SFW, Seattle FilmWorks image (.sfw)
The SFW Raster image file format
Bitmap images with a SFW file extension have been created with the, by now, outdated application Seattle FilmWorks which was used for film processing. Some programs are still able to view SFW files even though files with this extension use a proprietary format. Seattle FilmWorks and PhotoWorks have been discontinued.
Technical details of SFW files
The SFW file format is actually an MGI PhotoSuite file and a raster image file. This file extension is also captured by IrfanView, Graphics Converter Pro and others.