Gem, Gender, Generic, Genius, Genre, Gentile, Gentle, Geriatric, George, Gerald, Germs, Gerry, Gerund, Giants, Gin, Gingersnaps, Ginormous, Giraffe, Gym, Gypsy, and Gyrate all start with a G but are pronounced like they start with a J.
SCUBA stands for “Self-Contained Underwater Breathing Apparatus”. You do not pronounce the U in SCUBA the same as the U in Underwater.
LASER stands for “Light Amplification By Stimulated Emission of Radiation”. You don’t pronounce the A in LASER like you pronounce the A in Amplification, nor the S as you do in Stimulated, nor do you pronounce the E the same as in Emission. (TASER, acronym for
“Thomas A. Swift’s electric rifle”, similarly pronounces S as a ‘z’ sound, rather than the ’s’ sound from Swift)
NATO stands for “North Atlantic Treaty Organization”, but you don’t pronounce the A in NATO like you do the A in Atlantic.
JPEG stands for “Joint Photographic Experts Group”. You don’t pronounce the P in JPEG the way you pronounce it in Photographic.
PIN stands for “Personal Identification Number”. You don’t pronounce the I in PIN the same as you do in Identification.
None of those except PIN were words prior to the acronym, and thus did not have widely accepted pronunciations.
PNG stands for portable network graphics. It’s official pronunciation? Ping.
The creator of the gif file format says it’s “jif” and that’s how it should be pronounced. End of story.