gitignore and how to ignore a common directory name and its contents

I've been pulling out my hair researching the net and various docs about .gitignore files. I'm a bit of a n00b with Unix/Terminal (using Mac OS X) and I can't for the life of me figure out how to ignore a folder's contents (any kind of content, be it a file or another folder, no matter how deep it is).

I'm working on a project that generates image files within a consistent file structure, except we're getting merge conflicts regarding user permissions. I'd like to ignore the folders that contain the generated images so we can avoid any further hair-pulling having to adjust permissions on a per-pull basis. I'm just having trouble getting the .gitignore file to work, so I need to figure out the right pattern for folder's content matching. I want it to be general enough in that it can easily encompass the whole site (so if any folder contains a particular folder name, it will ignore its contents).

I've tried:

# Images
resample/
resize/
min/

And...

# Images
resample/*
resize/*
min/*

And...

# Images
*/resample/*
*/resize/*
*/min/*

And many more combinations with unsatisfactory results. I never got the foldername/**/* pattern to ever work either. Any help regarding this issue would be most appreciated!