Document scanner is considered the perfect tool for digitizing documents, slides, photos and other materials. A document scanner is available in different models depending upon the purpose they are going to be used for. This usually depends on whether the user wants it for business or home applications. There are several types of document scanners that work in different ways; some of them are listed below. Therefore, you should also read this article Top 11 Document Scanners In India | Available At Great Price
This versatile document scanner works like copy machines. They can scan material from thick or thin objects like single sheets of paper, thick books, magazines, flowers as well as jewellery.
Flatbed type of document scanner is the most common desktop scanners. They also look and work a lot like small photocopiers. The target piece of paper or object to be scanned is placed on top of a panel of glass and the light emitted from under the glass reflects off the objects and is captured by the image sensor in the moving scan head. Flatbed scanners gained popularity for their easy-to-use designs and extreme versatility—they can scan photos, books, documents and even three-dimensional objects (depending on the scanner).
Most flatbed document scanners require a transparency adapter (TPA or TPU) to scan slides, film, x-rays and other transparent originals. The transparency adapter is basically a backlight attached in place of the scanner cover.
In addition, if you are not willing to place each page on the scanner individually, an automatic document feeder (ADF) can be used for high-volume scanning (depending on the scanner).
A sheetfed scanner is in many ways similar to a fax machine. This document scanner is ideal for those users who want to scan many documents at the same time. There are various types of sheetfed scanners available that vary depending upon their speed, quality and performance.
Unlike flatbed scanners, sheetfed scanners operate more like fax machines/printers than photocopiers. This document scanner work by moving documents/sheets instead of a scan head. Featuring a built-in ADF (automatic document feeder), the sheetfed scanner is capable of unsupervised scanning. Their compact designs also make them perfect in cramped/limited working spaces.
As it is difficult to move a sheet of paper without introducing distortions, sheetfed scanners tend to be less exact than flatbed units. Therefore, sheetfed scanners are excellent for high-volume scanning (to produce editable/searchable text), but not for high-quality photo scanning. Another important concern about sheetfed scanners is they can only scan loose and individual sheets but cannot handle bound documents/photographs or books directly.
Handheld scanners can be easily held in place on a portable stand. They are mostly used as barcode readers.
Handheld and portable scanners are extremely compact and portable designs that can fit perfectly into a briefcase or travelling bag. They are excellent additions to your laptop and are conveniently shared. Some portable scanners are specifically designed for business card scanning and may be of great help for businessmen and women.
Portable scanners are bigger than handheld scanners but smaller than the traditional flatbed scanners. They are perfect for those who need to scan documents while travelling on business.
Photo scanners have high-resolution image processors that are capable of scanning photo negatives and producing high-quality photo enlargements. There are many types of this kind of document scanners available in the market. Some of them include Canon CanoScan, HP Scanjet and Epson Perfection.
FEATURES OF PHOTO SCANNER
When planning to buy a photo scanner, it is necessary to ensure that the device has the features they require. Now, this kind of document scanner is going to be useful ahead as well hence let’s check out some of the features that are offered by a photo scanner.
Scanner image sensors determine the quality of scans. They convert the light reflected from the object being scanned into a clear digital image. There are three basic types of image sensor: charged-coupled device, contact image sensor, and photomultiplier tubes.
SCANNER BIT DEPTH
Scanners gather a certain number of bits from every pixel of an image. This is called ‘bit depth’ and determines the image quality provided by the scanner.
Scanner resolution is measured in dots per inch (dpi) or pixels per inch (ppi). The resolution of the scanner determines the image quality shown on the resultant copy.
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This feature is mostly seen on document scanners that scan both the sides of the page at the same time. This scanner is often very costly so users can instead opt for a scanner with an automatic document feeder and duplexing capabilities.
HIGHER CONNECTIVITY SPEEDS
Nowadays, most scanners come with USB 2.0 or higher. This feature allows users to scan documents faster with speedy connection to the PC. There are also some scanners that offer USB 3.0 interface for quicker speeds to scan documents.
IMAGE FILE FORMATS
Most scanners are capable of storing scanned images in multiple digital image file formats. These include JPG, PNG, TIFF and BMP files. Some also provide the capability to read and convert files into TXT, PDF or RTF formats.
When buying a photo scanner, it is necessary to be aware of the technical terms that are related to it. Let’s check out some of the important terms that are used in scanners.
Picks up the reflected light from the original image and converts it into digital information.
