JPEG转RGB

jpeg解码—libjpeg

在ubuntu要安装libjpeg8-dev

sudo apt install libjpeg8-dev

一、解码流程

int read_JPEG_file(const char *jpegData, char *rgbdata, int size)
{
   
    struct jpeg_error_mgr jerr;
    struct jpeg_decompress_struct cinfo;
    cinfo.err = jpeg_std_error(&jerr);
    // 1.创建解码对象并初始化
    jpeg_create_decompress(&cinfo);
    // 2.装备解码的数据
    // jpeg_stdio_src(&cinfo,infile);
    jpeg_mem_src(&cinfo, (unsigned char *)jpegData, size);
    // 3.获取jpeg图片文件的参数
    (void)jpeg_read_header(&cinfo, TRUE);
    // Step 4:set parameters for decompression
    // 5.开始解码
    (void)jpeg_start_decompress(&cinfo);
    // 6.申请存储一行数据的内存空间
    int row_stride = cinfo.output_width * cinfo.output_components;
    unsigned char *buffer = malloc(row_stride);
    int i = 0;
    while (cinfo.output_scanline < cinfo.output_height)
    {
   
        (void)jpeg_read_scanlines(&cinfo, &buffer, 1);
        memcpy(rgbdata + i * 640 * 3, buffer, row_stride);
        i++;
    }
    // 7.解码完成
    (void)jpeg_finish_decompress(&cinfo);
    // 8.释放解码对象
    jpeg_destroy_decompress(&cinfo);
    return 1;
}

二、代码实现：

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <string.h>
#include <linux/videodev2.h> //命令码
#include <sys/mman.h>
#include <jpeglib.h>
#include <linux/fb.h>

int read_JPEG_file(const char *jpegData, char *rgbdata, int size)
{
   
    struct jpeg_error_mgr jerr;
    struct