SCANNERS
Scanners copy the image of a document - such as a photograph, or a newspaper article and create a digital version of that document so that it can be read by a computer. In computing, a scanner is a device that analyzes an image (such as a photograph, printed text, or handwriting) or an object (such as an ornament) and converts it to a digital image.
FLATBED SCANNER
A Flatbed Scanner is usually composed of a glass pane (or platen), under which there is a bright light which illuminates the pane, and a moving optical array. Colour scanners typically contain three rows (arrays) of sensors with red, green, and blue filters.
Images to be scanned are placed face down on the glass and the sensor array and light source move across the pane reading the entire area. An image is therefore visible to the charge-coupled device only because of the light it reflects. These flatbed scanners are versatile because they can scan flat originals of various sizes. They can even scan small three-dimensional objects (like your hand). Flatbed scanners can also scan slides, x-rays, etc.
HAND SCANNER
Hand scanners are manual devices which are dragged across the surface of the image to be scanned. They typically have a "start" button which is held by the user for the duration of the scan, some switches to set the optical resolution, & a roller which generates a clock pulse for synchronization with the computer.They were popular during the early 1990s and usually had a proprietary interface module specific to a particular type of home computer, usually an Atari ST or Commodore Amiga.A typical hand scanner also had a small window through which the document being scanned could be viewed.
DRUM SCANNERS
Drum scanners, the oldest scanning technology, have a scanning photomultiplier tube, which moves back and forth along a single axis. The use of drum scanners has declined significantly as flatbed scanners based on charge-coupled devices have dropped in price; however, drum scanners are still used for certain high-end applications, such as museum-quality archiving of photographs and for print production of high-quality books and magazine advertisements.
SCANNER QUALITY
Scanners typically read Red-Green-Blue color (RGB) data from the array,process it with some proprietary algorithm to correct for different exposure conditions,and send it to the computer via the device's input/output interface (usually SCSI or USB,or LPT in machines). Color depth varies depending on the scanning array characteristics, but is usually at least 24 bits. High quality models have 48 bits or more color depth.
The other qualifying parameter for a scanner is its resolution, measured in pixels per inch (ppi). As of 2004, a High-end Flatbed Scanners can scan up to 5400 ppi, and a good Drum Scanner has an optical resolution of 8000–14,000 ppi. The higher the resolution, the larger the file.
The third important parameter for a scanner is its density range. A high density range means that the scanner is able to reproduce shadow details and brightness details in one scan.
OUTPUT DATA
The scanned result is a non-compressed RGB image which can be transferred to a computer's memory. Some scanner compresses and cleans up the image using embedded firmware. Once on the computer, the image can be processed with a raster graphics program (such as Photoshop or the GIMP) and saved on a storage device (such as a hard disk).
In common use, scanned pictures are stored on a computer's hard disk, normally in image formats such as JPEG, TIFF, Bitmap, and PNG. Some scanners can also be used to capture editable text. This process is called Optical Character Recognition (OCR).
The amount of data generated by a scanner can be very large: a 600 DPI 9"x11" (slightly larger than A4 paper). Recent scanners can generate this volume of data in a matter of seconds. Therefore, a fast connection is desirable.
Early scanners had parallel connections that could not go faster than 70 kilobytes/second. Professional models adopted the SCSI-II connection, which was much faster although expensive.
Recent models come equipped with USB connections.
Like printers, scanners can be very inexpensive, and many are available for $50. As they become more expensive, they include more features, like better quality scanning and larger scan areas (so that you can scan larger documents).
What costs comes with scanners?
Unlike printers, scanners do not use ink or any other kind of consumable. Therefore, once you have purchased the scanner, there should be no other costs.
What are the advantages of scanners?
Ability to scan documents into your PC.
Disadvantages?
None.
INFRARED CLEANING
Infrared cleaning is a technique to remove dust and scratches from film. Most modern scanners incorporate this feature. Infrared cleaning works by scanning the film with infrared light. From this, it is possible to detect dust and scratches that cut off the infrared light and they can then be automatically removed based on their position, size, shape and surroundings.
Scanner manufacturers usually have their own name attached to this technique. For example, Epson, Nikon, Microtek and others.
DOCUMENT SCANNING
The scanning or digitization of paper documents for storage is quite different from the scanning of pictures though it uses some of the same technology. While document scanning can be done on general-purpose office scanners, in major operations it is performed on dedicated, specialized scanners, manufactured by companies like Canon, Fujitsu, Kodak, and others.
Document scanners have document feeders, generally larger than those found on copiers or all-purpose scanners. They scan at lower resolution than other scanners, usually in the range 150dpi to 300dpi. A lot of scans can be made at high speed, traditionally in grayscale but now in color as well. Many are capable of duplex (two-sided) scanning at or near full speed (20ppm (pages per minute) to 150ppm).
