ABIC is a multiplatform tool for converting images from and to a wide variety of formats, for example: JPEG, TIFF, PNG, JPEG-2000, WebP. It can also read some historic ones, in particular Amiga IFF (ILBM).
ABIC is completely free, open sourced, and is also entirely nag-free.
- Supports dozens of image file formats
- Runs on Windows, Mac OS X and many more OSes
- Multithreaded (can use all cores of a CPU)
- Portable software (also runs without installation)
- Can process images with 16 bits depth (only for certain formats, like TIFF and JP2)
Works as advertised, just converted 400 oddly formatted TIFF files into PNG.