C语言实现BMP转换JPG的方法

本文实例讲述了C语言实现BMP转换JPG的方法。分享给大家供大家参考。具体实现方法如下：

#include 
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#define JPEG_QUALITY 95 //图片质量
int Bmp2Jpg(const char *bmp_file, const 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, 54, 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 %sn", 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 you can set any non-default parameters you wish to.
   //Here we just illustrate the use of quality (quantization table) scaling:
  jpeg_set_quality(&cinfo, JPEG_QUALITY, TRUE );
  //* limit to baseline-JPEG values
  jpeg_start_compress(&cinfo, TRUE);
  //一次写入
  int j=0;
  row_pointer = malloc(height*width*3);
  char * line[300];
  for(i=0;i

希望本文所述对大家的C语言程序设计有所帮助。