On Tue, 2017-02-07 at 01:26 -0700, brynn wrote:
Hi Luca, I'm starting to understand better now. Thank you for taking the time and effort to explain. From your previous message, now I'm down to this place, where I'm stuck: "Here is the point: ...... Example: an A4 is 210 mm x 297 mm. Let's convert it in px using the 90 DPI convention: 210/25,4*90 = 744 px 297/25,4*90 = 1052 px " I think it uses math symbols that I don't understand. (I've learned math with that ancient world of inches, feet and yards, rather than metric system.)
Is it 210 divided by 25? If it is, why do you divide by 25?
I think 4* 90 means 4 times 90, but I don't understand where the 4 comes from. And the comma is foreign to me, if it means anything more than pause.
25,4 is a different way of writing 25.4 (common, for example, in Europe). So one has 210 ÷ 25.4 × 90 = 744 (approximately). Or with units (using 90 px per inch and 1 inch per 25.4 mm):
90 px 1 in 210 mm × ----- × ------- = 744 px 1 in 25.4 mm