Graphic Tablet

A graphics tablet (or digitizing tablet, graphics pad, drawing tablet) is a computer input device that allows one to hand-draw images and graphics, similar to the way one draws images with a pencil and paper. These tablets may also be used to capture data of handwritten signatures.
A graphics tablet (also called pen pad) consists of a flat surface upon which the user may "draw" an image using an attached stylus, a pen-like drawing apparatus. The image generally does not appear on the tablet itself but, rather, is displayed on the computer monitor. Some tablets however, come as a functioning secondary computer screen that you can interact with directly using the stylus.
Some tablets are intended as a general replacement for a mouse as the primary pointing and navigation device for desktop computers.
A graphics tablet is an input device used by artists which allows one to draw a picture onto a computer screen without having to utilize a mouse or keyboard. A graphics tablet consists of a flat tablet and some sort of drawing device, usually either a pen or stylus. A graphics tablet may also be referred to as a drawing tablet or drawing pad. While the graphics tablet is most suited for artists and those who want the natural feel of a pen-like object to manipulate the cursor on their screen, non-artists may find them useful as well. The smooth flow of a graphics tablet can be refreshing for those who find the mouse to be a jerky input device, and repetitive stress injuries such as carpal tunnel syndrome are less likely when using a graphics tablet.
A graphics tablet may come in a range of sizes, from smaller 3" by 4" (7.6 by 10.2 cm) models to larger 7" by 9" (17.8 by 22.9 cm) ones. Even larger graphics tablets exist, up to enormous 14" by 14" (35.6 by 35.6 cm) tablets targeted towards professional designers and architects. Size is the major factor in determining cost for a graphics tablet, however, and one should expect prices to ramp up dramatically at the high end of the size spectrum. A good range of pressure sensitivity in the drawing surface of your graphics tablet is also something to look for. High pressure sensitivity, ideally at least 512 levels, allows you to control a number of aspects of your drawing, including color and line thickness, simply by pressing the stylus more or less heavily, mimicking drawing with an actual pen.
The stylus included with a graphics tablet is also an important consideration for the consumer. A stylus may be either attached to the tablet by a cord or tether-free. Corded tablets do not require batteries, but many people find the cord severely limiting to their range of motion. A good stylus will also have function buttons on the side, so that you can perform common actions, such as switching a tool in a drawing program from paint to erase, without having to use the mouse or keyboard.
Wacom is the most well known manufacturer of graphics tablets, and incredibly well respected. They have many different models, covering everything from amateur to professional artists, spanning the size range, and with many bells and whistles. At the low end of their product line, one can expect to pay about US$100 for a good graphics pad, while their high-end products may cost just over US$500. Other manufacturers include Aiptek, which has a number of models, including some with a cordless mouse in place of the stylus; KB Gear, which makes a graphics tablet targeted towards teens; and CalComp, which makes tablets primarily for architects and designers.
Also referred to as a digitizing tablet, graphics pad, or drawing tablet, a tablet is an alternate type of input device that can be used in place of, or in conjunction with, a mouse, trackball, or other pointing device. The tablet consists of two parts, a flat surface for drawing, and a pen, stylus, or puck that is programmed to work with the tablet. Usually, you also get a pen holder, and some tablets even come with a cordless mouse that works on the tablet surface. Even non-artists may choose to use a tablet because it offers a more ergonomic method of input that can reduce the likelihood of developing repetitive strain injury. Let's explore some of the common features of graphics tablets...
Size
Size is one of the first factors you'll need to consider in choosing a tablet. Bigger is not necessarily better. For home users and hobbyists, the most common sizes are 4" by 5" and 6" by 8". CAD users, artists, and technical illustrators may desire a larger surface area, but the price escalates as the size increases. Remember, the larger your tablet surface is, the more you will need to move your arms. Many people prefer a smaller tablet to minimize arm motion. However, this may feel unnatural to an artist who is used to drawing or painting with large sweeping motions. Another important thing to know about tablet size is that the dimensions given almost always refer to the input surface area of the tablet. The actual footprint of the tablet can be as much as 4 to 5 inches larger than the input area. Keep this in mind as you shop, or you may be surprised that your tablet takes up much more desktop space than you may have considered. My 6" by 8" Wacom Intuos tablet, for instance, has a footprint of 10" by 13.5".
