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#include <stdio.h>
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#include <time.h>
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// 原始的高斯模糊函数
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void applyGaussianBlur(float src[][5], float dst[][5], int h, int w, float kernel[3][3]) {
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for (int i = 1; i < h - 1; i++) {
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for (int j = 1; j < w - 1; j++) {
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float sum = 0.0;
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for (int ki = -1; ki <= 1; ki++) {
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for (int kj = -1; kj <= 1; kj++) {
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sum += src[i + ki][j + kj] * kernel[ki + 1][kj + 1];
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}
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}
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dst[i][j] = sum;
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}
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}
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}
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// 优化后的可分离高斯模糊函数
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void applySeparableGaussianBlur(float src[][5], float dst[][5], int h, int w, float kx[3], float ky[3]) {
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// 用于存储行内卷积的中间结果
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float buf[3][5];
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// 宏定义用于循环利用 buf 数组的 3 个行缓冲区
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#define BUF_ROW(r) buf[(r) % 3]
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// 循环计算前两行的行内卷积并存储在 buf 中
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for (int j = 1; j < w - 1; j++) {
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BUF_ROW(0)[j] = src[1][j] * kx[1] + src[1][j - 1] * kx[0] + src[1][j + 1] * kx[2];
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BUF_ROW(1)[j] = src[2][j] * kx[1] + src[2][j - 1] * kx[0] + src[2][j + 1] * kx[2];
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}
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// 每算一行新的,凑齐 3 行,做一次行间的卷积。期间更新 buf
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for (int i = 2; i < h - 1; i++) {
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for (int j = 1; j < w - 1; j++) {
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BUF_ROW(2)[j] = src[i][j] * kx[1] + src[i][j - 1] * kx[0] + src[i][j + 1] * kx[2];
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float sum = BUF_ROW(0)[j] * ky[0] + BUF_ROW(1)[j] * ky[1] + BUF_ROW(2)[j] * ky[2];
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dst[i][j] = sum;
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}
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// 更新 buf
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for (int j = 1; j < w - 1; j++) {
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BUF_ROW(0)[j] = BUF_ROW(1)[j];
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BUF_ROW(1)[j] = BUF_ROW(2)[j];
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}
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}
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}
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int main() {
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float src[5][5] = {
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{1, 2, 3, 4, 5},
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{6, 7, 8, 9, 10},
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{11, 12, 13, 14, 15},
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{16, 17, 18, 19, 20},
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{21, 22, 23, 24, 25}
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};
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float kernel[3][3] = {
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{1.0 / 16, 2.0 / 16, 1.0 / 16},
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{2.0 / 16, 4.0 / 16, 2.0 / 16},
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{1.0 / 16, 2.0 / 16, 1.0 / 16}
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};
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// 拆分 kernel 为行方向和列方向两个向量
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float kx[3] = {kernel[0][0], kernel[0][1], kernel[0][2]};
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float ky[3] = {kernel[0][0], kernel[1][0], kernel[2][0]};
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float dst1[5][5];
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float dst2[5][5];
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// 使用原始高斯模糊函数并计时
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clock_t start1 = clock();
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applyGaussianBlur(src, dst1, 5, 5, kernel);
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clock_t end1 = clock();
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double elapsedTime1 = (double)(end1 - start1) / CLOCKS_PER_SEC;
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// 使用优化后的高斯模糊函数并计时
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clock_t start2 = clock();
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applySeparableGaussianBlur(src, dst2, 5, 5, kx, ky);
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clock_t end2 = clock();
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double elapsedTime2 = (double)(end2 - start2) / CLOCKS_PER_SEC;
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// 输出原始高斯模糊结果和时间
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printf("Original Gaussian Blur Output matrix:\n");
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for (int i = 0; i < 5; i++) {
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for (int j = 0; j < 5; j++) {
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printf("%f ", dst1[i][j]);
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}
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printf("\n");
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}
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printf("Time taken by original function: %f seconds\n", elapsedTime1);
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// 输出优化后的高斯模糊结果和时间
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printf("\nOptimized Separable Gaussian Blur Output matrix:\n");
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for (int i = 0; i < 5; i++) {
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for (int j = 0; j < 5; j++) {
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printf("%f ", dst2[i][j]);
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}
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printf("\n");
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}
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printf("Time taken by optimized function: %f seconds\n", elapsedTime2);
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return 0;
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}
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