OpenCV代码提取:flip函数的实现
OpenCV中实现图像翻转的函数flip,公式为:
目前fbc_cv库中也实现了flip函数,支持多通道,uchar和float两种数据类型,经测试,与OpenCV3.1结果完全一致。
实现代码flip.hpp:
- // fbc_cv is free software and uses the same licence as OpenCV
- // Email: fengbingchun@163.com
- #ifndef FBC_CV_FLIP_HPP_
- #define FBC_CV_FLIP_HPP_
- /* reference: include/opencv2/core.hpp
- modules/core/src/copy.cpp
- */
- #include <typeinfo>
- #include "core/mat.hpp"
- namespace fbc {
- template<typename _Tp, int chs> static int flipHoriz(const Mat_<_Tp, chs>& src, Mat_<_Tp, chs>& dst);
- template<typename _Tp, int chs> static int flipVert(const Mat_<_Tp, chs>& src, Mat_<_Tp, chs>& dst);
- // Flips a 2D array around vertical, horizontal, or both axes
- // flipCode: 0 means flipping around the x - axis and positive value means flipping around y - axis.
- // Negative value means flipping around both axes
- // support type: uchar/float, multi-channels
- template <typename _Tp, int chs>
- int flip(const Mat_<_Tp, chs>& src, Mat_<_Tp, chs>& dst, int flipCode)
- {
- FBC_Assert(typeid(uchar).name() == typeid(_Tp).name() || typeid(float).name() == typeid(_Tp).name()); // uchar || float
- if (dst.empty()) {
- dst = Mat_<_Tp, chs>(src.rows, src.cols);
- } else {
- FBC_Assert(src.rows == dst.rows && src.cols == dst.cols);
- }
- Size size = src.size();
- if (flipCode < 0) {
- if (size.width == 1)
- flipCode = 0;
- if (size.height == 1)
- flipCode = 1;
- }
- if ((size.width == 1 && flipCode > 0) ||
- (size.height == 1 && flipCode == 0) ||
- (size.height == 1 && size.width == 1 && flipCode < 0)) {
- src.copyTo(dst);
- return 0;
- }
- if (flipCode <= 0)
- flipVert(src, dst);
- else
- flipHoriz(src, dst);
- if (flipCode < 0)
- flipHoriz(dst, dst);
- return 0;
- }
- template<typename _Tp, int chs>
- static int flipHoriz(const Mat_<_Tp, chs>& src, Mat_<_Tp, chs>& dst)
- {
- Size size = src.size();
- size_t esz = sizeof(_Tp) * chs;
- int i, j, limit = (int)(((size.width + 1) / 2) *esz );
- AutoBuffer<int> _tab(size.width * esz);
- int* tab = _tab;
- size_t sstep = src.step;
- size_t dstep = dst.step;
- const uchar* src_ = src.ptr();
- uchar* dst_ = dst.ptr();
- for (i = 0; i < size.width; i++) {
- for (size_t k = 0; k < esz; k++) {
- tab[i*esz + k] = (int)((size.width - i - 1) * esz + k);
- }
- }
- for (; size.height--; src_ += sstep, dst_ += dstep) {
- for (i = 0; i < limit; i++) {
- j = tab[i];
- uchar t0 = src_[i], t1 = src_[j];
- dst_[i] = t1; dst_[j] = t0;
- }
- }
- return 0;
- }
- template<typename _Tp, int chs>
- static int flipVert(const Mat_<_Tp, chs>& src, Mat_<_Tp, chs>& dst)
- {
- const uchar* src0 = src.ptr();
- uchar* dst0 = dst.ptr();
- Size size = src.size();
- size_t sstep = src.step;
- size_t dstep = dst.step;
- size_t esz = sizeof(_Tp) * chs;
- const uchar* src1 = src0 + (size.height - 1)*sstep;
- uchar* dst1 = dst0 + (size.height - 1)*dstep;
- size.width *= (int)esz;
- for (int y = 0; y < (size.height + 1) / 2; y++, src0 += sstep, src1 -= sstep, dst0 += dstep, dst1 -= dstep) {
- int i = 0;
- if (((size_t)src0 | (size_t)dst0 | (size_t)src1 | (size_t)dst1) % sizeof(int) == 0) {
- for (; i <= size.width - 16; i += 16) {
- int t0 = ((int*)(src0 + i))[0];
- int t1 = ((int*)(src1 + i))[0];
- ((int*)(dst0 + i))[0] = t1;
