This is a front-end for open source tools: OptiPNG, pngcrush, advpng, jpegtran and jpegoptim.
Images are made smaller (in terms of disk size) by recompressing them using best combination of compression settings, bettter algorithms, and by removing optional, invisible information like comments.
ImageOptim takes advantage of multi-core and 64-bit CPUs.
What is new in this release:
- Option to Stop optimizations earlier (keeping progress made so far)
- Removal of "Where from" OS X metadata
- Lighter/faster default config on slow machines
- Updated pngcrush
- Autolayout used for the main window
What is new in version 1.5.4:
- Added Revert to Original option (restores unoptimized file)
- Added cache of already-optimized files. In some cases ImageOptim will be able to quickly skip files it knows it can't optimize any further