example_bspline.cc

This is an example of how to use the bspline3i_cpu() function in the CPU and the bspline3i_gpu() function in the GPU.

See also:

cpuground.h

#include <ctime>
#include <cstdlib>

#include <iostream>
#include <iomanip>

#include <timer.h>

#include <gpufilter.h>

#include <cpuground.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 gpufilter::initcond ic = gpufilter::mirror;
    const int extb = 1;

    std::cout << "[bspline] 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[bspline] Applying bspline3i filter\n"
              << "[bspline] Considering mirror as initial condition.\n"
              << "[bspline] Extending CPU image ... " << std::flush;

    int ext_w, ext_h;
    float *ext_cpu;
    gpufilter::extend_image( ext_cpu, ext_w, ext_h, in_cpu, in_w, in_h,
                             extb, ic );

    std::cout << "done!\n[bspline] Computing in the CPU ... " << std::flush;

    std::cout << std::fixed << std::setprecision(2);

    {
        gpufilter::scoped_timer_stop sts( gpufilter::timers.cpu_add("CPU") );

        gpufilter::bspline3i_cpu( ext_cpu, ext_w, ext_h, 0, gpufilter::zero );

        std::cout << "done!\n[bspline] CPU Timing: " << sts.elapsed()*1000
                  << " ms\n";
    }

    std::cout << "[bspline] Computing in the GPU ... " << std::flush;

    {
        gpufilter::scoped_timer_stop sts( gpufilter::timers.gpu_add("GPU") );

        gpufilter::bspline3i_gpu( in_gpu, in_w, in_h, extb, ic );

        std::cout << "done!\n[bspline] GPU Timing: " << sts.elapsed()*1000
                  << " ms\n";
    }

    std::cout << "[bspline] GPU Timing includes memory transfers from and to "
              << "the CPU\n[bspline] Extracting CPU image ... " << std::flush;

    gpufilter::extract_image( in_cpu, in_w, in_h, ext_cpu, ext_w, extb );

    std::cout << "done!\n[bspline] 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 << "[bspline] Maximum error: " << me << "\n";

    delete [] in_cpu;
    delete [] in_gpu;

    return 0;

}