Alias PIX

File Format
Name	Alias PIX
Ontology	Electronic File Formats Graphics Alias PIX ; ; ;
Extension(s)	.img, .pix, .als, others
PRONOM	fmt/1092
Wikidata ID	Q28205670, Q30311736

Alias PIX is a raster image file format. It contains a 24-bit "true color" image, compressed with run-length encoding.

For practical purposes, it is identical to Vivid IMG format, though there might be a small difference in how the unimportant fields are defined.

There is also a (rare?) 8-bit single-sample variant, which might technically be called "Matte" format, instead of "PIX".

Disambiguation

Not to be confused with RLA. PIX and RLA are different formats that are both related to the terms "Alias" and "Wavefront".

An Alias PIX file has a 10 byte header, followed by the pixel data.

Robust identification of an Alias PIX file from its contents is challenging.

The field at offset 8 is 24 (00 18), or 8 for Matte format.

The field at offset 4 (x-offset) is almost always 0.

The field at offset 6 (y-offset) is almost always 0, or one less than the height, or equal to the height.

Other tests could be to check that the dimensions seem sane, or to decompress part of the image and check for errors.