XnConvert
Pierre-Emmanuel Gougelet
XnConvert is a cross-platform batch image-converter and resizer with a powerful and ease of use experience. All common image formats are supported (i.e. JPG,PNG,TIFF) as well as supporting over 400 other image formats. Also available within the batch operations include rotating, adding of watermarks, adding of text along with many image-adjustment features such as brightness, shadows and more. XnConvert is free software for Windows, Mac, and Linux. Both 32-bit and 64-bit editions are available.