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Lesson 4: Input and Output. Digital Photography MITSAA IAP 2002 Rob Zehner. Outline. Scanners Different types Compare & contrast Printing digital images Different types of printers Compare & contrast Preparing images for print. Why Scan?. Film is a great image capture medium Cheap

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Lesson 4: Input and Output

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lesson 4 input and output

Lesson 4:Input and Output

Digital Photography


IAP 2002

Rob Zehner

  • Scanners
    • Different types
    • Compare & contrast
  • Printing digital images
    • Different types of printers
    • Compare & contrast
  • Preparing images for print
why scan
Why Scan?
  • Film is a great image capture medium
    • Cheap
    • Ultra-high resolution
    • It’s been around for years
  • Digital offers new opportunities
    • Digital printing = no darkroom!
    • Image manipulation, touch-up is easy
    • Use film photos on Web sites, share with friends
flatbed scanners
Flatbed scanners
  • Least expensive kind of scanner ($100-$1000)
  • Optimized for reflective materials (paper, prints)
    • Typically has a small contrast range
  • Can be adapted to scan film with auxiliary light source
    • Not optimized for handling transparencies
film scanners
Film scanners
  • More expensive than flatbeds ($500 - $5,000)
  • Typically have very high contrast range
    • Even good film scanners will not be able to capture the full tonal range of a black & white negative
  • Capable of scanning at 3,000 - 4,000 dpi
  • Usually come with software to make the process easier - scratch & dust removal, etc.
drum scanners
Drum scanners
  • Most expensive
  • Originals are taped to a cylinder, which is spun rapidly and scanned with a single PMT
  • Advantages:
    • Very good sharpness
    • Extremely large contrast range
  • Disadvantages
    • Negatives must be de-mounted, taped, often coated with index-matching oil
scanner fallacies
Scanner fallacies
  • All resolution figures are not equal
    • Sharpness is what is really important
    • Beyond physical resolution limit, more pixels carry no additional information
  • Flatbed + transparency adaptor is not the same as a film scanner
    • Dmax of scanner will determine the results for transparent media
before printing after scanning
Before printing / after scanning
  • Scan to give you the number of pixels you’ll need
    • Printer resolution x output dimension
    • Rule of thumb : 300 ppi is adequate
  • Keep your data stream short
    • Avoid lossy compression (use TIFF, not JPEG)
    • Don’t resize repeatedly
    • Work at full resolution
don t rely on unknown factors
Don’t rely on unknown factors
  • Give image to the printer at exact printer resolution
    • Otherwise, the printer will re-scale it using some unknown algorithm
  • Use color calibration
    • Calibrated input sources
    • Calibrated displays (Adobe Gamma)
    • Calibrated printers
image resizing
Image resizing
  • Film: grain determines enlargement limit
  • Digital: pixellation determines enlargement limit
    • This can be overcome by rescaling the image
    • Software will use an algorithm to generate intermediate pixels
  • Whatever you do, you can’t generate additional information
    • Enlargements will not be sharp when viewed up close
printers ink jet

Cheap to buy

Fairly high resolution

Nice colors

Can handle large paper


Slow in color mode

Supplies are expensive

Photo paper $1/page

Ink cartridges $30

Archival life ??

Epson makes pigment inks they claim will last 100 years

Printers: Ink Jet
  • Ink jet printers work by spraying droplets of colored ink - cyan, magenta, yellow, black
printers dye sublimation

Saturated colors

True 24-bit color at each pixel



Expensive to use

Wasteful of supplies


Printers - Dye Sublimation
  • Work by evaporating dyes from donor sheets onto paper

Printers - Photo Printers

  • Work by variety of processes involving photosensitizing & transferring dyes (e.g. Fujix)
  • Advantages
    • Very low cost per print
    • Very good colors
    • Lightfastness should be similar to traditional photographs
  • Disadvantages
    • Too expensive to own at home
    • Commercial printers can charge large mark-up