This question has come up often enough to warrant putting it here:
The concept of "resolution" really only applies to a printout, not the
image itself, since the "resolution" is always fixed by the monitor.
Consequently, these images are not rendered at any one "resolution":
An image that is 1280 pixels wide, for example, is 17.7 inches wide if
you think of it as 72ppi (72 pixels per inch) or it's 10 inches wide
if you take it to be 128ppi or 4.25 inches wide if you think of it as
300 ppi -- "resolution" only enters the picture if/when you want to
print them, i.e. impose a size. Before that, they are simply "1280 by
1024 pixels" without any fixed notion of the size of a pixel (or the
number of pixels per inch).
Some image processing software (including PSP and PS if I'm not
mistaken) simply always set the "resolution" to 72 when there is none
hardcoded in the image.
Now if you'd like to make largerish prints at a high resolution, then
you may want to have renders with more pixels. If you'd like to print
something in 4x6 inches at 300ppi then you'd need a 1200x1800 pixel
image. But the same image could then be rendered at 6x9 inches at
200ppi. The images here are 1280x1024 (the older stuff) through
1920x1200 (the most recent things) and would thus print at 5x4 to
7.5x4.7 inches if printed at 256ppi.
On the other hand "dpi", i.e. dots per inch, is really a printer quality
statement and says how many droplets of ink the printer can put down
in a given area. But since a printer usually only has three or four
base colors, it will need several drops to mix some intermediate hue. If
you have a 600dpi printer and you print at 300ppi then each pixel is
approximated by four droplets of ink, which makes for a somewhat
coarse representation of subtle shades.
(This question came up sp often, in fact,
that I expanded on it here...
This page was written in early 2001 in fairly vanilla XHTML1.0 which
ought to be both XML and HTML-4 parsable. It contains a single small
chunk of CSS, mostly for the liquid layout (change the width of your
browser window to see that at work) and the occasional closable little
boxes on the left side here.
all of these open all the time. I tested this page back then in IE-6,
Konqueror-3.1, Mozilla-1. It works just fine in Lynx 2.8 under Linux
and Sun/Solaris (albeit without the thumbnail images) and Netscape6
under Solaris. And as of this writing (Jan 2017) it looks like it's
aged quite well.
The intent here is of course to create something that actually works
for everybody. Should you come across a browser (of this
century) that has problems with this page, please shoot me a line so
that I can have a look at it.
I do not like "HTML editors" and similar abominations
that produce monstrous files that are not in the least compliant with
the World Wide Web Consortium's standards and look horrible (or don't
work at all) with every browser except the exact version of the exact
browser the author was using.
It is not my intent to switch carreers at this point, but I'm
certainly available for small web-layout jobs if you like what you see