FREngine creates the ImageDocument objects in memory, if the IEngine::CreateImageDocumentsInMemory property is set to TRUE.

Image opening

The Image technology subsystem license several 3rd-party technologies:

• JPEG codec: If codec allocates more then 64Mb a temporary file is created. It is quite easy to set up another limit or switch to a memory mapped file.
• JPEG2K codec: If an image is more then 64Mb in size a temporary file is created. The limit could be changed easily.
• PDF format (APDFL): If the name of a file contains characters, not from the current code page then it is copied to a temporary one before opening. The analogous behavior is possible if a password is blank. It is also known that APDFLReader could create a temporary file with fonts of a small size.
• DjVu and XPS: No information available at the moment

Document Analysis (DA)
Has no direct requests to a file system.

Recognizer
It doesn't create any temporary files except the following cases:

• User patterns are trained
• The Morphology subsystem creates temporary files for user dictionaries. It is hard to avoid it.

Synthesis
The Synthesis could cache fonts' metrics in files in a certain location.

For some standard fonts, there are the cache files in the product distribution. For other used fonts metrics' files are created on demand. To avoid the repeatable work the Synthesis saves calculated metrics for every font in a separate file in a folder defined in synthesis parameters. If a null string is passed in parameters then metrics are not cached and recalculated every time. The recalculation could take it a bit compared to the overall processing time.

Exporter
Does not create the temporary files