ColoRIX

File Format
Name	ColoRIX
Ontology	Electronic File Formats Graphics ColoRIX
Extension(s)	.sc?, .scf, .sci, .scr, .scx, .rix, .vmg, others
Released	≤1986

ColoRIX, or RIX, is a raster image file format associated with the ColoRIX VGA Paint and EGA Paint applications for MS-DOS, developed by RIX SoftWorks. There are at least two versions of it.

Format details

The "new" format (with "RIX3" signature) consists of a 10-byte header, then a color palette, then the image data. If the image is compressed, the high bit of the byte at offset 9 is set.

The "old" format lacks the header. If the image is compressed, the high bit of the first byte of the file is set. The low 6 bits of the first 16 bytes are an EGA-style color palette. The image data starts at offset 16.

Both old and new ColoRIX files may optionally be compressed, using a fairly complex compression scheme. The compression scheme starts by splitting the image data into one or more segments. For 256-color images only, an XOR filter is applied. Then comes run-length encoding, followed by Huffman coding. It is vaguely similar to Squeeze, though the details are different.

Identifiers

Many filename extensions have been reported or observed. Most are listed below. Extensions beginning with "SC" are generally used for full-screen images, with the third letter a code for the screen mode.

Ext.	Mode	Remarks
.RIX	?	Used generically?
.SCA	?
.SCB	?
.SCC	?
.SCD	320x200x16
.SCE	640x200x16
.SCF	640x480x256
.SCG	800x600x16
.SCI	320x200x256
.SCK	320x400x256
.SCL	640x400x256
.SCN	800x600x256
.SCO	1024x768x256
.SCP	640x480x16
.SCQ	360x480x256
.SCR	640x350x16
.SCT	640x400x16
.SCU	1024x768x16
.SCV	?
.SCW	640x350x256
.SCX	?	Seems to be used for various image sizes.
.SCY	?
.SCZ	Text mode?
.VMG	Various	Default extension for non-fullscreen images saved by VGA Paint

Identification

New (VGA Paint) format: Files begin with ASCII characters "RIX3".

Note that the VGA Paint distribution includes other files, in other formats, that also begin with "RIX", but have a different fourth byte.

Uncompressed old format: There's no robust way to identify the format, though you could check the file size (exactly 112016 bytes for SCR format), and validate the palette.

Compressed old format: There's no easy way to identify the format, though it is possible to identify it by reading the file and checking for errors.

Specifications

• RIX File Format Summary, from the Encyclopedia of Graphics File Formats
• RIX image File Format
• Picture format docs (of a number of formats including this one)
• Fallout 2 RIX File Format

Software

• ColoRIX VGA Paint 1.36 (at Internet Archive)
• RIXLATE.EXE - Format conversion utility for DOS, included with, e.g., ColoRIX VGA Paint 1.36
• Konvertor
• XnView
• GrafX2

Sample files

• VGARIX.ZIP → *.SCI
• https://telparia.com/fileFormatSamples/image/rix/
• SCF Samples
• SDN¹ Plus → demos/colorix.zip → *.SCF
• Shareware Grab Bag → 008/egaslide.arc - EGA Slide, a component of EGA Paint (?). Includes some .SCR files in an old version of the format.

The Rolex demo

Apparently, RIX SoftWorks released a "Rolex" clock demo app that loads and displays an included (old-format) RIX file.

• MS-DOS Shareware: ROLEX
• rolex.zip

And some people modified it to display a custom image. A few of these mods may be found by searching the Internet Archive Software Collection for "rix softworks" (some may be NSFW).

• Other examples (compressed): micky.zip, tiggs.zip, GARFY.ZIP, SMURF.ZIP, MEGCLOCK.ZIP
• Other examples (uncompressed): buny.zip, pinkp.zip, TWEET.ZIP, USA_1.ZIP, EMIKO1.ZIP

Links

• EGA Paint ad in PC Magazine, Mar 10, 1987, p. 287