Process of combining 3 or 5… exposures into a single HDR image

Map Branches

• Factoids
  • Tutorials in digital photography
    • HDR tutorial
  • Dynamic range
  • Eye
    • 10-14 f-stops in scene
    • Can see over 24 f-stops
  • Sensor
    • Film
      • arcane alchemy that works
    • CCD
      • Charge Coupled Device
    • CMOS
      • Complementary Metal Oxide Semiconductor
  • Bayer filter
    • Groups of 4 pixels (x,y,i)
      • 2 x green
        • luminance
        • resolution
      • 1 x red
        • colour
      • 1 x blue
        • colour
    • Interpolated to (x,y,i,c)
  • Tip
    • Don't use JPEG for saving any intermediate steps
• Capture
  • OBJECTIVE
    • Obtain set of exposures to cover the required brightness range
  • "Exposure-bracketing" Max (±2 stops)
    • 3 exposures OK
    • More if necessary (rarely)
  • Need scenes that are still for 1sec
    • Architecture
    • Landscapes
    • Interiors
  • Fixed aperture (A_v)
    • Avoid changing depth of focus!
  • Tripod or bean-bag
    • best
    • but not essential
• Assembly
  • Merge to HDR (32-bit)
    • Photomatix Pro
    • Photoshop
  • Needs special s/w
  • OBJECTIVE
    • Process of combining 3 or 5… exposures into a single HDR image
      • Impossible to display properly as is
      • Object that contains all the information
• Presentation
  • Final adjustments
    • Sharpening
    • (de-)Saturation
    • Curves
    • Levels
  • Compress HDRI to displayable brightness range
    • Spatially adaptive "tone mapping"
      • linear compression
        • ?
      • = "details enhancer"
        • √
  • OBJECTIVE
    • Steps towards a displayable or printable image
• Terminology
  • tone mapping
    • spatially adaptive intensity compression
  • image
    • result of combining exposures
  • exposure
    • single frame from camera

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