I think the article could have used a little more on chroma subsampling ("downsampling," per the article). A couple examples: It is basically an optional step (in the case of 4:4:4). And the visual impact on heavily saturated colors (looking at you, bright red).
Really good introduction, well written.
Talks about a technology. Misspells its name.
Ctrl-F gives me 17 results for JPG, 3 results for JPEG.
As far as I'm concerned, they're interchangeable. I can't be the only one who thinks so.
JPEG is an acronym for “Joint Photographics Experts Group”. So I guess “JPEG” refers to a collection of humans. They specified an image format also called JPEG, which has been implemented as the JPEG file format, whose filename suffix is “.jpg”
What I'm saying is that at no point was I confused about what they were trying to communicate, so as far as I'm concerned it makes no difference outside of just being pedantic.