gpufilter
GPU-Efficient Recursive Filtering and Summed-Area Tables
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This is an example of how to use the gaussian_cpu() function in the CPU and the gaussian_gpu() function in the GPU.
#include <ctime> #include <cstdlib> #include <iostream> #include <iomanip> #include <timer.h> #include <cpuground.h> #include <gpufilter.h> // Check computation void check_reference( const float *ref, const float *res, const int& ne, float& me, float& mre ) { mre = me = (float)0; for (int i = 0; i < ne; i++) { float a = (float)(res[i]) - ref[i]; if( a < (float)0 ) a = -a; if( ref[i] != (float)0 ) { float r = (ref[i] < (float)0) ? -ref[i] : ref[i]; float b = a / r; mre = b > mre ? b : mre; } me = a > me ? a : me; } } // Main int main(int argc, char *argv[]) { const int in_w = 1024, in_h = 1024; const float sigma = 16.f; std::cout << "[gauss] Generating random input image (" << in_w << "x" << in_h << ") ... " << std::flush; float *in_cpu = new float[in_w*in_h]; float *in_gpu = new float[in_w*in_h]; srand(time(0)); for (int i = 0; i < in_w*in_h; ++i) in_gpu[i] = in_cpu[i] = rand() / (float)RAND_MAX; std::cout << "done!\n[gauss] Applying Gaussian filter with sigma = " << sigma << "\n[gauss] Considering zero-border as initial " << "condition.\n[gauss] Computing in the CPU ... " << std::flush; std::cout << std::fixed << std::setprecision(2); { gpufilter::scoped_timer_stop sts( gpufilter::timers.cpu_add("CPU") ); gpufilter::gaussian_cpu( in_cpu, in_w, in_h, sigma ); std::cout << "done!\n[gauss] CPU Timing: " << sts.elapsed()*1000 << " ms\n"; } std::cout << "[gauss] Computing in the GPU ... " << std::flush; { gpufilter::scoped_timer_stop sts( gpufilter::timers.gpu_add("GPU") ); gpufilter::gaussian_gpu( in_gpu, in_w, in_h, sigma ); std::cout << "done!\n[gauss] GPU Timing: " << sts.elapsed()*1000 << " ms\n"; } std::cout << "[gauss] GPU Timing includes memory transfers from and to " << "the CPU\n"; std::cout << "[gauss] Checking GPU result against CPU reference\n"; float me, mre; check_reference( in_cpu, in_gpu, in_w*in_h, me, mre ); std::cout << std::scientific; std::cout << "[gauss] Maximum error: " << me << "\n"; delete [] in_cpu; delete [] in_gpu; return 0; }