Scanner Bit Depth:
Defines the number of bits from each pixel of an image. The bit depth determines the quality of the image.
Optical resolution is measured by dots per inch (dpi) or pixels per inch (ppi). Scanners with higher resolution give better image quality with impressive image detail.
Allows users to scan both the sides of the page at the same time.
Image File Formats:
Capable of storing several file formats. The most common file formats are JPG, TIFF, PNG and BMP files.
What are the kind of specifications you should look in a document scanner?
Scanners for electronically forming an image of an original are known. Typically, the captured image provided by a scanner is a pixel data array that is stored in memory in a digital format.
A distortion-free image requires a faithful mapping of the original image to the pixel data array. Scanners typically include at least one means for imposing a mechanical constraint during the image capture process in order to maximize the likelihood of faithful mapping. The four types of scanners known in the art are drum scanners, flatbed scanners, two-dimensional array scanners and hand scanners.
Once you have decided to purchase a document scanner, it becomes important to understand the specifications that set individual models apart. Although each product may look significantly different, each product is defined by the performance of its components, which are common to all scanners:
Contemporary document scanners typically use either a CCD (Charge Coupled Device) or a CIS (Contact Image Sensor) image sensor. CIS is a more recent innovation developed for cost-effective entry-level consumer scanners. CIS-based scanners are smaller, less costly and consume less power than the CCD-based units, but the trade-off is they produce slightly lower-quality images. For more information read this article.
The scanner resolution specification helps to set a scanner apart from the rest. The resolution figure refers to the number of pixels a scanner can sample/capture and is often measured in dots per inch (dpi).
Higher-resolution document scanner is capable of capturing more information from a given image than lower resolution document scanners and therefore provide greater detail and image quality. High-resolution scanners may also be capable of producing excellent images at resolution settings below their maximum resolution. For example, a 600 dpi scan from a 1200 dpi scanner may be better than a scan at the same resolution from a 600 dpi scanner (all else being equal).
There are two types of scanner resolution: optical and interpolated. What really counts is the optical resolution as interpolation can be performed in most image editing programs (and can, therefore, be ignored). Some manufacturers provide two resolution figures, and it is typically the smaller number that represents the optical resolution. Take 600 x 1200 dpi for example – 600 dpi is the optical resolution.
In terms of optical resolution, 300 dpi is adequate for the average document scan, while 600 dpi should be good enough for high-quality scans and common photo scanning. 1200 dpi or higher is required only for highly-demanding graphics work/photo scanning and 3200 or higher for film/slides.
The bit depth refers to the amount of information a scanner is capable of recording per pixel. The higher the bit depth, the more colour/grey gradations the scanner can record, and this, therefore, results in higher image quality. A higher bit depth also means a larger file size, since more information can be stored per pixel.
Many of the latest document scanners provide bit depths of up to 36 or even 48-bits, which means theoretically that billions of colours can be captured. Generally speaking, scanners with higher bit/colour depths tend to provide better image quality. For most home/office users, 24-bit is sufficient under most circumstances and 36-bit is usually more than enough.
Dynamic range, also known as optical density (OD) or density range, is a measure of the scanner’s ability to record different tones in an image. Dynamic range is measured on a logarithmic scale from 0 to 4 (0.0 represents perfect white, while 4.0 represents perfect black). The dynamic range is actually the difference between the darkest and brightest optical density that the scanner can capture. The bigger the difference, the larger the dynamic range can be, and the better the image quality the scanner can offer.
A document scanner is specifically-designed for mainstream users and do not include a dynamic range specification. If you need a scanner that will produce very high scan quality, the dynamic range has to be taken into account. Most mid-range flatbed scanners have a dynamic range of 2.8 to 3.2, which is more than enough for most home/office users, but if you want excellent results for film, slides or other transparencies, a higher dynamic range of at least 3.3 (3.4 for negatives) is recommended.
There are three major types of connection for scanners: USB, SCSI, and parallel port (already phased out). USB and SCSI are the mainstream interfaces currently and some scanners feature both USB and SCSI interfaces.
The Universal Serial Bus (USB) is popular in both Macintosh and Windows PCs as it outperforms the SCSI interface with its plug-and-play and hot-swappable (you can plug it in or pull it out while your computer is still running) features.
Featuring fast data transfer speeds, the USB2.0 connection supports speeds of up to 480Mbps (60MB/s), while the older USB1.1 connection supports speeds of up to and 12Mbps (1.5MB/s). Some high-end scanners also support the FireWire (IEEE 1394) connection, which is similar in concept to USB and features 400Mbps (50MB/s) transfer speed (IEEE 1394a).
