Notes from January 9, 2003 meeting of the Rochester Genealogical Society, Computer Interest Group. The meeting was held at Brighton High School, room 262 There were 47 attendees including 3 visitors.

Roy Thurston, Rochester Genealogical Society - Vice President/Computer Interest Group opened the meeting and requested new attendees to identify themselves. Jim Hall noted that newly paid members will be listed in the Spring Hear Ye in early March.

Bob Coomber noted that there were only a couple of rooms available for the Salt Lake City trip in early May 2003.

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TECH TALK

Acronyms presented were CCD, TWAIN and OCR. The definitions are listed at the end of these notes.

A problem with changing an Epson printer cartridge was referred to the manual where changing a defective cartridge is described. It was also recommended that a solvent cleaner for the cartridges is usually available at the Computer Show at the dome, where replacement inks are sold.

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MAIN PROGRAM

Agenda:

1. Scanning Technology

2. Definition of a scanner

3. How a scanner works

4. How are images stored

5. Scanner features and availability

6. How to install a scanner

7. How's and What's in scanning use

8. Questions and Answers

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Scanning Technology: Scanner Definition

• Device that reads a printed page

• Converts it to a graphics image usually for additional processing by a computer

• It does not recognize the content of the material it is scanning

• Everything that is scanned is converted to a pattern of dots

• The scanned dots are organized by one of two methods

  1. Bitmap-based

     • Bitmap based images are generally used for pictures

     • File Extensions - PSD, JPG, GIF, TIF, BMP

  2. Vector-based

     • Vector based images are generally used in CAD/CAM applications (precise measurements)

     • File Extensions - EPS, AL, CDR or DWG

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Scanning Technology: How a scanner works

• The lamp illuminates the target

• The light is reflected off the target via a mirror to the Charge Coupled Device (CCD)

• The CCD analyzes the incoming light & sends the results to your computer as numbers 0-255

• The stepping motor moves the light and the cycle is repeated until the area is scanned

• Scanner resolution is important
  DPI is a combination of the Optical resolution of the CCE and the Stepping Speed of the motor
  300 x 600 dpi scanner has a 300 dpi CCD and the motor goes slow enough to scan 600 lines per inch

• Hardware Interpolation is done by a IC chip that generates data by averaging the color of adjacent dots

• Software Interpolation can be used to achieve the same results sometimes even better]

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Scanning Technology: How are images stored ?

• Before the scanning process takes place, you must select one of four scanning modes: Line Art, Halftone, Grayscale or Color

  1. Line Art

     • Requires the least amount of memory

     • Only Black & White information is stored

     • No shades of gray

     • Only 1 bit of data is stored

     • Most useful for text or line drawings

  2. Halftone

     • One bit of data is stored as in line art

     • Displayed as patterns of dots which fool our eyes into seeing gray

     • Manipulating arrangement of dots gives shades

     • Images in newspapers are halftones

  3. Grayscale

     • Equivalent to black and white picture

     • Each pixel is assigned a number value from 0-255

     • 0= black, 255=white, 1-254 shades of gray

     • Each pixel requires 8 bits of storage

  4. Color

     • Largest & most complex to store

     • TV's and computer monitors mix red, green and blue to display all colors visible to the human eye

     • If you looked at screen with a high powered magnifying glass, you would see a grid

     • Each dots intensity is varied at 256 levels

     • Each pixel has 3 dots - red, green and blue

     • Because the dots are so small, the human eye blends them together

     • There are 16.77 million combinations of color for each pixel

     • 8 bits time the three colors
       File size = (Resolution x Horizontal size) x (Resolution x Vertical Size) x Scan Mode - - - where scan mode = 1/8 for Line Art and Halftone, 1 for Grayscale and 3 for Color

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Scanning Technology: How are images stored ?

1. *.TIF (Tagged Image File Format)

   • Supports Monochrome, Grayscale & 24 bit color

   • TIFF does support compression, but it is only 1.5:1 to 2:1

   • With significant white space such as a text document 20:1 is achievable

   • There are some compatibility issues and, therefore, not recommended

2. Bitmap Image Formats (*.BMP (BitMaP file))

   • Native bitmap file available to every Windows application

   • Largest file format because no compression

   • Handles all four scanning modes

   • Size is probably a reason for not using this format

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Scanning Technology: Scanner Features

• Main feature is resolution / How much is enough

  • Interesting fact, magazines are scanned at 200 dpi

  • Scanners can be purchased that have 2400 dpi

  • Ink jet printers can print at up to 2400 dpi

  • Higher resolutions require premium paper

  • Most printers are more in the range of - 600 dpi

  • Scanning at 200 dpi (1/3 600) results in "best" picture printing

• 30 bit and 36 bit scanners - more is better?

  • Files only hold 24 bit pictures

  • Technology is supposed to allow the software to select the 24 bits of data that best represent the original image

  • Some of the newer units support this feature

  • User selects which bits to be saved by changing the Gamma curve
    A Gamma example was presented.

• List of features

  • 600 dpi is reasonable

  • 24 bit color is acceptable

  • USB connection easiest set up

  • Flat bed design

  • High end scanners have paper feeders which is unnecessary for home use

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Scanning Technology: Availability

• Scanners available where ever computers are sold

• BJ's and Sam's have good prices

• Sale prices at Office Max, Office Depot, Best Buy, CompUSA, and Staples are tough to beat

• Watch for rebates

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How to install a scanner

• Installing the Canon CanoScan N67OU:

• USB connection (no external power supply)

• Use CD that came with unit

• Select item / picture to be scanned

• Place on platen glass ensuring that it is parallel to the edge of the glass

• Use Photo Processing software to acquire image

• Select Mode i.e. color, grayscale or line art

• Crop image as necessary

• Adjust - primarily brightness and contrast

• Any picture or item you might want to e-mail

• Building photo albums

• Saving heirloom photographs

• Capturing electronically copies of documents

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A question and answer period ensued, and Chuck Bliley offered many tips from his vast experience.

Paul was given a well deserved round of applause for an excellent presentation.

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TECH TALK ACRONYMS

CCD ( Charge Coupled Device). An electronic memory that can be charged by light. CCDs can hold a variable charge, which is why they are used in cameras and scanners to record variable shades of light. CCDs are analog, not digital, and are made of a special type of MOS transistor. Analog to digital (ADC) converters quantify the variable charge into a discrete number of colors.

TWAIN ( Technology Without An Interesting Name). A programming interface that lets a graphics application, such as an image editing program or desktop publishing program, activate a scanner, frame grabber or other image-capturing device.

OCR. (Optical Character Recognition). The machine recognition of printed characters. OCR systems can recognize many different OCR fonts, as well as typewriter and computer - printed characters. Advanced OCR systems can recognize hand printing.

When a text document is scanned into the computer, it is turned into a bitmap, which is a picture of the text. OCR software analyzes the light and dark areas of the bitmap in order to identify each alphabetic letter and numeric digit. When it recognizes a character, it converts it into ASCII text. Hand printing is much more difficult to analyze than machine-printed characters. Old, worn and smudged documents are also difficult. Scanning documents and processing them with OCR is sometimes as much an art as it is a science.

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wishes to thank Gloria Church for her continuing keyboarding of these handwritten notes, and Dick Halsey for preparing these notes for addition to the Roots/RGS web site.

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