安装libjpeg: sudo apt-get install libjpeg-dev
demo
#include <iostream> #include <jpeglib.h> #include <memory.h> #include <stdio.h> #include <stdlib.h> int readJpegFromFile(const char *input_filename,unsigned char * &output_buffer) { struct jpeg_decompress_struct cinfo; //jpeg压缩结构 struct jpeg_error_mgr jerr; FILE* input_file; //输入文件 JSAMPARRAY buffer; int row_width; //unsigned char * output_buffer; unsigned char * tmp=NULL; cinfo.err = jpeg_std_error(&jerr); // 打开输入文件 if((input_file=fopen(input_filename,"rb"))==NULL) { fprintf(stderr,"can't open %s ",input_filename); } // 初始化jpeg压缩结构 jpeg_create_decompress(&cinfo); // 设置数据源文件 jpeg_stdio_src(&cinfo,input_file); // 设置读取jpeg 头部 (void) jpeg_read_header(&cinfo,TRUE); // 开始解码数据 (void) jpeg_start_decompress(&cinfo); std::cout<<"输出一些图像的信息："<<std::endl; std::cout<<""<<cinfo.image_width<<std::endl; std::cout<<"height:"<<cinfo.image_height<<std::endl; std::cout<<"色彩空间："<<cinfo.jpeg_color_space<<std::endl; std::cout<<"颜色通道数:"<<cinfo.num_components<<std::endl; std::cout<<"总共字节数："<<cinfo.image_width*cinfo.image_height*cinfo.output_components<<std::endl; int bytes = cinfo.image_width*cinfo.image_height*cinfo.output_components; // 行宽度 row_width = cinfo.output_width * cinfo.output_components; // R G B R G B // 跳过头文件字节 buffer = (*cinfo.mem->alloc_sarray)((j_common_ptr)&cinfo,JPOOL_IMAGE,row_width,1); output_buffer=(unsigned char*)malloc(row_width*cinfo.output_height); // 初始化为0 memset(output_buffer,0,row_width*cinfo.output_height); tmp = output_buffer; // 读取数据 行扫描 while(cinfo.output_scanline<cinfo.output_height) { (void)jpeg_read_scanlines(&cinfo,buffer,1); memcpy(tmp,*buffer,row_width); tmp+=row_width; } (void)jpeg_finish_decompress(&cinfo); // 关闭文件 fclose(input_file); return bytes; } int main() { std::cout << "Hello, World!" << std::endl; unsigned char *imgdata=NULL; readJpegFromFile("7.jpg",imgdata); printf("地址:%p ",&imgdata); if(imgdata!=NULL) { free(imgdata); } return 0; }