操作jepg

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.26)
+project(Binarization)
+
+set(CMAKE_CXX_STANDARD 17)
+
+add_executable(Binarization main.cpp)

main.cpp

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+#include <iostream>
+#include <fstream>
+#include <list>
+
+int main() {
+    std::fstream jpg_in;
+    jpg_in.open("/Users/dongl/code/Binarization/WechatIMG7.jpg", std::ios::in);
+    if (!jpg_in.is_open()) {
+        perror("jpg 打开失败");
+    }
+
+    // 校验是否是jpg文件
+    char file_header[2] = {0};
+    // ARM 小端字节序 jpg标识头是0xffd8  所以小端0xd8ff
+    uint16_t jpg_header = 0xd8ff;
+    // 读取标识头 n-1 个字读  3-1=2
+    jpg_in.get(file_header, 3);
+    if (memcmp(file_header, &jpg_header, 2) == 0) {
+        printf("FFD8  是jpg\n");
+    }
+
+    std::list<std::string> application_segments;
+    std::list<std::string> dqt_segments;
+    std::list<std::string> frame_segments;
+    std::list<std::string> huffman_segments;
+    std::list<std::string> scan_segments;
+    std::string segments_buf = "";
+    char key_marker = 0xFF;       // 关键头
+    char head_marker = 0xD8;      // 文件头
+    char app_marker = 0xE0;       // app段
+    char dqt_marker = 0xDB;       // 定义量化头
+    char frame_marker = 0xC0;     // 帧段
+    char huffman_marker = 0xC4;   // huffman表
+    char scan_marker = 0xDA;      // 扫描段
+    char foot_marker = 0xD9;      // 文件尾
+    //RSTn (Restart Marker)：0xFFD0 至 0xFFD7，表示重启标记，用于在解码过程中进行数据恢复。
+    //APPn (Application Segment n)：0xFFE1 至 0xFFEF，表示其他应用段，可以用于存储各种应用程序或设备的相关信息。
+
+    char buf[1024] = {0};
+    jpg_in.get(buf, sizeof(buf));
+    char FFE0[2];
+    uint16_t tmp1;
+    memcpy(&FFE0, &buf, 2);
+    memcpy(&tmp1, &FFE0, 2);
+
+    while (jpg_in.get(buf, sizeof(buf))) {
+        // 读取取出来的文件缓存
+        for (const auto &item: buf) {
+            // 查看是不是新的段
+            if (item == key_marker && segments_buf != "") {
+                // 添加段
+                // 添加应用段
+                if (segments_buf[1] == app_marker)
+                    application_segments.push_back(segments_buf);
+                // 定义量化表
+                else if(segments_buf[1] == dqt_marker)
+                    dqt_segments.push_back(segments_buf);
+                // 添加帧段
+                if (segments_buf[1] == frame_marker)
+                    frame_segments.push_back(segments_buf);
+                // huffman段
+                if (segments_buf[1] == huffman_marker)
+                    huffman_segments.push_back(segments_buf);
+                // 添加扫描段
+                else if(segments_buf[1] == scan_marker)
+                    scan_segments.push_back(segments_buf);
+
+                // 文件尾
+                else if(segments_buf[1] == foot_marker) {
+                    segments_buf = "";
+                    break;
+                }
+                segments_buf = "";
+            }
+            // 添加到段缓存
+            segments_buf.push_back(item);
+        }
+    }
+
+    std::fstream segments_out;
+    segments_out.open("/Users/dongl/code/Binarization/jpg_segments_out.txt",
+                      std::ios::out | std::ios::ate);
+    if (!segments_out.is_open()) {
+        perror("jpg_segments_out 打开失败");
+    }
+
+    segments_out << "application_segments:\n";
+    for (const auto &segments: application_segments) {
+        segments_out << segments;
+        segments_out << "\n";
+    }
+
+    segments_out << "dqt_segments:\n";
+    for (const auto &segments: dqt_segments) {
+        segments_out << segments;
+        segments_out << "\n";
+    }
+
+    segments_out << "frame_segments:\n";
+    for (const auto &segments: frame_segments) {
+        uint16_t tmp;
+        uint16_t frame_size;
+        memcpy(&tmp, segments.c_str()+2, 2);
+        memcpy(&frame_size, &tmp, 2);
+        segments_out << "frame_size: " << frame_size << "\n";
+    }
+
+    segments_out << "huffman_segments:\n";
+    for (const auto &segments: huffman_segments) {
+        segments_out << segments;
+        segments_out << "\n";
+    }
+
+    segments_out << "scan_segments:\n";
+    for (const auto &segments: scan_segments) {
+        segments_out << segments;
+        segments_out << "\n";
+    }
+
+    segments_out.close();
+    jpg_in.close();
+    return 0;
+}

test.txt

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+<EFBFBD>ﾘ