I have a media library containing 500 images. I need to make some modifications to these images in Photoshop (batch resizing and color correction). I'm looking for a way to simply overwrite the files in the 'wp-content/uploads' directory without having to re-upload them via the media library. The file names will stay the same. I also want to be able to retain the title, alt, caption and description associated with the old image files.
What would be the most efficient way of going about this?