The Small Computer System Interface (SCSI, pronounced “scuzzy”) is applied to some high-end scanners. This type of connection is fast but may require more work to configure and install. Most PCs do not support the SCSI port, and a SCSI controller card needs to be purchased and installed in your computer for a SCSI scanner to be used.
Many SCSI scanners come with controller card and cables already inside the package. If you want to use your own SCSI card instead, please check to ensure compatibility with the scanner and its cables first.
The importance of the speed of a document scanner depends on how often you plan on using it. The speed may not be an issue if a scanner is only used once or twice a day, which is typically the case with most home/personal usage. Of course, things can be totally different for those who are constantly acquiring images or documents.
Generally, the scanning resolution, as well as other scanning settings such as colour depth, has a crucial influence on the scanning speed. Scanning at a higher resolution/colour depth tends to take more time. There are some different ways to measure the speed of a scanner: the time it takes to scan a single page (e.g. 30 seconds); pages scanned per minute (pages per minute, ppm); and ipm (images per minute) – equals to ppm for common scanners, but doubles for duplex scanners since they can scan both sides of a page simultaneously.
The bundled software, which is a very important part of the scanner, is often overlooked by many users. The bundle will probably contain a driver program, colour calibration software, image-editing software and optical recognition software (OCR). But not all manufacturers offer a complete bundle of the above software for all models.
For Windows, the driver program is usually TWAIN compatible. A TWAIN driver allows imaging devices like scanners to be compatible with TWAIN-supported software. Since TWAIN is the industry standard, most bundled software can operate off TWAIN.
Colour calibration software is used to maintain the original colours of the image throughout the processing, which means that what is seen on the monitor and printed out should be reasonably close to the original colours.
Image-editing software, more often than not, offers you “lite” versions of image-editing programs. Basically they can adjust brightness, contrast, colour balance and other image attributes. More costly scanners sometimes include full versions of image-editing software.
Most manufacturers also provide a bundle with full/cut-down versions of optical character recognition (OCR) software, which specializes in transforming the printed text into computer text. Excellent OCR software is able to deal with a variety of languages and text formats.
Which Document Scanner Best Suits Me?
With so many different document scanner products available on the market, it can be hard to pinpoint the scanner product that best suits you. Here are our recommendations categorized by user type – typical usage attributes for reference.
General Home/Office Document Scanner
Most home/office users scan a variety of objects with their document scanners, such as family photos/ film slides, pictures/pages from books and magazines, and transferring printed text into computer-editable text and etc. A flatbed scanner can perform all these tasks.
If your main purpose is to produce images used on websites, an entry-level scanner should be enough, and a 300 dpi resolution is sufficient for good OCR results (when transferring printed text into computer-editable text). A CCD scanner is needed if you demand higher quality scan results or if you want to scan physical objects (such as a motherboard, video card etc.). For users who want to print the scanned images, or demand higher image quality, we recommend opting for at least a mainstream scanner.
As described in the Scanner Types section, most flatbed scanners require a transparency adapter (TPA or TPU) to scan slides, film, x-rays and other transparent originals, while an automatic document feeder (ADF) is needed for high-volume scanning (if the scanner doesn’t have one).
Business/Office Users (or for high-volume scanning) Document Scanner
For tasks involving the scanning of hundreds or even thousands of pieces of paper weekly, or for the conversion of a large number of catalogues into PDF form or any other frequent high-volume scanning requirements, we recommend scanners with the following specifications. You will also find this article extremely useful.
Resolution is not the key concern here and 600 dpi is just fine for this kind of document scanner. What really counts here is the scanning speed – a scanning speed of 30 pages per minute is much more efficient than 10ppm when there is a lot of information to scan and limited time to do it in.
As mentioned above, an ADF (automatic document feeder) can be of great help for high-volume scanning, and duplex scanners are excellent for book scanning as they can scan both sides of a page in a single pass.
Photographic Professional (or for high-quality film/slide/negative scanning) Document Scanner
A dedicated film scanner is optimized for film/slide/negatives scanning and will also produce excellent results for transparency scanning. We suggest you to look for the below specifications when buying a document scanner for this purpose:
I hope this helps. I think this buying guide on best document scanner in India has been complied taking every small detail and every need in mind. Just in case, you still think there is something we could have highlighted, please do leave it in the comment section, we would be happy to assist.