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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

MITSAA

IAP 2002

Rob Zehner

outline
Outline
  • 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
Advantages:

Cheap to buy

Fairly high resolution

Nice colors

Can handle large paper

Disadvantages

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
Advantages

Saturated colors

True 24-bit color at each pixel

Disadvantages

Expensive

Expensive to use

Wasteful of supplies

Slow

Printers - Dye Sublimation
  • Work by evaporating dyes from donor sheets onto paper
slide13

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