Re: [Gimp-user] File size too large

[Liam R E Quin <liam holoweb net>]

A minor nit, but one that can cause quite a bit of confusion...


On Thu, 2017-04-27 at 13:35 -0400, Mark Morin wrote:
> . Most monitors display at 72 dpi.

This has not actually been true for many years. Macs used to display at
72dpi 15 to 20 years ago, for fidelity with PostScript laser printers
and typesetting equipment.

My laptop is actually closer to 144dpi. However, for the Web, CSS
assumes a baseline of 96dpi - that is, 1px in CSS is 1/96". Modern
Apple systems are closer to 300dpi and that's starting to be more
common in Windows systems too, so you can add a scale factor for images
to get higher pixel density; the ipad uses 3x these days I think.

To send to a printer, for an art magazine you want 300 pixels per inch,
so that they can halve it when they make a 150 line per inch screen;
for newsprint at a 75 line per inch screen you need to send 150 ppi.
The print world has changed a lot in the past decade because of digital
plates.


> If you
> have a 2" x 2" image at 72 dpi but convert and upload it to 144 dpi,
> it
> is going to display on screen as 4" x 4".

If you try this with a ruler and a Web browser you might be surprised
:) (depending on how your system is configured). It's changed.

The exact result you get will also depend on how you "convert" to
144dpi - whether you just change the dpi metadata in the image or
whether your image program inserts more pixels, but don't expect an
exact size on any monitor.

Best,

Liam

-- 
Liam R E Quin <liam holoweb net>