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root/ipe_artfile_utils/trunk/artfile_overview.txt
Revision: 2
Committed: Thu Nov 8 11:19:36 2018 UTC (16 months, 2 weeks ago) by daniel-marschall
Content type: text/plain
File size: 2364 byte(s)
Log Message:
Initial release to SVN

File Contents

# Content
1
2 ART FILES BY IMAGINATION PILOTS
3 Technical overview by Daniel Marschall 15 Feb 2018
4
5
6 VERSION 1.x (16-bit era, "IPE16")
7 =================================
8
9 Version 1.0 For game: "Blown Away" (1994)
10 * File signature "Art" + 20 NUL bytes
11 * Image names up to 23 characters
12 (unsure if the 23th byte must be a zero terminator)
13 * LZW implementation: GIF standard implementation
14 - variable code length between 9 and 12 bits
15 - clear code (256)
16 - end code (257)
17 * Pictures can only be 8-bit
18 * Each picture can either be LZW compressed (code "P")
19 or uncompressed (code "p", lower case)
20 * Decompressed/raw data: Top-down pixel data
21 * Attached: Optional palette (R,G,B), uncompressed.
22 (Sprites usually do not have a palette, so the game
23 will use the palette of the parent picture)
24
25 Version 1.1 For games: "Panic in the Park" (1995)
26 "Where's Waldo? At the Circus" (1995)
27 * Codes for compression/raw are now "Q" and "q" instead of
28 "P" and "p"
29 * Each picture has now a relative X- and Y-offsets for 'fine-tuning'.
30 These offsets cannot be negative, though.
31
32 VERSION 2.x (32-bit era, "IPE32")
33 =================================
34
35 Version 2.0 For games: "Where's Waldo? Exploring Geography" (1996)
36 "Eraser Turnabout" (1997)
37 "Virtual K'Nex" (1998)
38 * File signature "ART_DATA"
39 * Image names up to 8 characters;
40 no zero termination required after the 8 characters.
41 * LZW implementation by Mark R. Nelson and Shawn M. Regan
42 - variable code length between 9 and 13 bits
43 - clear code (256)
44 - end code (257)
45 * Pictures are divided into chunks. Each chunk can be compressed or
46 uncompressed. Limitations:
47 - Each compressed chunk (except the last one) must decode into
48 exactly 16382 (0x3FFE) bytes of uncompressed data.
49 - The size of the compressed data of a chunk must not exceed the
50 size of the original uncompressed data.
51 * The size of each chunk (raw or compressed) is limited
52 to max. 32767 Bytes (0x7FFF).
53 * Decompressed/raw data: Windows Bitmap (without file header);
54 therefore, theoretically every color depth/compression/etc. can be used.
55 For 8-bit pictures, the palette is included in the Bitmap.
56 * Re-using of parent palette is not possible.

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