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Final Project

Final Project. 601410058 黃啟承. 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 HDR image 。. approach.

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Final Project

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  1. Final Project 601410058 黃啟承

  2. 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。

  3. 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。

  4. 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

  5. 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

  6. introduce the additional constraint • introduce a weighting function w(z) to emphasize the smoothness and fitting terms toward the middle of the curve. • Now,

  7. We obtain • 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 :

  8. result • Source exposure times (32, 16, 8, 4)

  9. Source exposure times (2, 1, 1/2, 1/4)

  10. Source exposure times (1/8, 1/16, 1/32, 1/64)

  11. Source exposure times (1/128, 1/256, 1/512, 1/1024)

  12. Output • 藍色的部分為原本影像既有

  13. programs • UI load(讀取資料夾內的所有影像檔) start(顯示結果)

  14. demo 連結 • http://www.youtube.com/watch?v=UGI6sVl9F68&feature=youtu.be

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