Created
May 22, 2024 18:18
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Using convolution for horizontal edge detection.
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// 5x5 image | |
const image = [ | |
[1, 2, 3, 4, 5], | |
[5, 4, 3, 2, 1], | |
[0, 2, 4, 6, 8], | |
[8, 6, 4, 2, 0], | |
[3, 4, 5, 2, 1], | |
]; | |
// seeded for horizontal edge-detection | |
const kernel_x = [ | |
[-1, 0, 1], | |
[-2, 0, 2], | |
[-1, 0, 1], | |
]; | |
type Point = { row: number, col: number }; | |
function convolve_step(image: number[][], center: Point, kernel: number[][]) { | |
return ( | |
// top | |
(image[center.row - 1]?.[center.col - 1] ?? 0) * kernel[0][0] + | |
(image[center.row - 1]?.[center.col] ?? 0) * kernel[0][1] + | |
(image[center.row - 1]?.[center.col + 1] ?? 0) * kernel[0][2] + | |
// middle | |
(image[center.row]?.[center.col - 1] ?? 0) * kernel[1][0] + | |
(image[center.row]?.[center.col] ?? 0) * kernel[1][1] + | |
(image[center.row]?.[center.col + 1] ?? 0) * kernel[1][2] + | |
// bottom | |
(image[center.row + 1]?.[center.col - 1] ?? 0) * kernel[1][0] + | |
(image[center.row + 1]?.[center.col] ?? 0) * kernel[1][1] + | |
(image[center.row + 1]?.[center.col + 1] ?? 0) * kernel[1][2] | |
); | |
} | |
const output = [ | |
[0, 0, 0, 0, 0], | |
[0, 0, 0, 0, 0], | |
[0, 0, 0, 0, 0], | |
[0, 0, 0, 0, 0], | |
[0, 0, 0, 0, 0], | |
] | |
for (let row = 0; row < 5; row += 1) { | |
for (let col = 0; col < 5; col += 1) { | |
output[row][col] = convolve_step(image, {row, col}, kernel_x); | |
} | |
} |
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