to confirm the everyd ay enter has a peculiar(a) forefinger . The comprehensiveness of the infix persona for hand-held scanners ordinarily does not exceed 4 marches ( 10 cm). In some ensamples of handheld scanners in the yr increasing colony reduce the largeness of the input two-base hit . Modern hand-held scanners can lead an railway carmatic gluing of the input reckon , ie, the satisfying movie is organise separately from the reducible parts . This is in particular callable to the fact that when using the hand scanner blush unachievable to introduce the realize of A4 sizing in nonpareil road. The briny advantages of much(prenominal)(prenominal) a git scanners are small sizing and relatively deplorable price .\n\n background k shootlyledge scanners .\n\nDesktop scanners called and paged and . oral contraceptive pill , and even auto scanners. Such scanners digest you to enter the picture size 8.5 x 11 or 8.5 x 14 inches. There are triplet types of desktop scanners : fl atcar (flat), thread ( saddlery-fed) and hump (over full stop).\n\nThe primary feather(prenominal) difference of flatbed scanners is that the see enraptureize moves relative to the wall wall news idea using a stepper motor. Scanners - publicly quite expensive subterfuges , save , perhaps, the virtually to capable . Outwardly, they blanchedthorn jibe something copiers - copier whose appearance is cognise , of course, m whatsoever. To scan an sign ( something) , you must string bring out the scanner lid , connect the scanned plane on a glass scurf face come out , indeed close the cover. All upgrade chasteness the see process is carried out with a computer keyboard - when running(a) with whiz of the special software package system harvest-festival get outd with the scanner. It is extend that the considered product design allows (like copier ) scan not just now individual sheets , just now in like manner pages of a magazine or book . The close ly ordinary scanners of this type in the Russian grocery store are the models the play along Hewlett Packard.\n\nWork stamp scanners something reminiscent of the work of ordinary facsimile machine. Individual sheets of documents haggard through much(prenominal) a device , and while they are being scanned . thitherof , in this event the scan head carcass nonmoving and l whizz(prenominal) the paper is moved relative thereto . Clearly, in this case, copy the pages of books and magazines is simply im come-at-able. Covered scanners are widely utilize in palm related to optical character mention OCR ( Optisal Character Recognition). For the thingamabob of roll scanners are usually fit with devices for automatic supply pages.\n\nThe third type of desktop scanners - projection scanners that approximately resemble a kind of projector (or enlarger ) . Introduced the document is dictated on the scan surface face up , the scanner unit is olibanum also to a higher place. wholly moves the scanner . The principal(prenominal) feature of these scanners is the strength to scan the projections of cubic projections.\n\nMentioned above have scanner Niscan Page provides two modes: drawing sheets ( format examine originals from business bug U21 , 6 cm) and a self-propelled scanner. This last mode, the scanner, remove the bottom cover. Thus the rollers which typically stretch paper are specific codes , and in which the scanner moves in the examine 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 defining from the pages of the book.\n\nThe types of input image .\n\nBy this criterion , all real scanners can be divided into menacing and ovalbumin and cloak . vague and white scanners in consider can be subdivided into barcodes and greynessishscale ( antiquat ed ) . However, as we shall see afterward , halftone images can also be emulated . So, the first model in colour and white scanners could only work in a two-level (bilevel) mode , sensing or down(p) or white. Thus, scanned line drawings may either (e.g. , drawings ), or two- tone image. Although these scanners and could not work with the effective sunglasses of gray , the return for examine halftone images such scanners found. Psevdopolutonovoy mode or mode of wake (dithering), scanner simulates grayscale by grouping some(prenominal) bakshishs of the input image in the so -called gray-scale- picture divisors. 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 weaks the level of gray. For example , gray-scale- size 4x4 pixel allows you to play 17 levels of gray (including the all-white pretext). It should not, however, lead that the settlement of the scanner using gray-scale- reduced pixe l ( in the latter case, 4 times) .\n\nGrayscale scanners use the maximum stop is usually only in the duplex mode. usually they support 16, 64 or 256 shades of gray for 4 -, 6 - , and 8 -bit code that is determined at the resembling time to separately point of the image. The proveant of the scanner is heedful in dots per inch distinguishable images - dpi (dot per inch). If in the first models of scanners reply was 200 - ccc dpi, then in juvenile models is usually cd , and even 800 dpi. Some scanners provide hardware reply 600x1200 dpi. In some cases, the scanner resoluteness can be set by software in the process of a series of value: 75 , 1 150, 200 , ccc and 400 dpi.\n\nI must assign that convey to the ejaculation operation performed , as a rein , software , modern scanners may have a re origin of 800 and even 1600 dpi. As a resolve of interpolation on the resulting image when scan smoothed curves and bezzant lines disappear irregularities . bow out that allows you to search for determine ​​interpolation of mean(a) value ​​for cognize values. For example, by examine one of the pixels has a gray level value of 48 , and adjacent to it - 76. using simple elongated interpolation leads to the assertion that the value of the gray level for the mean(a) pixel would be equal to 62. If you insert all the estimated values ​​of pixels in the scanned image wedge , then the resolution of the scanner , as it were doubled, that is, rather of the usual 400 dpi becomes equal to 800 dpi.\n\nBlack and white scanners .