Gradient Domain High Dynamic Range Compression

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Gradient Domain High Dynamic Range Compression

• Raanan Fattal Dani Lischinski Michael
  Werman

The Hebrew University of Jerusalem
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The Method in 1D
25001
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The Method in 2D

• Given a log-luminance image H(x,y)
• Compute an attenuation map
• Compute an attenuated gradient field G
• Problem G is not integrable!

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Solution

• Look for image I with gradient closest to G in
  the least squares sense.
• I minimizes the integral

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Solve
.. 1 1 -4 1 1 ..
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Attenuation
Gradient magnitude
log(Luminance)
Attenuation map
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Multiscale Gradient Attenuation
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Final Gradient Attenuation Map
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Performance

• Measured on 1.8 GHz Pentium 4
• 512 x 384 1.1 sec
• 1024 x 768 4.5 sec
• Can be accelerated using processor-optimized
  libraries.

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Informal comparison
BilateralDurand et al.
PhotographicReinhard et al.
Gradient domainFattal et al.
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Informal comparison
BilateralDurand et al.
PhotographicReinhard et al.
Gradient domainFattal et al.
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Formal validation
tonemapping result
HDR display
tonemapping result