Scanners copy the image of a document - such as a photograph, or a newspaper article and create a digital version of that document so that it can be read by a computer. In computing, a scanner is a device that analyzes an image (such as a photograph, printed text, or handwriting) or an object (such as an ornament) and converts it to a digital image.
FLATBED SCANNER
A Flatbed Scanner is usually composed of a glass pane (or platen), under which there is a bright light which illuminates the pane, and a moving optical array. Colour scanners typically contain three rows (arrays) of sensors with red, green, and blue filters.
Images to be scanned are placed face down on the glass and the sensor array and light source move across the pane reading the entire area. An image is therefore visible to the charge-coupled device only because of the light it reflects. These flatbed scanners are versatile because they can scan flat originals of various sizes. They can even scan small three-dimensional objects (like your hand). Flatbed scanners can also scan slides, x-rays, etc.
HAND SCANNER
Hand scanners are manual devices which are dragged across the surface of the image to be scanned. They typically have a "start" button which is held by the user for the duration of the scan, some switches to set the optical resolution, & a roller which generates a clock pulse for synchronization with the computer.They were popular during the early 1990s and usually had a proprietary interface module specific to a particular type of home computer, usually an Atari ST or Commodore Amiga.A typical hand scanner also had a small window through which the document being scanned could be viewed.
DRUM SCANNERS
Drum scanners, the oldest scanning technology, have a scanning photomultiplier tube, which moves back and forth along a single axis. The use of drum scanners has declined significantly as flatbed scanners based on charge-coupled devices have dropped in price; however, drum scanners are still used for certain high-end applications, such as museum-quality archiving of photographs and for print production of high-quality books and magazine advertisements.
SCANNER QUALITY
Scanners typically read Red-Green-Blue color (RGB) data from the array,process it with some proprietary algorithm to correct for different exposure conditions,and send it to the computer via the device's input/output interface (usually SCSI or USB,or LPT in machines). Color depth varies depending on the scanning array characteristics, but is usually at least 24 bits. High quality models have 48 bits or more color depth.
The other qualifying parameter for a scanner is its resolution, measured in pixels per inch (ppi). As of 2004, a High-end Flatbed Scanners can scan up to 5400 ppi, and a good Drum Scanner has an optical resolution of 8000–14,000 ppi. The higher the resolution, the larger the file.
The third important parameter for a scanner is its density range. A high density range means that the scanner is able to reproduce shadow details and brightness details in one scan.
OUTPUT DATA
The scanned result is a non-compressed RGB image which can be transferred to a computer's memory. Some scanner compresses and cleans up the image using embedded firmware. Once on the computer, the image can be processed with a raster graphics program (such as Photoshop or the GIMP) and saved on a storage device (such as a hard disk).
In common use, scanned pictures are stored on a computer's hard disk, normally in image formats such as JPEG, TIFF, Bitmap, and PNG. Some scanners can also be used to capture editable text. This process is called Optical Character Recognition (OCR).
The amount of data generated by a scanner can be very large: a 600 DPI 9"x11" (slightly larger than A4 paper). Recent scanners can generate this volume of data in a matter of seconds. Therefore, a fast connection is desirable.
Early scanners had parallel connections that could not go faster than 70 kilobytes/second. Professional models adopted the SCSI-II connection, which was much faster although expensive.
Recent models come equipped with USB connections.
Like printers, scanners can be very inexpensive, and many are available for $50. As they become more expensive, they include more features, like better quality scanning and larger scan areas (so that you can scan larger documents).
What costs comes with scanners?
Unlike printers, scanners do not use ink or any other kind of consumable. Therefore, once you have purchased the scanner, there should be no other costs.
What are the advantages of scanners?
Ability to scan documents into your PC.
Disadvantages?
None.
INFRARED CLEANING
Infrared cleaning is a technique to remove dust and scratches from film. Most modern scanners incorporate this feature. Infrared cleaning works by scanning the film with infrared light. From this, it is possible to detect dust and scratches that cut off the infrared light and they can then be automatically removed based on their position, size, shape and surroundings.
Scanner manufacturers usually have their own name attached to this technique. For example, Epson, Nikon, Microtek and others.
DOCUMENT SCANNING
The scanning or digitization of paper documents for storage is quite different from the scanning of pictures though it uses some of the same technology. While document scanning can be done on general-purpose office scanners, in major operations it is performed on dedicated, specialized scanners, manufactured by companies like Canon, Fujitsu, Kodak, and others.
Document scanners have document feeders, generally larger than those found on copiers or all-purpose scanners. They scan at lower resolution than other scanners, usually in the range 150dpi to 300dpi. A lot of scans can be made at high speed, traditionally in grayscale but now in color as well. Many are capable of duplex (two-sided) scanning at or near full speed (20ppm (pages per minute) to 150ppm).