Indian Talent, Global Content
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Indian Talent, Global Content |
January 2009: What's in the breeze |
How to Buy a Scanner?
Most offices and homes today have a scanner - thanks to its ease of use and the steep decline of cost over the years. Further, the hundreds of web sites that sprout up everyday, multimedia applications, e-books, digital documents, and other needs have driven the demand for this equipment. What does a scanner do? It scans a hard-copy document or a photo, stores it in its memory and simultaneously displays the image on the monitor. The scanner then allows you to save the scanned image - in a digital format - to your PC. What's more, using a scanner and OCR (Optical Character Recognition) software, you can scan text pages and transform them into editable computer files - you don't need to recreate a document from scratch. Scanners have other creative uses too. You can even scan smaller, thinner, and lighter objects that do not break, pressurize, or scratch the scanner glass. Say you want to create a background of bread slices for an e-learning project about bread making: simply place the bread slices close to each other, gently close the cover, and scan! You can find a wide-range of scanner models in the market. Do you want to scan long pages or just small portions of text? Or, do you want to scan negatives? A clear picture of the job that you expect the scanner to do and, of course, your budget, paves the way for better purchase decisions. Here are some tips to help you select the right scanner: Scanner Models (1) Flatbed scanners: Most scanners you see in offices and homes are flatbed scanners. Such devices have flat scanning surfaces. To scan a page or photo, place it on the glass surface, close the cover, and click the scan button. The scanner digitizes the document and lets you save the entire image, or only a part of it, to your hard disk. If you have an appetite for technicalities, here’s a brief overview of the technology that makes this equipment tick: Flatbed scanners use either the charged coupled device (CCD) or the contact image sensor (CIS) technology. CIS-based scanners are a recent innovation. Although CIS models produce slightly lower-quality scans than their CCD counterpart, they have two benefits: smaller file sizes and lesser power consumption. Many entry-level devices use the CIS; higher-end flatbeds typically use the older CCD technology. (2) Handheld scanners: Want to scan documents on the go? Use a handheld scanner. Pen-sized models of these devices can fit in your pocket! Handheld scanners are a recent entry in the scanner market. They are lightweight and work on either rechargeable batteries or require a hosting computer. Handheld scanners can scan not only snippets of text, but also an entire page in seconds. Portable scanners are ideal for anyone who has a need to scan on the move. In particular, these models can benefit researchers, students, accountants, lawyers, and graphic designers. To scan a page, just place the scanner on the page, press the button, and glide the scanner over the page. Then, connect the scanner to your PC or laptop to save the image in the device’s memory to your computer. Some models allow you to scan only word-by-word, like you highlight text with a highlighter pen, and therefore, take more time to capture the text. (3) Rotary Drum Scanners: As high-end scanning devices, drum scanners give the highest digital quality with a resolution that can be more than 11000 dpi. These scanners use photomultiplier tube (PMT) technology. Typically, only service bureaus use drum scanners, because they are expensive. When you need the best quality scanned images from originals, you should approach a bureau that can do the job for you. Resolution This refers to the number of dots that a scanner can create in an inch – the higher the number of dots in an inch, the sharper the scanned image. Advanced flatbed scanners support a resolution in the range 2400 by 2400 to 4800 by 9600 dpi (dots per inch). Your applications however, may not need such a high resolution. For example, if you intend to scan small photos to use them in a web page, a 100 dpi scan is more than adequate. Any entry-level scanner can easily perform this task. On the other hand, if you want to enlarge smaller images, select a 1200 dpi or 2400 dpi resolution scanner. Note, that for such work, you have to scan the image at a highest possible resolution to maintain the quality of the image. Be aware though that high resolution scans not only consume more time but also the hard disk space. Scan Area Low-end scanners have a letter-size scan area - 8.5 by 11.7 inches. If you're a home user this scan area may be adequate. If you're a business user, you should opt for a scanner that has a scan area of 8.5 by 14 inches. With a larger scan area, you have the flexibility to scan maps, legal-size documents, newspapers, and drawings. Automatic Document Feeder (ADF) Do you want a scanner for batch jobs? For example, you may have a need to scan thousands of pages. Such tasks definitely require a scanner with an ADF for getting the job done quickly. You also need an ADF to scan pages that are longer than the scanning surface. You can find scanner models that have either a built-in ADF or an ADF supplied as an accessory. Dynamic Range You’ll see dynamic range (or Dmax) in the specifications of some high-end scanners. Scanners with a higher dynamic range produce sharper images, because such scanners have the ability to capture gradations from the lightest to darkest parts of an image. Look for a scanner that has a Dmax value of at least 3.2. Color Depth / Scan Depth Measured in bits per pixel, color depth refers to the number of colors a scanner can recognize and save. A scanner can usually capture more data about color than its driver software can handle and, therefore, may not be able to save all the data. In this context, scanner specs have two items for color depth: (1) Internal Scan Depth - the color data the scanner can recognize and Most modern scanners have the same external and internal scan depth. For a majority of uses, 24-bit (16.7 million colors) external scan depth should suffice. Transparency Adapter A transparency adapter, either built-in the scanner or supplied as a separate module, facilitates you to scan negatives, slides, and film strips. A template holds in place the negative you want to scan. The template’s size depends on the scanner model. While some scanners have templates than can hold just one negative, other models can accommodate three slides. Doctors, among others, would find scanners with transparency adapters useful to scan x-rays and use it in telemedicine, presentations, and as e-mail attachments. Software When you buy a scanner, the scanner software CD is bundled with it. You will have to install the software to use the scanner. Depending on the manufacturer and the model, the package may also contain goodies like basic or advanced image-editing/OCR software.
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