Figure 4.

Parallel implementation for evaluating the corrected spectral distribution. Each band is evaluated by a block of $\sqrt{w}\mathit{\text{x}}\sqrt{w}$ threads. (a) Each block iterates across the spatial dimensions of the image from i=0 to i=n, where $n=\frac{S_x{S}_y}{w}$ and S_x and S_y are the spatial extents. The threads for i=14 (*) are shown. (b) The threads are evaluated using SIMD and kept spatially coherent to take advantage of 2D texture caching. (c) Each band is evaluated by an independent thread block and each thread performs a maximum of 3 texture fetches per iteration (1 data point and 2 baseline points). (d) Resulting histogram.