The image files with an EXR extension are the open-source high-dynamic image files created by Industrial Light & Magic visual effects company. These raster image files store images in OpenEXR format ...
You can convert a JFIF file to JPG, though the two formats are nearly identical, and most software will open a JFIF file as a JPG.
If you have an iPhone running iOS 11 (or later) or a Mac running macOS High Sierra (or later), chances are that, at some point in time, you might have come across the HEIF (or HEIC) and HEVC formats ...