Function edgeTrackingHysteresis

src/backend/cuda/kernel/canny.hpp:51–93

template<typename T>
void edgeTrackingHysteresis(Param<T> output, CParam<T> strong, CParam<T> weak) {
    auto initEdgeOut = common::getKernel(
        "arrayfire::cuda::initEdgeOut", {{canny_cuh_src}},
        TemplateArgs(TemplateTypename<T>()),
        {{DefineValue(STRONG), DefineValue(WEAK), DefineValue(NOEDGE),
          DefineValue(THREADS_X), DefineValue(THREADS_Y)}});
    auto edgeTrack = common::getKernel(
        "arrayfire::cuda::edgeTrack", {{canny_cuh_src}},
        TemplateArgs(TemplateTypename<T>()),
        {{DefineValue(STRONG), DefineValue(WEAK), DefineValue(NOEDGE),
          DefineValue(THREADS_X), DefineValue(THREADS_Y)}});
    auto suppressLeftOver = common::getKernel(
        "arrayfire::cuda::suppressLeftOver", {{canny_cuh_src}},
        TemplateArgs(TemplateTypename<T>()),
        {{DefineValue(STRONG), DefineValue(WEAK), DefineValue(NOEDGE),
          DefineValue(THREADS_X), DefineValue(THREADS_Y)}});

    dim3 threads(kernel::THREADS_X, kernel::THREADS_Y);

    // Launch only threads to process non-border pixels
    int blk_x = divup(weak.dims[0] - 2, threads.x);
    int blk_y = divup(weak.dims[1] - 2, threads.y);

    // launch batch * blk_x blocks along x dimension
    dim3 blocks(blk_x * weak.dims[2], blk_y * weak.dims[3]);

    EnqueueArgs qArgs(blocks, threads, getActiveStream());
    initEdgeOut(qArgs, output, strong, weak, blk_x, blk_y);
    POST_LAUNCH_CHECK();

    auto flagPtr = edgeTrack.getDevPtr("hasChanged");

    int notFinished = 1;
    while (notFinished) {
        notFinished = 0;
        edgeTrack.setFlag(flagPtr, &notFinished);
        edgeTrack(qArgs, output, blk_x, blk_y);
        POST_LAUNCH_CHECK();
        notFinished = edgeTrack.getFlag(flagPtr);
    }
    suppressLeftOver(qArgs, output, blk_x, blk_y);
    POST_LAUNCH_CHECK();
}
}  // namespace kernel
}  // namespace cuda
}  // namespace arrayfire