From Francesco Mondello:
Converseen is an open source project written in C++ with the powerful Qt4 libraries. It supports more than 100 image formats. You can convert and resize an unlimited number of images to any of the most popular formats: DPX, EXR, GIF, JPEG, JPEG-2000, PDF, PhotoCD, PNG, Postscript, SVG, and TIFF. With Converseen you can save your time because it allows you to process more than one image with one mouse click. With converseen you can carry out a single or a multiple conversion, resize one or multiple images, and compress images for your web pages.