基于opencv对图片进行base64格式的编解码

首先base64&＃xff0c;了解一下&＃xff1a;Base64就是一种基于64个可打印字符来表示二进制数据的方法。
表示二进制数&＃xff0c;所以我得先让图片转化为二进制数据&＃xff0c;然后对二进制数据进行base64编码&＃xff1b;
或者先对base64字符串进行解码&＃xff0c;然后再把二进制数据转化为图片保存或展示。

流程

• 编码
  
  1. cv::Mat图片 -> 二进制数据

bool imencode(const string& ext, InputArray img, vector& buf, const vector& params&＃61;vector())
//ext&＃xff1a; 图片后缀名&＃xff0c;如".jpg"或".png"
//img&＃xff1a; 需要进行相关操作的图片
//buf&＃xff1a; 输出二进制数据到该缓存。//params&＃xff1a;格式相关的参数
//params中的每个参数成对出现&＃xff0c;即paramId_1, paramValue_1, paramId_2, paramValue_2, … &＃xff0c;当前支持如下参数&＃xff1a;
//JPEG&＃xff1a;压缩质量 ( CV_IMWRITE_JPEG_QUALITY )&＃xff0c;从0到100&＃xff08;数值越高质量越好&＃xff09;&＃xff0c;默认值为95。
//PNG&＃xff1a; compression level ( CV_IMWRITE_PNG_COMPRESSION ) 从0到9。 数值越高&＃xff0c;文件大小越小&＃xff0c;压缩时间越长。默认值为3。
//PPM, PGM, or PBM&＃xff1a;二进制标志 ( CV_IMWRITE_PXM_BINARY )&＃xff0c;0 或 1。默认值为1。

2.二进制数据 -> base64字符串
网上有很多的 base64编解码 源码&＃xff0c;本文末会添加我使用的源码供参考。

附&＃xff1a;

/*****test.cpp*****/
#include
#include
#include
#include
#include "base64.h"
using namespace cv;
using namespace std;
void write(string encode_str);
string read(string fileName);
string encode();
Mat decode();int main() { Mat img &＃61; decode();imshow("test", img);if (waitKey(1) &＃61;&＃61; 27)return 0;system("pause");return 0;
}/***编码得到的 base64字符串 写入 “base64_str” 保存***/
void write(string encode_str)
{ofstream out;out.open("base64_str", ios::out | ios::trunc);out <}/***读取指定文件保存的 base64 字符串并返回***/
string read(string fileName)
{string base64_str;ifstream in;in.open(fileName, ios::in);in >> base64_str;cout <<"base64_str.length() &＃61; " <return base64_str;
}/***编码***/
string encode()
{string img_path("img.jpg");Mat img;img &＃61; imread(img_path);if (img.empty()){cout <<"img is empty" <return "Failed";}vector img_data;imencode(".jpg", img, img_data);string str_Encode(img_data.begin(), img_data.end());write(str_Encode);
}/***解码***/
Mat decode()
{string encode_str &＃61; read("dog.base");string decode_str;//这里可以看到&＃xff0c;我调用的第三方库支持std::string类的参数形式Base64::Decode(encode_str, &decode_str);vector img_data(decode_str.begin(), decode_str.end());Mat img &＃61; imdecode(Mat(img_data), CV_LOAD_IMAGE_COLOR);return img;
}

关于base64解码&＃xff0c;碰到一个问题&＃xff1a;
借助在线编码器&＃xff0c;将以下图片&＃xff1a;

转为base64字符串&＃xff1a;
data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGB。。。。。。。。。
如果需要解析字符串&＃xff0c;加粗部分需要删除&＃xff0c;在未删除时&＃xff0c;执行程序提示&＃xff1a;

删除后&＃xff0c;运行正常&＃xff1a;

