./plugins/imageformats/
by default) for anything that looks like an Image Format plugin and loads what ever it can.
Image Format plugins come in two types: Raw plugins and standard plugins. Raw plugins are normal image format plugins which report themselves as being able to handle raw image files. As there is generally no way of telling if any particular file is a valid raw image file, the raw plugin is expected to load what ever it is told to without attempting any validation. Because of this, raw plugins are the very last to be tried when attempting to open a disk image. Anything that does not report itself as handling raw image files (that is, all standard plugins) will be attempted first.
For the DIMG to work properly there must be at least one compatible raw plugin present in this Image Format plugin directory.