Especially, Lossless Photo Squeezer can import the entire directory (including subdirectories) and output the images back without changing the original directory structure. It is the unique features that you don’t need spend extra time to re-organize all your photos after being optimized.

How it works?
It comes with compression capabilities which compresses and reduces large image size significantly but keep the original resolution, quality. There are three modes for your choice: Lossless mode (png, jpg, gif); Lossy mode (jpg); PNG 8 bit mode.
- Lossless mode will save space > 20% but keep the original resolution
- Lossy mode will save space > 50% with minor quality loss.
- PNG 8 bit mode which converts 24-color png to 256-color png will save space > 60%

Benefits :
- Free up valuable web space, online account space, hard drive space and so on.
- Save Network Transmission Time. It normally takes 1 hour to upload 50 pieces of high quality images to your online photo account ! Use Lossless Photo Squeezer to shrink your files and it just costs you 10 minutes only.
- Save Manpower. It is a useful tool for quickly shrinking an image to post online, rather than having to open Photoshop or other app to edit.
- Meet Email Limits. At most cases, you can only send up to 10 MB in your email as an attachment. Lossless Photo Squeezer will reduce the photo size per your quality request and send them to your friends within email limits.

Features :
- Easy to use.
- Three modes for your choice: Lossless mode (png, jpg, gif); Lossy mode (jpg); PNG 8 bit mode.
- Import the entire directory (including subdirectories) and output the images back without changing the original directory structure.
- Drag photos, folders onto the app to optimize them.
- Maintain the original dimension while shrinking pictures.
- Individual or batch processing.
- Upload optimized images to the web more faster.

Compatibility: OS X 10.6.4 or later

More info - http://www.effectmatrix.com/mac-appstore/Lossless-Photo-Squeezer.htm