Convert png64 to jxl

What is the difference between .png64 and .jxl?

Description: A PNG file is an image file stored in the Portable Network Graphic (PNG) format. It contains a bitmap of indexed colors and uses lossless compression, similar to a .GIF file but without copyright limitations. PNG files are commonly used to store graphics for web images.; A JPEG XL file is an image saved in a compressed graphic format currently under development by the Joint Photographic Experts Group (JPEG). It supports wide color gamut and HDR (High Dynamic Range), alpha channels and animation frames while providing visually lossless compression. Images can be converted back and forth between JPEG XL and JPEG without loss of quality. Converting a regular JPEG to JPEG XL reduces the file size by 22%. JPEG XL files can be used to store any type of image content.