When working with image fields in custom modules the first time an image is added a preview image is created. If you update the image but not the image name, then the preview image stays cached to the first version and there seems to be no way to clear the cache other than changing the file name.
Problem caused: image field preview does not match image. Clients/developers are confused as to why the wrong image is displaying on the back end when the correct image is displaying on the front end.
Suggested resolution: Update preview image every time an image is selected even if it has the same name as the image that was previously in the field.
