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## PowerPoint Slideshow about ' Final Project' - miach

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Presentation Transcript

High Dynamic Range

- 使真實世界場景的亮暗對比，正確呈現在影像上。
- 現今多使用不同曝光度的影像來產生HDRimage。

approach

- Reference : Paul E. Debevec , Jitendra Malik, Recovering high dynamic range radiance maps from photographs, Proceedings of the 24th annual conference on Computer graphics and interactive techniques, p.369-378, August 1997
- 這篇使用不同曝光量照片來恢復成像過程的response function，從已知response function可以將多張影像合成單一影像。

film response recovery

- film reciprocity equation
- Zij where i is a spatial index over pixels and j indexes over exposure times ∆tj, E is the irradiance.
- Assume ∫ is invertible, and taking the natural logarithm
- ;
- Define , so

- recovering g only requires recovering the finite number of values that g(z) can take since the domain of Z.
- minimize the following quadratic objective function
- Zmin and Zmax be the least and greatest pixel values (integers), N be the number of pixel locations and P be the number of photographs
- use

- introduce the additional values that g(z) can take since the domain of constraint
- introduce a weighting function w(z) to emphasize the smoothness and fitting terms toward the middle of the curve.
- Now,

- We obtain values that g(z) can take since the domain of
- we reuse the weighting function in Equation 4 to give higher weight to exposures in which the pixel’s value is closer to the middle of the response function
- Equation 4 :

result values that g(z) can take since the domain of

- Source exposure times (32, 16, 8, 4)

- Source values that g(z) can take since the domain of exposure times (2, 1, 1/2, 1/4)

- Source values that g(z) can take since the domain of exposure times (1/8, 1/16, 1/32, 1/64)

- Source values that g(z) can take since the domain of exposure times (1/128, 1/256, 1/512, 1/1024)

- Output values that g(z) can take since the domain of
- 藍色的部分為原本影像既有

programs values that g(z) can take since the domain of

- UI load(讀取資料夾內的所有影像檔) start(顯示結果)

demo values that g(z) can take since the domain of

連結

- http://www.youtube.com/watch?v=UGI6sVl9F68&feature=youtu.be

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