Thanks to user Nicola Galluzzi's comment, BIRME support webp format now. I heard about this wonderful image format before but I didn't follow up on its availability until I saw Nicola's commet recently. Why webp is wonderful? webp is a a newl image format developed by Google. It can produce smaller file size than JPEG with even better aulity. At the same time, it can support transparent background (alpha channel) like PNG format in a much smaller file size. That's not all, it can even store animations like GIF. It takes all the good things from 3 most commonly used formats.
Habits are the biggest enemy to innovation. We stop trying to improve when we get used to it, get comfortable to it.