Until recently, the popular sizes of graphics tablets have been 4x5, 6x8, and 9x12 which matches up neatly to the 4:3 aspect ratio of traditional computer monitors. But starting in the mid-2000s there has been a proliferation of widescreen aspect ratio monitors. Because of this, Wacom has begun producing wide-format graphics tablets to better correspond with the aspect ratio of widescreen monitors and for users working with multiple monitors. Although it's nice, it's not necessary that your graphics tablet match the aspect ratio of your monitor, because the tablet software takes care of the mapping.
Interface
The interface is how your tablet connects to your computer. Most tablets these days have a USB interface which is ideal since most computers in use today support USB. USB devices are hot swapable so you'll be ale to move the tablet more easily for use on multiple computers or just to get it off the desk when you need to.
If you have a very old computer that does not support USB, you'll need to choose a tablet with a serial interface. If you need a serial interface, be sure your computer has an available serial port that does not conflict with another device. If you have both a serial mouse and a serial modem (rare these days), proceed with caution, because you could face a conflict if you add a serial tablet. A tablet with a USB interface gets its power from your computer, but a serial tablet requires a separate power connection, so you'll want to make sure you have an available outlet that can accommodate a medium-sized transformer.
Bluetooth is another option for connecting a graphics tablet to your computer without the use of wires. Bluetooth is a wireless protocol frequently used for connecting electronics devices. Currently, Wacom is the only manufacturer I know of producing a Bluetooth-capable tablet, the Graphire Bluetooth, which can connect to your computer without wires.
Pen/Stylus and Accessories
Your tablet should come with a pen that feels comfortable and natural in your hand. Find out if the stylus requires a battery. A battery will not only require occasional replacement, but it will make the pen heavier, too. Your pen may be tethered or free. If the pen is untethered you'll have to be more careful about losing or misplacing it. If the pen is tethered, make sure you can choose which side of the tablet to attach the pen. Many pens will also have a switch or buttons built onto the pen, and some pens have an erasing end. This is an excellent feature because the buttons can be programmed for specific functions such as a right-click or double-click, and the erasing tip can perform a delete function in one swipe, or automatically activate the eraser tool in your graphics software. Some tablet manufacturers offer additional pens and other pointing tools that you can program independently. When using these optional accessories, your tablet should recognize it as a new tool and use the customized preferences you have specified for that specific tool.
Pressure-sensitivity
Pressure level refers to the sensitivity to pressure on the surface of the tablet. Most tablets have 256, 512, or 1024 pressure levels. The pressure-sensitivity can control line thickness, transparency, and/or color. The higher the pressure-sensitivity, the more responsive and natural your tablet will feel and the more control you will have.
Top 10 Pressure-Sensitive Graphics Tablets
These are the most popular brands and models of graphics tablets available in the US. The pressure-sensitive graphics tablets featured here are well-suited to both professional and home users who will be using the tablet for photo editing and digital art, or as a mouse replacement for everyday computing.
Wacom Intuos3 6X8 - PTZ630
The Intuos3 pen provides 1,024 levels of pen tip and eraser pressure sensitivity, tilt sensitivity, is batterly-free and cordless, and features a programmable DuoSwitch and soft grip. It also comes with a cordless, programmable 5-button optical scroll mouse. The tablet features 2 touch strips, 8 ExpressKeys, and comes with a pen stand. With Intuos, you also have the option of purchasing additional programmable accessories. (Footprint ~13x10")
Wacom Bamboo Fun Medium - CTE650
The Bamboo Fun tablet from Wacom is the successor to the Graphire4 series of consumer level pen tablets. Improving on the Graphire4 model, Bamboo Fun has an updated look, a wide-format active area, a new textured feel to the tablet surface, and a finger-sensitive touch ring for zooming and scrolling. For creative work like painting, drawing, and touching up photos, the medium size Bamboo Fun tablet is ideal. It has a fresh, fun look, and performs well. Unlike the Bamboo standard tablet, Bamboo Fun comes with a mouse and a bundle of creative software including Adobe Photoshop Elements 5 Win/4 Mac, Corel Painter Essentials 3, and Nik Color Efex Pro 2 GE. (Footprint: 11.0" x 9.3")
Wacom Graphire Bluetooth Wireless Tablet - CTE630BT