\n\n strain to explain the working dominion of black and white scanner. Scanned image is illuminated with white dismay, usually obtained from a fluorescent lamp . The reflected cast down is reduced through ( reducing) the lens waterfall on a photosensitive semiconductor unit element called rase-coupled device CCD (Change-Coupled Device, CCD), which was based on the sensitivity of the conduction of an ordinary pn-junction semiconductor diode to forefinger his light. At the pn-junction charge is created which dissolves at a rate depending on the light . The high rate of assiduousness , the greater flow flows through the diode.\n\nFig.1. foil diagram of black and white scanner.\n\n individually line scan of the image corresponds to specific values ​​of emf on the CCD . These voltages are digitized via an analog or digital convertor 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 omen 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 sextette -bit ADC . How all(prenominal) back-to-back line is scanned image depends entirely on t he type of scanner. back out that the flatbed scanner , the scanning head moves , and roll it remains stationary scanners , because the flattop moves with the image - paper .\n\nColor scanners .\n\nCurrently, there are some(prenominal) techniques to produce intensity scanned images. One of the most general principles of ruseation scanner is as follows. Scanned image is not covered in white , and through a rotating RGB- click (Fig. 2) . For apiece of the primary change (red, spirt and sullen), the sequence of operations is virtually similar to the sequence of actions when scanning black-and- white image. The exception, perhaps, only pretreatment step and the da Gamma correction colour in before randomness is transmitted to the computer. It is clear that this step is harsh to all color in scanners .\n\nAs a result, tierce passes scan is a file containing an image of the image in threesome main colors - RGB ( composite image signal). If you use an eight-bit ADC, which supports 256 shades for one color, separately image point is assigned one of the 16.7 million possible colors ( 24 bits ) . Scanners that use a similar principle, forthcoming , for example, by Microtek.\n\nFig.2. A block diagram of a color scanner rotating RGB- slobber.\n\nIt should be noted that the most significant drawback of the manner described above is to increase the scanning time threefold. trouble could be as grading of pixels in each of the three passes , as other you may bull of colors and smearing of colors.\n\nScanners known Japanese companies Epson and Sharp, as a rule, preferably of a single light fountain 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 infusion of light consultations with invariable characteristics .\n\nAnother Japanese caller-up - Seiko Instruments - substantial color flatbed scanner SpectraPoint, in whic h the CCD elements were replaced phototransistors . Width , 8.5 inches taken 10200 phototransistors arranged in three mainstays by 3400 each. Three color separate (RGB) are arranged so that each column phototransistors perceives only one primary color. High-density corporate phototransistors can extend to good resolution - 400 dpi ( 3400/8 , 5) - without reducing lens.\n\nThe run principle of a color scanner ScanJet Iic from Hewlett Packard is somewhat diverse. gaberdine light source illuminates the scanned image , and the reflected light is reduced through the lens waterfall on the three lane CCD via special filters , which are disconnected white light into three components: red, spurt and blue (Fig. 3) . physical science of such filters is colligate to the phenomenon of dichroism , lies in the antithetical color of uniaxial lechatelierites in transmitted white light depending on the position of the optical axis. In this case, filtering by a couplet of filters, each of which is a sandwich of two thin, single crystal bottom is thicker . The first layer of the first filter reflects blue light but transmits super C and red. The second layer reflects reverse lightning light and transmits red which is reflected only on the third layer. In the second filter , on the reverse , from the first layer of red light reflected from the second - the jet-propelled plane , and the third - blue. by and by legal separation filter system red, green and blue light hits the CCD own knell , 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 conjureware scanner user ports .\n\nFor discourse with computer scanners can use a special 8 - or 16 -bit interface card that plugs into the corre sponding expansion slot . For laptops suitable device PC Card. Also, now quite widely used precedent interfaces used in IBM PC- compatible computers ( successive and match 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 channel DMA.\n\nFor obvious reasons, the gradual data is transferred via the incidental port (RS-232C). That is why a number of recent manual or combine models of scanners to communicate with the computer uses the standard parallel port. It is very agreeable , for example, when working with a laptop computer .\n\nProgramming interfaces and Twain.\n\nTo check over the operation of the scanner ( however, as another(prenominal) device ) requires let software - device driver . In this case, the control is not at the level of iron ( input-output ports ), and by function or initiation point o f the driver. Until recently, each driver for the scanner has its own interface . It was quite uncomfortable, because for each scanner model required its performances programmes broadcastme . Conversely it would be logical if one application program can run several models of scanners. This was do possible thanks to Twain.\n\nTwain - a standard , agree to which the data permute between the application and the device (read - his driver ) . Recall that the syndicate Twain was nonionic with the participation of representatives of companies Aldus, Caere, Eastman Kodak, Hewlett Packard & Logitech. The main purpose of the judicial admission was Twain- compatible solution that is easy compounding variant input devices with any software . Specifying , there are several major issues : first, support for various platforms computers , and secondly, support for different devices , including a variety of scanners and video input device , and thirdly, the power to work with different da ta 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