XnConvert

XnConvert is a highly recommended image conversion tool to change your picture from one format to another without any complications and in just a few simple steps.

The program is compatible with more than 500 different formats, including, of course, the typical ones like JPG, PNG, TIFF, GIF, BMP, and RAW. But you can also use much more specific formats that are only supported by applications as comprehensive as this one.

Before converting the image, you can specify some of the specific options that let you add a frame, signature, watermark, special effects, etc. You can apply all of these to a single picture or to a large batch of photos. You also have the possibility of saving the metadata for each file or even adding a background color if you want to change all the images to the same size without changing their proportions.

Ultimately, XnConvert lets you convert batches of images in a totally customizable way. You can even add the same filter to all of the files.