File format conversion software for Seattle FilmWorks products

Background


"Various proprietary file formats incorporating JPEG compression
 also exist.  We have little or no sympathy for the existence of
 these formats.  Indeed, one of the original reasons for
 developing this free software was to help force convergence on
 common, open format standards for JPEG files.  Don't use a
 proprietary file format!" - The Independent JPEG Group

Seattle FilmWorks (SFW) is a mail order film processor which offers the option of having your photos digitized when they are developed. Although this service is very convenient for those of us who do not want to scan the pictures by hand, SFW returns the digital pictures to you in one of two proprietary file formats. They use .sfw format if the pictures are returned on floppy disk, and .pwp format if they are to be downloaded on the Internet.

Since SFW PhotoWorks software, which reads .sfw and .pwp files, is not available for UNIX, I have written two programs which convert .sfw and .pwp files to .jpg (JFIF) format, from which SFW derived these other two formats. It is interesting to note that PhotoWorks uses code written by the Independent JPEG Group (IJG). This is done without any sort of acknowledgement, in violation of the license for the IJG software.

Neither I (the author) nor this web page are in any way affiliated with Seattle FilmWorks. Although I find it annoying that SFW decided to use a proprietary file format, I am otherwise quite pleased with the quality of service which I have received from SFW, and would recommend them.

Software

The following programs will convert Seattle FilmWorks files back to .jpg (JFIF) format. The programs sfwjpg and pwpjpg will convert .sfw and .pwp files to .jpg files. These .jpg files will be flipped in the vertical direction. To recover your images, it is recommended that you use the jpegtran program. This program is included with the Independent JPEG Group's free JPEG software, which you can find here: http://www.ijg.org/files/jpegsrc.v8c.tar.gz. The proper UNIX command line is:

jpegtran -flip vertical < input.jpg > output.jpg

To do more with your pictures, I recommend two very impressive free programs:

ImageMagick, by John Cristy, is an image viewing and manipulation package which is available for most platforms, including UNIX, VMS, Macintosh, and Microsoft Windows. Utilities included with ImageMagick can be used to flip jpeg files (with some loss of quality and/or increase in file size) if you do not want to compile jpegtran for your platform.

The Gimp, by Peter Mattis, Spencer Kimball, and many others, is a fully-featured, extensible image manipulation program with many capabilities found in similar commercial programs.

Last code update: 9 May 1999

UNIX tar file - contains all source code, documentation, Solaris and Linux binaries.

Documentation

usage.txt - how to use these programs.

details.txt - how to compile these programs, and how they work.

Source Code

sfwjpg.c - converts a .sfw file to .jpg (JFIF) format.

pwpjpg.c - extracts .jpg (JFIF) files from a .pwp file.

pwpext - Bourne shell script to extract and flip images from a .pwp file.

flipjpeg.c - does a lossless vertical inversion of a .jpg (JFIF) file. Use jpegtran instead.

Windows version - maintained by Joe Nord.

Author Info

Last modified: 3 February 2011