Final Project 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 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 , August 1997Recovering high dynamic range radiance maps from photographs 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 constraint introduce a weighting function w(z) to emphasize the smoothness and fitting terms toward the middle of the curve. Now,

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 :

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

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

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

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

Output 藍色的部分為原本影像既有

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

demo 連結