Convert images from one format to another using Preview.
PREVIEW’S IMAGE– EDITING AND annotation tools do more than you might realize. In addition to cropping, adjusting the size of images and converting them to a different format, you can also adjust levels, sharpness and color temperature. There are vector drawing tools, as well as a shape selector so you can add shapes to an image or PDF. That makes it easy to, for example, draw a box around a section of a PDF to highlight before sharing.