Scanners
Technology
 | A scanner is a device that can read text or illustrations printed on paper and translate the information into a form the computer can use. |
| It works by digitizing an image -- breaking the image down into a matrix of squares for which color at each point can be captured. This is typically measured in dots per inch (dpi). |
| Color depth as color or gray scaling is handled in ranges from 1 to 24 bits. |
| Higher bit rates, often seen in marketing promotions (e.g., "the XXX scanner captures at 40 bits), includes color, brightness, and other data that can improve the quality of the capture. |
| The resulting matrix of bits, called a bit map, can then be stored in a file, displayed on a screen, and manipulated by programs. |
| Scanners do not capture text as characters in a direct fashion. Optical character recognition (OCR) software is required that reads the bitmapped image and interprets the characters. OCR quality is often a function of cost. |
Interfaces to computers include:
| SCSI - fast interface, long term compatibility. |
| USB - very fast interface, becoming popular as USB takes hold. |
| Serial (not common), very slow |
| Parallel - slow, but cheap |
USB: short for Universal Serial Bus, a new external bus standard that supports data transfer rates of 12 Mbps (12 million bits per second). A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, and scanners. Also supports hot plugging (plug and play). (from ZDNet)
Typical scanners are flat bed types...
| Hardware includes movable scanning carriage with lighting. |
| Some require warm-up (especially cheaper models) of 30-60 seconds. |
| Scan rates range from 100 to 600 dpi with interpretation to 1200/2400 dpi. |
| More expensive scanners have auto-scan (push-button capabilities), auto-feed for content production, and very high scan rates. |
| Integration with copier, fax technology is more common also. |
Vendors
A number of scanner manufacturers are available. Consider corporate history, how long have they been creating products, and referrals as measures for picking a product.
| Hewlett Packard |
| Mustek |
| Kodak |
Pricing
| Ranges from $60 to thousands of dollars. |
| Inexpensive scanners ($60-$200) are good for home, small office uses. |
| More expensive scanners offer increases in speed, production (automatic scanning), and quality. |
Tips and Techniques
| Pick a scanner that fits your cost and "use model." Do not spend a lot of money on something that you will not be using a lot, on the other hand, don't be cheap if you will be using it a lot or speed is important. |
| Scan images at higher dpi rates than you need, it is easier to reduce an image an image after it has been scanned than to keep going back. |
| Clean the scanning window!! |
| Glossy items (photos, magazine covers) can be tricky, watch the brightness and contrast when scanning. |
| OCR, even at 99% accuracy may sound like a good thing, but that means that you have an average of one error for every two lines of text (or about 20 errors a page). Also scan the cleanest document possible. |
Cameras
Technology
| A digital camera stores images digitally (bitmap typically) rather than recording them on film. |
| Once a picture has been taken, it can be transferred to a computer manipulated with a graphics program and printed. |
| Digital camera photos are limited by the amount of memory in the camera, the optical resolution of the digitizing mechanism, and, finally, by the resolution of the final output device. |
| Currently, only the most expensive digital cameras connected to the best printers can produce film-quality photos. |
| The big advantage of digital cameras is that making photos is both inexpensive and fast because there is no film processing. |
Technology considerations:
| Camera mechanism: lens type, shutter action, flash |
| Digitizing mechanism (CCD devices that sense light and output digital information), size of CCD surface is important; range is from 320 X 640 to 3+ megapixels. |
| Memory: more memory for storing more images, also speed of the memory . Two types of memory: media (floppy, CD, etc.) and chip-based (memory sticks, etc.). |
File formats supported by cameras:
| Compressed JPEG - including two or more levels of compression. |
| Bitmap (no compression) |
| MPEG (limited by memory) |
Vendors
There are two general classes of vendors...
- Traditional camera makers who are doing digital - Canon, Kodak, Sony
- Computer/hardware makers who are doing cameras - Toshiba, Casio
Generally speaking the traditional camera makers have better "cameras" while the computer/hardware makers do better with the digital technologies (this is a very broad generalization).
Pricing
Low Cost: up to 640X480, limited storage, "toys" - $50-$200
Medium Cost: up to 2 megapixels, 1-32 MB storage, good home, amateur, office use - $200 - $700
High Cost: very high pixel and storage capabilities, professional camera features, photo-quality or professional uses - $1000 plus
Tips and Techniques
| Technology is getting better and cheaper. Buy the most for the cheapest that you need. |
| If you are using the camera for web or email--remember the screen is still 72-96 dpi. Shooting high resolution images may not benefit you very much. On the other hand, if you have the capability, use it and then modify with a graphics program. |
| Make sure you understand the various features of your camera (lens/focal settings, special effects, lighting modes, flash usage)-experiment to develop your skills. |
Clip Art Services
Technology
Web-based, online resources often containing thousands of images in various formats such as bitmap, JPG, GIF, TIFF, metafiles, etc.
Many of these resources use search engines (organized by grouping (e.g., people or cars) or topic, specific item (e.g., Abraham Lincoln) type of file, etc.) to help customers locate images. Searching through choices is often time consuming.
Vendors
| www.arttoday.com |
| www.clipart.com |
Some vendors offer:
| Font downloads |
| Conversion services |
| Custom development |
Pricing
Prices vary from pay-as-you-go to periodic fees (monthly, annually). Some services offer "classes" of services (e.g., more/less images).
Tips and Techniques
| Check out the service before you buy, some have large collections that may be of poor quality or of limited interest (e.g., 1000 pictures of a rose..., etc.). |
| Make sure all images are copyright or royalty free OR that you know what limitations exist. |