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Here's 'tis:

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                           ST Picture Formats
                           ------------------
                              Compiled by:
                              Dave Baggett
                         (arpanet: dmb@TIS.COM)

                   (Please report errors or additions)

                              CONTRIBUTORS
       David Brooks    Darek Mihocka    Greg Wageman    Gerry Wheeler


                        Introductory information
                        ------------------------
word    = 2 bytes
long    = 4 bytes
palette = Hardware color palette, stored as 16 words.  First word is
          color register zero (background), last word is color register
          15.  Each word has the form:

          Bit:  (MSB) 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00 (LSB)
                      -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
                       0  0  0  0  0 R2 R1 R0  0 G2 G1 G0  0 B2 B1 B0

          R2 = MSB of red intensity 
          R0 = LSB of red intensity

          G2 = MSB of green intensity
          G0 = LSB of green intensity

          B2 = MSB of blue intensity
          B0 = LSB of blue intensity

          Intensity ranges from 0 (color not present) to 7 (highest
          intensity).

          Example: { red = 7, green = 3, blue = 5 } -> 0735 (hex)


                             The Formats
                             -----------

<NEOChrome>

1 long          resolution (0 = low res, 1 = medium res, 2 = high res)
16 words        palette
12 bytes        filename ("        .   ")
1 byte          Left color animation limit (starting color number)
1 byte          Right color animation limit (ending color number)
1 byte          color rotation speed
1 byte          color rotation direction
1 word          color rotation duration (number of iterations)
18 longs        reserved for expansion
16000 words     picture data (screen memory)
-----------
32128 bytes     total


<DEGAS>

1 word          resolution (0 = low res, 1 = medium res, 2 = high res)
                Other bits may be used in the future; use a simple bit
                test rather than checking for specific word values.
16 words        palette
16000 words     picture data (screen memory)
-----------
32034 bytes     total


<DEGAS Elite (Uncompressed)>

1 word          resolution (0 = low res, 1 = medium res, 2 = high res)
                Other bits may be used in the future; use a simple bit
                test rather than checking for specific word values.
16 words        palette
16000 words     picture data (screen memory)
4 words         left color animtion limit table (starting color numbers)
4 words         right color animation limit table (ending color numbers)
4 words         animation channel direction flag (0 = left, 1 = off, 2 = right)
4 words         animation channel delay in 1/60's of a second. [0 - 128] 
-----------
32066 bytes     total


<DEGAS Elite (Compressed)>

1 word          resolution (same as Degas, but high order bit is set; 
                i.e., hex 8000 = low res, hex 8001 = medium res,
                hex 8002 = high res).  Other bits may be used in the
                future; use a simple bit test rather than checking
                for specific word values.
16 words        palette
< 32000 bytes   control bytes
4 words         left color animtion limit table (starting color numbers)
4 words         right color animation limit table (ending color numbers)
4 words         animation channel direction flag (0 = left, 1 = off, 2 = right)
4 words         animation channel delay in 1/60's of a second. [0 - 128] 
-----------
< 32066 bytes   total

Control byte meanings:

        For a given control byte, x:

        0 <= x <= 127   Use the next x + 1 bytes literally (no repetition)
        -127 <= x <= -1 Use the next byte -x + 1 times
        -128            No operation (ignore)

Compression Scheme:

   Each bit plane is compressed separately; i.e., all data for a single
bit plane appears before any data for the next bit plane.  The first bit
plane specified is the lowest order bit plane; the last bit plane to
specified is the highest order bit plane.
   To clarify:  The first data in the file will be the data for the lowest
order bit plane of scan line zero, followed by the data for the lowest order 
bit plane of scan line one, etc., until all scan lines have been specified.  
This process repeats for the next higher order bit plane (if it exists), etc., 
until all bit planes for all scan lines have been specified.


<C.O.L.R. Object Editor Mural>

16000 words     picture data (screen memory)
                (palettes are stored in separate files)
-----------
32000 bytes     total


<Tiny>

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 word          color rotation duration (number of iterations)
}

1 word          number of control bytes
1 word          number of data bytes
16 words        palette
3-10667 bytes   control bytes
2-32000 bytes   data bytes
-------------
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 long is taken from the control section which specifies
                the number of times to repeat the next data word (from
                128 to 32767)
        x = 1   1 word 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 word 
                taken from the data section (from 2 to 127)
                

<Spectrum 512 (Uncompressed)>

80 words        First scan line of picture (unused) -- should be zeroes
15920 words     picture data (screen memory) for scan lines 1 through 199
9552 words      3 palettes for each scan line (the top scan line is
                not included because Spectrum 512 can't display it)
-----------
51104 bytes     total


<Spectrum 512 (Compressed)>

1 word          5350 (hex) ("SP")
1 word          0 (reserved for future use)
1 long          length of data bit map
1 long          length of color bit map
<= 32092 bytes  compressed data bit map
<= 17910 bytes  compressed color bit map
--------------
< 50014 bytes   total

Data compression:

   Compression is via a modified run length encoding (RLE) scheme.  The 
data map is stored as a sequence of records.  Each record consists of a
header byte followed by one or more data bytes.  The meaning of the header
byte is as follows:
        
        For a given header byte, x:

        0 <= x < 127    Use the next x + 1 bytes literally (no repetition)
        -128 <= x < 0   Use the next byte -x + 2 times

The data appears in the following order:

        1. Picture data, bit plane 0, scan lines 1 - 199
        2. Picture data, bit plane 1, scan lines 1 - 199
        3. Picture data, bit plane 2, scan lines 1 - 199
        4. Picture data, bit plane 3, scan lines 1 - 199

Decompression of data ends when 31840 data bytes have been used.

Color map compression:

   Each 16-word palette is compressed separately.  There are three 
palettes for each scan line (597 total).  The color map is stored as a
sequence of records.  Each record starts with a 1-word bit vector which
specifies which of the 16 palette entries are included in the data 
following the bit vector (1 = included, 0 = not included; i.e., stays
the same).  The least significant bit of the bit vector refers to 
palette entry zero, while the most significant bit refers to palette
entry 15.  Bit 15 must be zero, since Spectrum 512 does not use palette
entry 15.  Bit 0 should also be zero, since Spectrum 512 always makes the
background color black.  
   The words specifying the values for the palette entries indicated in
the bit vector follow the bit vector itself, in order (0 - 15).


(Version of Fri Jul 22)
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