XnConvert

Company: XnView
Web: http://www.xnconvert.com/

XnConvert is an easy image converter for graphic files, photos and images available on Windows, MacOSX and Linux. It supports more than 400 file formats (jpeg, tiff, png, gif, camera raw, jpeg2000, WebP, OpenEXR, ...). You can resize, add a watermark, change contrast, brightness or gamma, apply filters and many other things.