刚刚发现csdn下载如果上传资源不能免费 0.0

/*****base64.h*****/
#ifndef BASE64_H
#define BASE64_H#include const char kBase64Alphabet[] &＃61; "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789&＃43;/";class Base64 {
public:static bool Encode(const std::string &in, std::string *out) {int i &＃61; 0, j &＃61; 0;size_t enc_len &＃61; 0;unsigned char a3[3];unsigned char a4[4];out->resize(EncodedLength(in));int input_len &＃61; in.size();std::string::const_iterator input &＃61; in.begin();while (input_len--) {a3[i&＃43;&＃43;] &＃61; *(input&＃43;&＃43;);if (i &＃61;&＃61; 3) {a3_to_a4(a4, a3);for (i &＃61; 0; i <4; i&＃43;&＃43;) {(*out)[enc_len&＃43;&＃43;] &＃61; kBase64Alphabet[a4[i]];}i &＃61; 0;}}if (i) {for (j &＃61; i; j <3; j&＃43;&＃43;) {a3[j] &＃61; &＃39;\0&＃39;;}a3_to_a4(a4, a3);for (j &＃61; 0; j 1; j&＃43;&＃43;) {(*out)[enc_len&＃43;&＃43;] &＃61; kBase64Alphabet[a4[j]];}while ((i&＃43;&＃43; <3)) {(*out)[enc_len&＃43;&＃43;] &＃61; &＃39;&＃61;&＃39;;}}return (enc_len &＃61;&＃61; out->size());}static bool Encode(const char *input, size_t input_length, char *out, size_t out_length) {int i &＃61; 0, j &＃61; 0;char *out_begin &＃61; out;unsigned char a3[3];unsigned char a4[4];size_t encoded_length &＃61; EncodedLength(input_length);if (out_length return false;while (input_length--) {a3[i&＃43;&＃43;] &＃61; *input&＃43;&＃43;;if (i &＃61;&＃61; 3) {a3_to_a4(a4, a3);for (i &＃61; 0; i <4; i&＃43;&＃43;) {*out&＃43;&＃43; &＃61; kBase64Alphabet[a4[i]];}i &＃61; 0;}}if (i) {for (j &＃61; i; j <3; j&＃43;&＃43;) {a3[j] &＃61; &＃39;\0&＃39;;}a3_to_a4(a4, a3);for (j &＃61; 0; j 1; j&＃43;&＃43;) {*out&＃43;&＃43; &＃61; kBase64Alphabet[a4[j]];}while ((i&＃43;&＃43; <3)) {*out&＃43;&＃43; &＃61; &＃39;&＃61;&＃39;;}}return (out &＃61;&＃61; (out_begin &＃43; encoded_length));}static bool Decode(const std::string &in, std::string *out) {int i &＃61; 0, j &＃61; 0;size_t dec_len &＃61; 0;unsigned char a3[3];unsigned char a4[4];int input_len &＃61; in.size();std::string::const_iterator input &＃61; in.begin();out->resize(DecodedLength(in));while (input_len--) {if (*input &＃61;&＃61; &＃39;&＃61;&＃39;) {break;}a4[i&＃43;&＃43;] &＃61; *(input&＃43;&＃43;);if (i &＃61;&＃61; 4) {for (i &＃61; 0; i <4; i&＃43;&＃43;) {a4[i] &＃61; b64_lookup(a4[i]);}a4_to_a3(a3, a4);for (i &＃61; 0; i <3; i&＃43;&＃43;) {(*out)[dec_len&＃43;&＃43;] &＃61; a3[i];}i &＃61; 0;}}if (i) {for (j &＃61; i; j <4; j&＃43;&＃43;) {a4[j] &＃61; &＃39;\0&＃39;;}for (j &＃61; 0; j <4; j&＃43;&＃43;) {a4[j] &＃61; b64_lookup(a4[j]);}a4_to_a3(a3, a4);for (j &＃61; 0; j 1; j&＃43;&＃43;) {(*out)[dec_len&＃43;&＃43;] &＃61; a3[j];}}return (dec_len &＃61;&＃61; out->size());}static