Comment by blenderob
5 days ago
The article starts out with an assertion right in the title and does not do enough to justify it. The title is just wrong. Saying pixels are like metres is like saying metres are like apples.
When you multiply 3 meter by 4 meter, you do not get 12 meters. You get 12 meter squared. Because "meter" is not a discrete object. It's a measurement.
When you have points A, B, C. And you create 3 new "copies" of those points (by geometric manipulation like translating or rotating vectors to those points), you now have 12 points: A, B, C, A1, B1, C1, A2, B2, C2, A3, B3, C3. You don't get "12 points squared". (What would that even mean?) Because points are discrete objects.
When you have 3 apples in a row and you add 3 more such rows, you get 4 rows of 3 apples each. You now have 12 apples. You don't have "12 apples squared". Because apples are discrete objects.
When you have 3 pixels in a row and you add 3 more such rows of pixels, you get 4 rows of 3 pixels each. You now have 12 pixels. You don't get "12 pixels squared". Because pixels are discrete objects.
Pixels are like points and apples. Pixels are not like metres.
> When you multiply 3 meter by 4 meter, you do not get 12 meters. You get 12 meter squared.
"12 meter(s) squared" sounds like a square that is 12 meters on each side. On the other hand, "12 square meters" avoids this weirdness by sounding like 12 squares that are one meter on each side, which the area you're actually describing.
that's just a quirk of the language.
If you use formal notation, 12 m^2 is very clear. But i have yet to see anyone write 12px^2
It's one that really bothers me because of the unnecessary confusion it adds.
As for the rest, see GGP's argument. px^2 doesn't make logical sense. When people are use pixels as length, it's in the same way as "I live 2 houses over" - taking a 2D or 3D object and using one of its dimensions as length/distance.