The source code distribution of Inlab Scheme is more or less outdated and currently under review. We will provide a revised distribution of Inlab Scheme as soon as possible - depending on our available spare time.

Inlab Scheme Release 4

This is Inlab Scheme Release 4 released as Open Source Software under GPL version 2 licensing terms.

Inlab-Scheme is an independent implementation of the algorithmic language Scheme as defined by the R4RS and the IEEE Standard 1178. In addition to the language core Inlab-Scheme has support for several features like bitmap/greymap processing, basic OCR capabilities and processing capabilities of ancient patent images CD-ROM file formats.

Inlab-Scheme can be used as a general tool for image processing, OCR or specialised optical object and pattern recognition.


  • Inlab Scheme is an independent implementation of the algorithmic language Scheme and conforms to the R4RS and the IEEE Standard 1178.
  • Inlab-Scheme 4 passes the r4rstest test incuding the tests for continuations, Scheme 4 and delay/force.
  • Pretty printing, fluid-let, dynamic-wind and syntax procedures using Inlab-Scheme syntax-lambda.
  • Bitmaps: Reading and writing TIFF (G4, single/multipage), XBM and PNG file formats, scaling, rotating, comparing, inverting, cropping, page decomposition (exploding), line drawing, greymap conversions and more.
  • Greymaps: 256 greylevel images, reading and writing PNG file formats (reads anything, writes PNG greylevel interlaced/not interlaced), scaling, cropping, conversions to and from bitmaps for further analysis and processing and more.
  • Inlab Scheme Release 4 comes with two built in graphic file format converters which convert the PATIMG patent file format (as found on the USAPat CDROM series of the US PTO) and the ST.33 patent file format (as found on the US PTO PATENTIMAGES CDROM series and the european ESPACE CDROM series) to multipage tiff without decompressing.
  • Inlab Scheme Release 4 compiles to a single binary to reduce installation to an absolute minimum.
  • Inlab Scheme scripts may be invoked directly from your shell using the ‘#!’-mechanism.


  • Learning Scheme
  • Doing homework for your CS class
  • Implementing customized OCR and visual recognition applications
  • Implementing document processing and analysis tools
  • Implementing file format conversion and document processing tools for patent documents on CDROM

MIT OCW – 6.001 Structure and Interpretation of Computer Programs

When there was only one video recommendation regarding Scheme, then it would be this one: Listen to and watch the outstanding MIT OCW 6.001 lectures.

“Structure and Interpretation of Computer Programs has been MIT’s introductory pre-professional computer science subject since 1981. It emphasizes the role of computer languages as vehicles for expressing knowledge and it presents basic principles of abstraction and modularity, together with essential techniques for designing and implementing computer languages. This course has had a worldwide impact on computer science curricula over the past two decades. The accompanying textbook by Hal Abelson, Gerald Jay Sussman, and Julie Sussman is available for purchase from the MIT Press, which also provides a freely available on-line version of the complete textbook.

These twenty video lectures by Hal Abelson and Gerald Jay Sussman are a complete presentation of the course, given in July 1986 for Hewlett-Packard employees, and professionally produced by Hewlett-Packard Television. The videos have been used extensively in corporate training at Hewlett-Packard and other companies, as well as at several universities and in MIT short courses for industry.”