/* The following structures define the format
 * of a Windows bitmap (bmp) graphics file.
 * This format allows 32-bit precision on the
 * values in a grayscale image, so we adopt it
 * for representing interferogram images.
 */
   struct bmp_header_ {
      unsigned short int magic;
      unsigned int fsize;
      unsigned short int reserved[2];
      unsigned int offset;
   } __attribute__((packed));

   struct dib_header_ {
      unsigned int hdrlen;
      unsigned int width;
      unsigned int height;
      unsigned short int planes;
      unsigned short int depth;
      unsigned int compression;
      unsigned int size;
      unsigned int hresol;
      unsigned int vresol;
      unsigned int ncolors;
      unsigned int nimpcolors;
   } __attribute__((packed));