Graphire Bluetooth is slightly older and not as advanced as Bamboo and Intuos3, but it does have one big advantage — no wires. You can use the Graphire Bluetooth in the range of 30 feet and for up to 25 hours between charges. However, it does require that your computer have a Bluetooth adapter, and you will need a power source to charge the batteries on occasion. The power adapter is included, but the Bluetooth adapter is not. Many newer laptops come with built-in Bluetooth capabilities.
Wacom Intuos3 6x11 Wide Format USB Tablet - PTZ631W
Now you can get the Intuos in a wide format aspect ratio for working with a widescreen monitor or dual displays. The footprint of the Intuos3 6x11 is 16.5 inches wide x 10.3 inches deep and includes two sets of ExpressKeys and Touch Strips. If you don't have the desk space or need to spend a little less, there is also a 4x6 wide format Intuos3 with a smaller footprint of 10.6 by 8.5 inches and one set of ExpressKeys. Both models offer the highest level of pressure sensitivity and the advanced customization options and accessories available for the Intuos line.
Wacom Bamboo Pen Tablet - MTE450
For the price, Bamboo is an excellent entry-point to the Wacom product line. Bamboo is designed primarily for office tasks rather than artistic work. Although it functions just fine in creative software with pressure support, Bamboo does not come with software and is intended to be used with the built-in pen features of Windows Vista, Microsoft Office, and Mac OS X for marking up documents, jotting notes, and writing your signature. Of course, it can also be used as an alternative to the mouse to avoid repetitive stress fatigue. (Footprint: 7.88" x 7.36")
Wacom Intuos3 9X12 USB Tablet - PTZ930
The larger size of the Intuos 9x12 tablet will let you achieve the wider, sweeping strokes some artists prefer. It comes at a cost in desk space, though — this tablet has a footprint of about 18 by 14 inches. Except for the larger size, it is identical to the Intuos3 6x8 with the same software bundle and optional accessories.
DigiPro 8x6 Graphics Tablet - WP8060
The DigiPro drawing tablet is an inexpensive, yet capable, pressure-sensitive pen tablet for budget conscious users. It's not flashy or feature packed, but it does the job it's supposed to do. The DigiPro tablets will also work on older systems, including Windows 98Se and higher, Mac OS 9, and Mac OS X. If you're curious about using a graphics tablet, but don't want to spend a lot of money, the DigiPro drawing tablets are a solid choice.
Aiptek 10x6 Slim Tablet - ST12
If you want a larger tablet, but the budget is tight, Aiptek's Slim Tablet is hard to beat. This is a wide format, slim graphics tablet with cordless pen and a 10x6 inch active area. It feature 29 programmable macro keys around the sides of the tablet, s a resolution of 1000 lpi, and 1024 levels of pressure sensitivity. I have not used this particular brand of tablets, but have received many comments from happy Aiptek tablet users.
DigiPro 5.5x4 Graphics Tablet - WP5540
If you're extremely tight on budget, the DigiPro WP5540 can be purchased for less than $50. It has all the features of the WP8060 in a smaller size and lower price to match.
Wacom Cintiq 21UX 21.3" Interactive Pen Display
It's pricey, but as long as you can afford it, who wouldn't want to draw right on the computer screen? The Cintiq combines an LCD monitor with a pressure sensitive tablet surface, so you can do just that. The 21.3 inch Cintiq includes an adjustable stand that allows the display to be rotated, inclined, or detached. It also features a 2-button Grip Pen, 8 ExpressKeys and 2 Touch Strips, 1024 levels of pressure sensitivity, and a 1600x1200 resolution LCD with DVI or VGA video input. For Windows and Macintosh.
Tactile graphic input/output tablets could be a valuable support for blind people reading text illustrated with drawings, creating drawings, using software with a graphic user interface, reading maps, or using electronic communication media. The construction of tablets containing conventional tactile elements is precluded not by fundamental technical problems but by the costs. We show that this problem could be overcome by the use of very simple tactile elements integrated in the tablet and driven by an electrorheological fluid.In our solution the tactile surface can be used also as an input tablet allowing immediate manipulation of perceived objects, and creation of drawings. Furthermore, by passive observation of the user's reading actions the system may support the blind in an intelligent manner, e.g. by presenting automatically additional informations about the object (text or graphic) just being touched. Beyond the description of the technological aspects of such a tablet we deal with its integration into a personal computer system, and give an overview on possible applications.

References

About.com - Before You Buy a Graphics Tablet

Gray, Elisha (1888-07-31), Telautograph, United States Patent 386,815
http://en.wikipedia.org/wiki/Digitizing_tablet

http://www.wisegeek.com/what-is-a-graphics-tablet.htm

http://graphicssoft.about.com/od/aboutgraphics/a/graphicstablets.htm

http://graphicssoft.about.com/od/aboutgraphics/tp/graphicstablets.htm

Fricke, Joerg and Helmut Baehring. Design of a Tactile Graphic I/O Tablet and its Integration
into a Personal Computer System for Blind Users. Department of Computer Science.
Fern Universitaet Hagen.