- ((int*)(dst1 + i))[0] = t0;
- t0 = ((int*)(src0 + i))[1];
- t1 = ((int*)(src1 + i))[1];
- ((int*)(dst0 + i))[1] = t1;
- ((int*)(dst1 + i))[1] = t0;
- t0 = ((int*)(src0 + i))[2];
- t1 = ((int*)(src1 + i))[2];
- ((int*)(dst0 + i))[2] = t1;
- ((int*)(dst1 + i))[2] = t0;
- t0 = ((int*)(src0 + i))[3];
- t1 = ((int*)(src1 + i))[3];
- ((int*)(dst0 + i))[3] = t1;
- ((int*)(dst1 + i))[3] = t0;
- }
- for (; i <= size.width - 4; i += 4) {
- int t0 = ((int*)(src0 + i))[0];
- int t1 = ((int*)(src1 + i))[0];
- ((int*)(dst0 + i))[0] = t1;
- ((int*)(dst1 + i))[0] = t0;
- }
- }
- for (; i < size.width; i++) {
- uchar t0 = src0[i];
- uchar t1 = src1[i];
- dst0[i] = t1;
- dst1[i] = t0;
- }
- }
- return 0;
- }
- } // namespace fbc
- #endif // FBC_CV_FLIP_HPP_
测试代码test_flip.cpp:
- #include "test_flip.hpp"
- #include <assert.h>
- #include <iostream>
- #include <string>
- #include <flip.hpp>
- #include <opencv2/opencv.hpp>
- int test_flip_uchar()
- {
- cv::Mat matSrc = cv::imread("E:/GitCode/OpenCV_Test/test_images/1.jpg", 1);
- if (!matSrc.data) {
- std::cout << "read image fail" << std::endl;
- return -1;
- }
- int width = matSrc.cols;
- int height = matSrc.rows;
- int flipCode[3] {-1, 0, 1}; // both axes, x axis, y axis
- for (int i = 0; i < 3; i++) {
- fbc::Mat_<uchar, 3> mat1(height, width, matSrc.data);
- fbc::Mat_<uchar, 3> mat2(height, width);
- fbc::flip(mat1, mat2, flipCode[i]);
- cv::Mat mat1_(height, width, CV_8UC3, matSrc.data);
- cv::Mat mat2_;
- cv::flip(mat1_, mat2_, flipCode[i]);
- assert(mat2.rows == mat2_.rows && mat2.cols == mat2_.cols && mat2.step == mat2_.step);
- for (int y = 0; y < mat2.rows; y++) {
- const fbc::uchar* p1 = mat2.ptr(y);
- const uchar* p2 = mat2_.ptr(y);
- for (int x = 0; x < mat2.step; x++) {
- assert(p1[x] == p2[x]);
- }
- }
- std::string name = std::to_string(i);
- std::string file_path = "E:/GitCode/OpenCV_Test/test_images/";
- std::string name_fbc = file_path + "flip_fbc_" + name + ".jpg";
- std::string name_cv = file_path + "flip_cv_" + name + ".jpg";
- cv::Mat matSave(height, width, CV_8UC3, mat2.data);
- cv::imwrite(name_fbc, matSave);
- cv::imwrite(name_cv, mat2_);
- }
- return 0;
- }
- int test_flip_float()
- {
- cv::Mat matSrc = cv::imread("E:/GitCode/OpenCV_Test/test_images/1.jpg", 1);
- if (!matSrc.data) {
- std::cout << "read image fail" << std::endl;
- return -1;
- }
- cv::cvtColor(matSrc, matSrc, CV_BGR2GRAY);
- matSrc.convertTo(matSrc, CV_32FC1);
- int width = matSrc.cols;
- int height = matSrc.rows;
- int flipCode[3] {-1, 0, 1}; // both axes, x axis, y axis
- for (int i = 0; i < 3; i++) {
- fbc::Mat_<float, 1> mat1(height, width, matSrc.data);
- fbc::Mat_<float, 1> mat2(height, width);
- fbc::flip(mat1, mat2, flipCode[i]);
- cv::Mat mat1_(height, width, CV_32FC1, matSrc.data);
- cv::Mat mat2_;
- cv::flip(mat1_, mat2_, flipCode[i]);
- assert(mat2.rows == mat2_.rows && mat2.cols == mat2_.cols && mat2.step == mat2_.step);
- for (int y = 0; y < mat2.rows; y++) {
- const fbc::uchar* p1 = mat2.ptr(y);
- const uchar* p2 = mat2_.ptr(y);
- for (int x = 0; x < mat2.step; x++) {
- assert(p1[x] == p2[x]);
- }
- }
- }
- return 0;
- }
GitHub:https://github.com/fengbingchun/OpenCV_Test
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