Automatically include and/or exclude files from the set directory(ies) by: name, type, color space, date modified, size, exif information, tag/comment.
By placing this Action in the beginning of the List you can include/exclude or images, but by placing it once or multiple times among the List, you can limit certain Actions to certain files even after they were processed by other Actions. For example you can adjust the brightness to all files but limit the resizing to only the jpeg files.
The idea could be extended to allow for arbitrary conditions to be evaluated not just those envisaged by the creator of the action type.
For instance this could be linked to the external actions idea so that decisions could be made on the basis not only of of any feature of the current image but also on the results of processing it and the values of any of the internal variables.
Another possibilty would be to allow the user to provide arbitrary Python expressions to be evaluated.
The use case for this is the same as that for external actions: the user encounters a need to make a decision or transformation of a type not envisaged by the programmer of the application.