将RGB图像数据压缩成jpg格式图片的代码实现

#include 
#define JPEG_QUALITY 100 //图片质量

int savejpg(uchar *pdata, char *jpg_file, int width, int height)
{  //分别为RGB数据，要保存的jpg文件名，图片长宽
    int depth = 3;
    JSAMPROW row_pointer[1];//指向一行图像数据的指针
    struct jpeg_compress_struct cinfo;
    struct jpeg_error_mgr jerr;
    FILE *outfile;

    cinfo.err = jpeg_std_error(&jerr);//要首先初始化错误信息
    //* Now we can initialize the JPEG compression object.
    jpeg_create_compress(&cinfo);

    if ((outfile = fopen(jpg_file, "wb")) == NULL)
    {
        fprintf(stderr, "can't open %s\n", jpg_file);
        return -1;
    }
    jpeg_stdio_dest(&cinfo, outfile);

    cinfo.image_width = width;             //* image width and height, in pixels
    cinfo.image_height = height;
    cinfo.input_components = depth;    //* # of color components per pixel
    cinfo.in_color_space = JCS_RGB;     //* colorspace of input image
    jpeg_set_defaults(&cinfo);

    jpeg_set_quality(&cinfo, JPEG_QUALITY, TRUE ); //* limit to baseline-JPEG values
    jpeg_start_compress(&cinfo, TRUE);

    int row_stride = width * 3;
    while (cinfo.next_scanline < cinfo.image_height)
           {
            row_pointer[0] = (JSAMPROW)(pdata + cinfo.next_scanline * row_stride);//一行一行数据的传，jpeg为大端数据格式
            jpeg_write_scanlines(&cinfo, row_pointer, 1);
        }

    jpeg_finish_compress(&cinfo);
    jpeg_destroy_compress(&cinfo);//这几个函数都是固定流程
    fclose(outfile);

    return 0;
}