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Topic       : ATARI ST Picture formats
Author      : David Baggett/Jan K⌐upka
Version     : atari_gf.hyp 0.01 (17/09/96)
Subject     : Documentation/File formats
Nodes       : 52
Index Size  : 1328
HCP-Version : 3
Compiled on : Atari
@charset    : atarist
@lang       : 
@default    : 
@help       : 
@options    : -i -s +y +z
@width      : 75Tiny    *.TNY (any resolution)
        *.TN1 (low resolution)
        *.TN2 (medium resolution)
        *.TN3 (high resolution)

  Several people have reported sightings of mutated Tiny pictures that
do not follow the standard format, so let's be careful out there. What
is described here is the format that David Mumper's original TNYSTUFF.PRG
produces.

1 byte          resolution (same as NEO, but +3 indicates rotation
                information also follows)

If resolution > 2 {
1 byte          left and right color animation limits.  High 4 bits
                hold left (start) limit; low 4 bits hold right (end) limit
1 byte          direction and speed of color animation (negative value
                indicates left, positive indicates right, absolute value
                is delay in 1/60's of a second.
1 wordword = 2 bytes
          color rotation duration (number of iterations)
}

16 words        palette
1 wordword = 2 bytes
          number of control bytes
1 wordword = 2 bytes
          number of data words
3-10667 bytes   control bytes
1-16000 words   data words
42-32044 bytes  total

  Control byte meanings:

  For a given control byte, x:

  x < 0  Absolute value specifies the number of unique words to take
         from the data section (from 1 to 127)
  x = 0  1 wordword = 2 bytes
 is taken from the control section which  specifies the
         number of times to repeat the next data wordword = 2 bytes
 (from 128 to 32767)
  x = 1  1 wordword = 2 bytes
 is taken from the control section which  specifies
         the number of unique words to be taken from the data section
         (from 128 - 32767)
  x > 1  Specifies the number of times to repeat the next wordword = 2 bytes
 taken from
         the data section (from 2 to 127)

  Format of expanded data:

  The expanded data is not simply screen memory bitmap data;
instead, the data is divided into four sets of vertical columns.
(This results in better compression.) A column consists of one specific
wordword = 2 bytes
 taken from each scan line, going from top to bottom. For example,
column 1 consists of wordword = 2 bytes
 1 on scanline 1 followed by word 1 on scanline 2,
etc., followed by wordword = 2 bytes
 1 on scanline 200.
  The columns appear in the following order:

   1st set contains columns 1, 5,  9, 13, ..., 69, 73, 77 in order
   2nd set contains columns 2, 6, 10, 14, ..., 70, 74, 78 in order
   3rd set contains columns 3, 7, 11, 15, ..., 71, 75, 79 in order
   4th set contains columns 4, 8, 12, 16, ..., 72, 76, 80 in order

   Note that Tiny partitions the screen this way regardless of resolution;
i.e., these aren't bitplanes. For example, medium resoltion only has two
bitplanes, but Tiny still divides medium resolution pictures into four
parts.