#include "Halide.h"
using namespace Halide;
// Support code for loading pngs.
#include "halide_image_io.h"
using namespace Halide::Tools;
int main() {
#if 0
/*
* blur
*/
// method 1: using boundary conditions
{
Var x("x"), y("y"), c("c");
Buffer<uint8_t> input = load_image("images/rgb.ppm");
// Upgrade it to 16-bit, so we can do math without it overflowing.
Func input_16("input_16");
input_16(x, y, c) = cast<float>(input(x, y, c));
// Blur it horizontally:
Func blur_x("blur_x");
blur_x(x, y, c) = (input_16(x - 1, y, c) +
input_16(x, y, c) +
input_16(x + 1, y, c)) / 3.0f;
// Blur it vertically:
Func blur_y("blur_y");
blur_y(x, y, c) = (blur_x(x, y - 1, c) +
blur_x(x, y, c) +
blur_x(x, y + 1, c)) / 3.0f;
// Convert back to 8-bit.
Func output("output");
output(x, y, c) = cast<uint8_t>(blur_y(x, y, c));
// !!! use clipped area, instead of clamp()
// 越界了，不能这么用： Buffer<uint8_t> result = output.realize({input.width(), input.height(), 3});
Buffer<uint8_t> result(input.width() - 2, input.height() - 2, 3);
result.set_min(1, 1);
output.realize(result);
save_image(result, "blur_1.ppm");
}
// method 2: using clamped function
{
Var x("x"), y("y"), c("c");
Buffer<uint8_t> input = load_image("images/rgb.ppm");
Func clamped;
Expr x_clamped = clamp(x, 0, input.width() - 1);
Expr y_clamped = clamp(y, 0, input.height() - 1);
clamped(x, y, c) = input(x_clamped, y_clamped, c);
// Upgrade it to 16-bit, so we can do math without it overflowing.
Func input_16("input_16");
input_16(x, y, c) = cast<float>(clamped(x, y, c));
// Blur it horizontally:
Func blur_x("blur_x");
blur_x(x, y, c) = (input_16(x - 1, y, c) +
input_16(x, y, c) +
input_16(x + 1, y, c)) / 3.0f;
// Blur it vertically:
Func blur_y("blur_y");
blur_y(x, y, c) = (blur_x(x, y - 1, c) +
blur_x(x, y, c) +
blur_x(x, y + 1, c)) / 3.0f;
// Convert back to 8-bit.
Func output("output");
output(x, y, c) = cast<uint8_t>(blur_y(x, y, c));
Buffer<uint8_t> result = output.realize({input.width(), input.height(), 3});
save_image(result, "blur_2.ppm");
}
// method 3: using Halide's built-in boundary conditions
{
Var x("x"), y("y"), c("c");
Buffer<uint8_t> input = load_image("images/rgb.ppm");
Func clamped = BoundaryConditions::repeat_edge(input);
// Upgrade it to 16-bit, so we can do math without it overflowing.
Func input_16("input_16");
input_16(x, y, c) = cast<float>(clamped(x, y, c));
// Blur it horizontally:
Func blur_x("blur_x");
blur_x(x, y, c) = (input_16(x - 1, y, c) +
input_16(x, y, c) +
input_16(x + 1, y, c)) / 3.0f;
// Blur it vertically:
Func blur_y("blur_y");
blur_y(x, y, c) = (blur_x(x, y - 1, c) +
blur_x(x, y, c) +
blur_x(x, y + 1, c)) / 3.0f;
// Convert back to 8-bit.
Func output("output");
output(x, y, c) = cast<uint8_t>(blur_y(x, y, c));
Buffer<uint8_t> result = output.realize({input.width(), input.height(), 3});
save_image(result, "blur_3.ppm");
}
// method 4: use RDom for kernel offset
{
Var x("x"), y("y"), c("c");
Buffer<uint8_t> input = load_image("images/rgb.ppm");
// 边界处理
Func clamped = BoundaryConditions::repeat_edge(input);
// 提升到 float
Func input_f("input_f");
input_f(x, y, c) = cast<float>(clamped(x, y, c));
// 3×3 box blur，用 RDom 描述卷积核偏移
RDom k(-1, 3, // k.x = -1,0,1
-1, 3); // k.y = -1,0,1
Func blur("blur");
blur(x, y, c) = 0.0f;
blur(x, y, c) += input_f(x + k.x, y + k.y, c);
// 取平均 & 转回 8-bit
Func output("output");
output(x, y, c) = cast<uint8_t>(blur(x, y, c) / 9.0f);
Buffer<uint8_t> result =
output.realize({input.width(), input.height(), input.channels()});
save_image(result, "blur_4.ppm");
}
#endif
#if 0
/*
* sobel
*/
// method 1:
{
Func gx, gy, mag[3];
Var x("x"), y("y"), c("c");
Buffer<uint8_t> input = load_image("images/rgb.ppm");
Func clamped = BoundaryConditions::repeat_edge(input);
Buffer<float> Kx(3, 3);
Kx(0,0) = -1; Kx(1,0) = 0; Kx(2,0) = 1;
Kx(0,1) = -2; Kx(1,1) = 0; Kx(2,1) = 2;
Kx(0,2) = -1; Kx(1,2) = 0; Kx(2,2) = 1;
Buffer<float> Ky(3, 3);
Ky(0,0) = -1; Ky(1,0) = -2; Ky(2,0) = -1;
Ky(0,1) = 0; Ky(1,1) = 0; Ky(2,1) = 0;
Ky(0,2) = 1; Ky(1,2) = 2; Ky(2,2) = 1;
RDom r(0, 3, 0, 3);
gx(x, y, c) = 0.0f;
gx(x, y, c) += clamped(x + r.x - 1, y + r.y - 1, c) * Kx(r.x, r.y);
gy(x, y, c) = 0.0f;
gy(x, y, c) += clamped(x + r.x - 1, y + r.y - 1, c) * Ky(r.x, r.y);
// L2
mag[0](x , y, c) = sqrt(gx(x , y, c) * gx(x , y, c)
+ gy(x , y, c) * gy(x , y, c));
// L1
mag[1](x , y, c) = abs(gx(x , y, c) * gx(x , y, c))
+ abs(gy(x , y, c) * gy(x , y, c));
// L2 no sqrt
mag[2](x , y, c) = (gx(x , y, c) * gx(x , y, c))
+ (gy(x , y, c) * gy(x , y, c));
for (int i = 0; i < 3; i++) {
Func output("output");
output(x, y, c) = cast<uint8_t>(clamp(mag[i](x, y, c), 0, 255));
Buffer<uint8_t> result = output.realize({input.width(), input.height(), input.channels()});
char filename[50] = {0};
snprintf(filename, 49, "sobel_1_%d.ppm", i);
save_image(result, filename);
}
}
#endif
#if 1
{
Var x, y, c;
Buffer<uint8_t> input = load_image("images/rgb.ppm");
Func clamped = BoundaryConditions::repeat_edge(input);
Func stencil("stencil");
Expr sum =
clamped(x, y, c) +
clamped(x + 1, y, c) +
clamped(x - 1, y, c) +
clamped(x, y + 1, c) +
clamped(x, y - 1, c);
stencil(x, y, c) = cast<uint8_t>(sum / 5);
Buffer<uint8_t> result =
stencil.realize({input.width(), input.height(), input.channels()});
save_image(result, "simple_stencil.ppm");
}
#endif
return 0;
}