MATLAB conv2卷積的實現

標籤：blog   http   for   2014   問題   代碼   log   amp   line   

二維卷積的演算法原理比較簡單，參考任意一本數字訊號處理的書籍，而matlab的conv2函數的濾波有個形狀參數，用下面的一張圖很能說明問題：

這裡給出本人自己的實現方案，代碼的最佳化空間很大，用到了自己目前開發的FastIV中的一些函數介面。具體實現如下：

#include "fiv_core.h"typedef enum{FIV_CONV2_SHAPE_FULL,FIV_CONV2_SHAPE_SAME,FIV_CONV2_SHAPE_VALID}FIV_CONV_SHAPE;void fIv_conv2(fIvMat** dst_mat, fIvMat* src_mat, fIvMat* kernel_mat, FIV_CONV_SHAPE shape){int src_row = src_mat->rows;int src_cols = src_mat->cols;int kernel_row = kernel_mat->rows;int kernel_cols = kernel_mat->cols;int dst_row = 0, dst_cols = 0, edge_row = 0, edge_cols = 0;int i,j, kernel_i,kernel_j,src_i,src_j;fIvMat* ptr_dst_mat = NULL;switch(shape){case FIV_CONV2_SHAPE_FULL:dst_row = src_row + kernel_row - 1;dst_cols = src_cols + kernel_cols - 1;edge_row = kernel_row - 1;edge_cols = kernel_cols - 1;break;case FIV_CONV2_SHAPE_SAME:dst_row = src_row;dst_cols = src_cols;edge_row = (kernel_row - 1) / 2;edge_cols = (kernel_cols - 1) / 2;break;case FIV_CONV2_SHAPE_VALID:dst_row = src_row - kernel_row + 1;dst_cols = src_cols - kernel_cols + 1;edge_row = edge_cols = 0;break;}ptr_dst_mat = fIv_create_mat(dst_row, dst_cols, FIV_64FC1);*dst_mat = ptr_dst_mat;for (i = 0; i < dst_row; i++) {ivf64* ptr_dst_line_i = (ivf64* )fIv_get_mat_data_at_row(ptr_dst_mat, i);for (j = 0; j < dst_cols; j++) {ivf64 sum = 0;kernel_i = kernel_row - 1 - FIV_MAX(0, edge_row - i);src_i = FIV_MAX(0, i - edge_row);for (; kernel_i >= 0 && src_i < src_row; kernel_i--, src_i++) {ivf64* ptr_src_line_i,*ptr_kernel_line_i;kernel_j = kernel_cols - 1 - FIV_MAX(0, edge_cols - j);src_j = FIV_MAX(0, j - edge_cols);ptr_src_line_i = (ivf64*)fIv_get_mat_data_at_row(src_mat, src_i);ptr_kernel_line_i = (ivf64*)fIv_get_mat_data_at_row(kernel_mat, kernel_i);ptr_src_line_i += src_j;ptr_kernel_line_i += kernel_j;for (; kernel_j >= 0 && src_j < src_cols; kernel_j--, src_j++){sum += *ptr_src_line_i++ * *ptr_kernel_line_i--;}}ptr_dst_line_i[j] = sum;}}}FIV_ALIGNED(16) ivf64 ker_data[4*4] = {0.1,0.2,0.3,0.4,   0.5,0.6,0.7,0.8,   0.9,1.0,1.1,1.2,   1.3,1.4,1.5,1.6};void test_conv2(){fIvMat* src_mat = fIv_create_mat_magic(8, FIV_64FC1); // 8x8 magic matrixfIvMat* kernel_mat = fIv_create_mat_header(4, 4, FIV_64FC1);fIvMat* dst_mat = NULL;fIv_set_mat_data(kernel_mat, ker_data, (sizeof(ivf64)) * 4 * 4);fIv_conv2(&dst_mat, src_mat, kernel_mat, FIV_CONV2_SHAPE_FULL);fIv_export_matrix_data_file(dst_mat,"dst_mat_4x4-full.txt", 1);fIv_release_mat(&src_mat);fIv_release_mat(&kernel_mat);fIv_release_mat(&dst_mat);}int main(){test_conv2();return 0;}

MATLAB conv2卷積的實現