Movatterモバイル変換

Network Working Group                                            A. KatzRequest for Comments: 797                                            ISI                                                          September 1981FORMAT FOR BITMAP FILES   This note describes a proposed format for storing simple bitmaps (one   bit per pixel)  in a file.   These  files  may be very  large and the   intent  is to use this format for short term storage and passing data   between  closely  coupled  programs.   The data in the file should be   stored in 8-bit bytes (octets).  Bitmaps may be any size.   The first  4 octets  of the file  gives  the width  of each  line  (x   direction),  and the next 4 octets should give the number of lines of   the display  (length, y direction). After this is one octet for the x   increment  and one octet for the y  increment.   Following  these  10   octets  is the bitmap  itself.     The length  and width  fields  are   stored most significant octet first.   The x and y increment  octets  tell how much space is between pixels.   For an ordinary display, both these would be one.   Each line of the display  should  be scanned  from left to right. The   lines should start at the top and work down.  Each line in the bitmap   should  end on an octet boundary.  If the width of the display is not   divisable  by 8,  the rest of the last octet  should  be filled  with   zeros on the right.   Below  is a representation  of a bitmap  file  (each  square  is  one   octet):      ----------------------------------------------------------      |    1     |    2     |    3     |     4     |     5     |      |  width   |  width   |  width   |   width   |  length   |      ----------------------------------------------------------      ----------------------------------------------------------      |     6    |     7    |     8    |     9     |     10    |      |  length  |  length  |  length  |x-increment|y-increment|      ----------------------------------------------------------      ----------------------------------------------------------      |   11     |   12     |   13     |    14     |   15      |  data    |  data    |  data    |   data    |  data...      ----------------------------------------------------------   For example,  bitmaps  from the RAPICOM  450 can be in  Fine  Detail,   Quality,  or Express  Mode.   In Fine Detail mode the x-increment and   y-increment  would be 1, for Quality mode, the x-increment would be 1   and the y-increment would be 2, and for Express mode, the x-incrementAlan R. Katz                                                    [page 1]

   would  be 1 and the y-increment  would be 3.  For these bitmaps it is   intended  that each scan line be repeated y-increment times when they   are displayed.[page 2]                                                    Alan R. Katz