Photographic Tone Reproduction for Digital Images Paper by: Erik - - PowerPoint PPT Presentation

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Photographic Tone Reproduction for Digital Images Paper by: Erik - - PowerPoint PPT Presentation

Jan 03, 2023 124 likes •406 views

Photographic Tone Reproduction for Digital Images Paper by: Erik Reinhard, Michael Stark, Peter Shirley, and James Ferwerda Tone Reproduction Problem How should we map measured/simulated scene luminances to display luminances and produce a

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Photographic Tone Reproduction for Digital Images

Paper by: Erik Reinhard, Michael Stark, Peter Shirley, and James Ferwerda

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Tone Reproduction Problem

How should we map measured/simulated scene luminances to display luminances and produce a satisfactory image?

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Key Ideas

  • Zone
  • Middle-grey
  • Dynamic range
  • Key
  • Dodging-and-

burning

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Algorithm

  • Apply luminance mapping
  • If necessary, apply automatic dodging-

and-burning

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Initial Luminance Mapping

  • r
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Automatic Dodging-and-burning

Seek first scale sm where:

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Global vs. Local operator

  • r

Global Local

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Results

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Discussion

Questions?

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Question 1

What is problematic in the algorithm?

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Question 1

What is problematic in the algorithm?

 Set parameters

“Sharpening” Phi

Scale alpha_1, alpha_2

Threshold epsilon

Scale s

Key value a

 “Magic”

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Question 2

Why does equation 9 increase local contrast?

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Question 3

What do we change in the algorithm to obtain images like this?

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Question 3

What do we change in the algorithm to obtain images like this? Make histogram peak in high/low tone area → key value a

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Question 4

Why can we obtain luminance like this? L = 0.27R + 0.67G + 0.06B

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Question 4

Why can we obtain luminance like this? L = 0.27R + 0.67G + 0.06B

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Question 4

Why can we obtain luminance like this? L = 0.27R + 0.67G + 0.06B → Luminosity function (see Wikipedia) → Scotopic vs. photopic vision Scotopic, sensitivity of the

eye is mediated by rods

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Question 5

Why is it called dodging & burning? Why does burning darken the image? Why does dodging lighten it?

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Question 5

Darkroom → prints are made from negatives → negative process: more light → darker