Question

solve the equation ofs^^///whdr_//krc gin detail explain​

Answer 1

Answer:

Each pixel value across all exposures can be thought of as a function of scene radiance at that point and the duration of the exposure. Because this function could a be a fairly complicated response curve, it's easier to solve for the function g: the log of f's inverse. Therefore, g maps pixel values to the log of exposure values: g(Zij)= ln(Ei) + ln(tj), for pixel i in image j, which is equation 2 in the Debevec paper. Though this is infinitely under-constrained if g is considered to be a continuous function, we must observe that we only want the output for values 0-255, which is essentially 256 different equations in a linear system. Adding a smoothness constraint to this (second derivative should be zero) and an anchor constraint (directly defining one value for g), we have an over-constrained linear system of equations which MATLAB can easily solve for us. (The formulation of this matrix equation is illustrated here.) Once we have solved for the 256 pertinent values of g, we can easily reformulate the equation above (equation 2) to determine a mapping from pixel to radiance value. Because we want to incorporate the values observed for each exposure, we take the sum of g - ln(exposure) across each different exposure. This sum is weighted to give higher relevance to exposures where a pixel's value is closer to the middle of the response function; this is equation 6 in Debevec. Solving this gives us the log of the radiance for each pixel in the scene, so after exponentiating these values the radiance map is complete