bool Decode(const char *input, size_t input_length, char *out, size_t out_length) {int i &＃61; 0, j &＃61; 0;char *out_begin &＃61; out;unsigned char a3[3];unsigned char a4[4];size_t decoded_length &＃61; DecodedLength(input, input_length);if (out_length return false;while (input_length--) {if (*input &＃61;&＃61; &＃39;&＃61;&＃39;) {break;}a4[i&＃43;&＃43;] &＃61; *(input&＃43;&＃43;);if (i &＃61;&＃61; 4) {for (i &＃61; 0; i <4; i&＃43;&＃43;) {a4[i] &＃61; b64_lookup(a4[i]);}a4_to_a3(a3, a4);for (i &＃61; 0; i <3; i&＃43;&＃43;) {*out&＃43;&＃43; &＃61; a3[i];}i &＃61; 0;}}if (i) {for (j &＃61; i; j <4; j&＃43;&＃43;) {a4[j] &＃61; &＃39;\0&＃39;;}for (j &＃61; 0; j <4; j&＃43;&＃43;) {a4[j] &＃61; b64_lookup(a4[j]);}a4_to_a3(a3, a4);for (j &＃61; 0; j 1; j&＃43;&＃43;) {*out&＃43;&＃43; &＃61; a3[j];}}return (out &＃61;&＃61; (out_begin &＃43; decoded_length));}static int DecodedLength(const char *in, size_t in_length) {int numEq &＃61; 0;const char *in_end &＃61; in &＃43; in_length;while (*--in_end &＃61;&＃61; &＃39;&＃61;&＃39;) &＃43;&＃43;numEq;return ((6 * in_length) / 8) - numEq;}static int DecodedLength(const std::string &in) {int numEq &＃61; 0;int n &＃61; in.size();for (std::string::const_reverse_iterator it &＃61; in.rbegin(); *it &＃61;&＃61; &＃39;&＃61;&＃39;; &＃43;&＃43;it) {&＃43;&＃43;numEq;}return ((6 * n) / 8) - numEq;}inline static int EncodedLength(size_t length) {return (length &＃43; 2 - ((length &＃43; 2) % 3)) / 3 * 4;}inline static int EncodedLength(const std::string &in) {return EncodedLength(in.length());}inline static void StripPadding(std::string *in) {while (!in->empty() && *(in->rbegin()) &＃61;&＃61; &＃39;&＃61;&＃39;) in->resize(in->size() - 1);}private:static inline void a3_to_a4(unsigned char * a4, unsigned char * a3) {a4[0] &＃61; (a3[0] & 0xfc) >> 2;a4[1] &＃61; ((a3[0] & 0x03) <<4) &＃43; ((a3[1] & 0xf0) >> 4);a4[2] &＃61; ((a3[1] & 0x0f) <<2) &＃43; ((a3[2] & 0xc0) >> 6);a4[3] &＃61; (a3[2] & 0x3f);}static inline void a4_to_a3(unsigned char * a3, unsigned char * a4) {a3[0] &＃61; (a4[0] <<2) &＃43; ((a4[1] & 0x30) >> 4);a3[1] &＃61; ((a4[1] & 0xf) <<4) &＃43; ((a4[2] & 0x3c) >> 2);a3[2] &＃61; ((a4[2] & 0x3) <<6) &＃43; a4[3];}static inline unsigned char b64_lookup(unsigned char c) {if (c >&＃61; &＃39;A&＃39; && c <&＃61; &＃39;Z&＃39;) return c - &＃39;A&＃39;;if (c >&＃61; &＃39;a&＃39; && c <&＃61; &＃39;z&＃39;) return c - 71;if (c >&＃61; &＃39;0&＃39; && c <&＃61; &＃39;9&＃39;) return c &＃43; 4;if (c &＃61;&＃61; &＃39;&＃43;&＃39;) return 62;if (c &＃61;&＃61; &＃39;/&＃39;) return 63;return 255;}
};#endif // BASE64_H

参考:OpenCV学习笔记&＃xff08;一&＃xff09;&＃xff1a;读取、显示、保存图片