Fastgraph Pixel Run Format
Fastgraph Pixel Run Format and Fastgraph Packed Pixel Run Format are raster graphics formats associated with the Fastgraph and Fastgraph/Light graphics toolkits from Ted Gruber Software. In this article, we'll use the abbreviation PRF to refer to the formats.
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Discussion
The preferred filename extensions seem to be .SPR (probably for Standard Pixel Run) and .PPR, though others are also used.
Though the product is named "Fastgraph", some filenames use the string "FASTGRAF".
PRF is mainly for programmers. The Fastgraph package does include some DOS utilities (SNAPSHOT.EXE, CLIP.EXE, etc.) that use it.
Format details
The PRF formats are raw bitmap formats, albeit compressed. They generally require external information in order to decode them usefully. The entire file consists of compressed image data. The rows are ordered from bottom up.
It is possible for an encoder to make a file more portable by stashing extra data in it, using run counts of 0.
Pixel Run Format: 8 bits per pixel. The file consists of pairs of bytes. The first byte of a pair is the color value, and the second is the repeat count.
Packed Pixel Run Format: 4 bits per pixel. The file consists of triplets of bytes. The first byte of three contains two color values, the second is the repeat count for one of the colors, and the third is the repeat count for the other color.
Identification
There's no good way to identify an SPR or PPR file based on its contents.
However, there is a profile of SPR, apparently associated with IMPROCES, which starts with a 16-byte signature: (hex) bytes 46 00 41 00 53 00 54 00 47 00 52 00 41 00 46 00.
There is also an identifiable profile of PPR used by Young Picasso.
Software
- Fastgraph/Light [1991-05-31]: part 1, 2, 3
- Fastgraph/Light [1991-10-05]: part 1, 2, 3
- IMPROCES (v2.0+) - Image processing software for DOS that supports PRF
Sample files
- dexvert samples — image/fastgraphPRF
- fgl105c.zip → CORAL.*
- fgdemo10.zip → CASINO.PPR
- fg_xmas.zip → XMAS.PPR
- ADDALOTM.ZIP → ADDALOTM.002 (LHA/LHarc self-extracting archive) → *.prf
