Running the halide-lang.org sample code

CMakeLists.txt

cmake_minimum_required(VERSION 3.16)
project(BlogBlur)

find_package(Halide REQUIRED)

add_executable(blur main.cpp)
target_link_libraries(blur PRIVATE Halide::Halide Halide::ImageIO)

main.cpp

#include "Halide.h"
#include "halide_image_io.h"

#include <iostream>
#include <utility>

using namespace Halide;
using namespace Halide::Tools;

Func blur3x3(Func input) {
    Func blur_x, blur_y;
    Var x, y, xi, yi;

    // The algorithm - no storage or order
    blur_x(x, y) = (input(x - 1, y) + input(x, y) + input(x + 1, y)) / 3;
    blur_y(x, y) = (blur_x(x, y - 1) + blur_x(x, y) + blur_x(x, y + 1)) / 3;

    // The schedule - defines order, locality; implies storage
    blur_y.tile(x, y, xi, yi, 256, 32).vectorize(xi, 8).parallel(y);
    blur_x.compute_at(blur_y, x).vectorize(x, 8);

    return blur_y;
}

int main(int argc, char **argv) {
    if (argc < 3) {
        std::cout << "Usage: " << argv[0] << " <input-file> <output-file>\n";
        return 1;
    }

    // 1. Load the image from disk.
    Buffer<float> input = load_and_convert_image(argv[1]);

    // 2. Define the points outside the image.
    Func with_boundary = BoundaryConditions::repeat_edge(input);

    // 3. Build the blur program.
    Func output = blur3x3(with_boundary);

    // 4. JIT compile and run the blur.
    Buffer<float> result = output.realize(input.width(), input.height());
    
    // 5. Write the code back out.
    convert_and_save_image(result, argv[2]);

    return 0;
}

parrot.png

parrot_blurred.png