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Imaging (now digital) The stately history of analog photography Leonardo da Vinci – cameras obscura – 1519 Photosensitive materials explored – 16xx – 1830 (and beyond) Daguerrotype – 1839 Wet Plate processes – 1860 First impact on public awareness of the wider world

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the stately history of analog photography
The stately history of analog photography
  • Leonardo da Vinci – cameras obscura – 1519
  • Photosensitive materials explored – 16xx – 1830 (and beyond)
  • Daguerrotype – 1839
  • Wet Plate processes – 1860
    • First impact on public awareness of the wider world
  • Color photography – 1868 (first plausible process)
  • Small cameras (Leica, Ermanox, Rolleiflex) 1914 – 1920s
  • Japanese entry into camera business – 1950s
  • Automation
    • Auto exposure – 1960-64
    • Auto focus – 1980
  • Film phaseout in favor of digital – 1990 to 2010
the pixel race
The Pixel Race
  • The roots of digital imaging – 1960s and 1970s
    • CCD and CMOS photosensors first developed (1969 CCD patent)
    • Cold War spy satellites needed to eliminate dropping film by parachute!
    • CMOS – cheaper to manufacture, lower basic quality, able to add image processing on the same chip to compensate
    • CCD – nonstandard process, more expensive (and often uses outdated facilities) higher quality, but unable to integrate
      • Quickly dominated optical astronomy
  • The transition in cameras for terrestrial use
    • 1985 introduced digital camera backs ($100K)
    • Mid 1990’s – professional and consumer cameras
    • Present status (e.g. Olympus)
      • Since 1950s still supports 22 film cameras, sells about 8 more
      • Since 1996 still supports 46 digital cameras, selling 40 more
what s inside a digital camera
What’s inside a digital camera
  • Simplest case: tethered camera
    • Fixed focus (simple lens in a threaded mount)
    • Two chips
nonstandard imagers
Nonstandard Imagers
  • Novel layouts (Fuji)
    • Conventional array has greatest resolution along the 45 degree axis. Why not tilt the array to maximize x and y resolution instead…?
    • Fuji is also exploring split cells to enhance dynamic range
  • Novel 3-color single cells (Foveon)
we re not done yet other tasks
We’re not done yet – other tasks
  • Automatic exposure
  • Automatic focus
    • Active – passive
      • Passive is dominant for digital
        • Most common scheme is contrast enhancement, based on the actual image
        • Better is phase sensitive detection, since it gives direction in which to correct
how big is digital film
How big is digital film?
  • Digital backs support astronomical pixel arrays ($20-50K)
    • 20 - 25 Mpixels and 60 x 45 mm substrate
  • Highest quality digital SLRs (Nikon, Canon at $8-10K)
    • 8, 12, 16 Mpixels and 24 x 35 mm substrate
    • “full frame” 35 mm
  • New “low end” DSLRs (Nikon D70, Canon 20D, Olympus E-1)
    • 5-8 Mpixels, “magnification factor of 1.5 (APS) to 2 (4/3)
  • Consumer digicams (use 2/3, 1/1.8, … tiny chips)
    • “prosumer” 5-8 Mpixels, non-interchangeable lens < $1000
    • “consumer” 3-5 Mpixels, point and shoot <$400
  • Lenses must shrink to match imager sizes
side effects in the mpixel race
Side Effects in the MPixel Race
  • Using whole cell for imaging gives best dynamic range, lowest noise, greatest sensitivity
    • This sacrifices video output (used in LCD viewers)
  • Drawbacks of fractional cells compensated by microlenses
  • Lens design for smaller image areas is different
    • Short back focus
    • Need to restrict angle of light
    • Wide angles become normal
where is was the quality crossover
Where is(was?) the quality crossover?
  • Goto Norm Koren’s discussion
  • www.normankoren.com
  • www.imatest.com
where can we go with this
Where can we go with this?
  • What type of image taking is a digital camera not good for? Why?
  • The relationship between image resolution and information
    • Face recognition
    • Text recognition
    • Object recognition
  • Develop a rough spec for a camera that does one of the following ON-BOARD
    • Text translation (OCR)
    • Continuous wireless upload
    • Wireless printing
    • Gesture learning and recognition (for shoot still, shoot video, stop video, etc)
    • Motion detection and alarm
    • Face learning and recognition
    • Object learning and recognition
    • Visual temperature detection and alarm

NOW let’s make the camera we need for our application:

  • Given a power supply, an imaging chip, and flash memory, what would you need to do to make your own digital camera? What additional parts will you need?