Wikipedia:Tip of the day/January 7
For images, there are free tools like GIMP and ImageMagick, and commercial ones like Photoshop that provide a variety of processing filters. The preferred formats are Scalable Vector Graphics (SVG) for drawings, and PNG for pictures. You may also use JPEG. Vector graphics are preferred to raster images for drawings, because they can be scaled as needed without losing information, and because they can be more easily edited. Please remember to follow our guidelines and policies when uploading images.