OrbConvert converts your image files online. Amongst many others, we support PNG, JPG, JPEG, WEBP, GIF, SVG and TIFF. You can use the options to control image resolution, quality and file size.
From
Portable PixMap
One of the Netpbm family: the simplest possible way to store a full-colour image, with no compression at all. Files are large, and it carries no transparency.
All PPM conversionsTo
Flexible Image Transport System
The standard format of astronomy, carrying scientific data alongside the image. Files are typically far larger than the same picture as PNG.
All FITS conversions