The method of realizing BMP transform JPG by C language _c language

This article describes the C language implementation of BMP conversion JPG method. Share to everyone for your reference. The implementation method is as follows:

/**************************************************************************** Name: jpeg.c function: Linux under BMP conversion to the JPEG program source code Date: 2010.01.26 Note: Compile-time plus "-ljpeg" (Gcc-o bmp2jpg jpeg.c-ljpeg) ******************************************************** /#include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/ioctl.h> #include <sys/mman.h> #include <linux/videodev.h> #include <fcntl.h> #include
<unistd.h> #include <stdio.h> #include <errno.h> #include <stdlib.h> #include <signal.h> #include <sys/timeb.h> #include <jpeglib.h> #define JPEG_QUALITY 95//Picture quality int bmp2jpg (const char *bmp_file, C
  Onst char *jeg_file, const int width, const int height) {file *fd;
  int ret;
  unsigned char *data;
  Long Sizeimage;
  int depth = 3;
  Jsamprow * Row_pointer;
  Long Rgb_index = 0;
  int i=0;
  struct Jpeg_compress_struct cinfo;
  struct Jpeg_error_mgr jerr;         FILE *outfile;   
  ;
  Read BMP image Data Sizeimage = width*height*3;
  data = (unsigned char*) malloc (sizeimage);
  FD = fopen (Bmp_file, "RB");
    if (!FD) {printf ("Error1:can not open the image.\n");
    Free (data);
  return-1; 
  } fseek (fd, si, seek_set);
  RET = fread (data, sizeof (unsigned char) *sizeimage, 1, FD);
      if (ret = 0) {if (ferror (FD)) {printf ("\nerror2:can not read the pixel data.\n");
      Free (data);
      Fclose (FD);
    return-1;
  }//convert BMP to JPG cinfo.err = Jpeg_std_error (&jerr);
  * Now we can initialize the JPEG compression object.
  Jpeg_create_compress (&cinfo);
    if (outfile = fopen (Jeg_file, "wb") = = NULL) {fprintf (stderr, "can ' t open%s\n", jeg_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);
   Now your can set any Non-default parameters you wish to. Here we are just illustrate the use of quality (quantization table) scaling:jpeg_set_quality (&cinfo, jpeg_quality, TR
  UE);
  * Limit to Baseline-jpeg values jpeg_start_compress (&cinfo, TRUE);
  write int j=0 once;
  Row_pointer = malloc (height*width*3);
  char * line[300];
    for (i=0;i 

I hope this article will help you with your C language program.