How come when I measure then screen, an inch is not an inch?

In article <1151119625.563717.155530.DeleteThis@i40g2000cwc.googlegroups.com>,
"Ron" <roninabox.DeleteThis@gmail.com> wrote:

> I'm sitting here trying to develope an eps-friendly application and I'm
> having trouble with the resolution. Why does Illustrator and Photoshop
> at 100% show inches that are not real inches on my screen? I'm
> programming in Java, and it tells me that an inch is an inch; that is,
> in my graphics program, the ruler is true on the screen. What's going
> on here?
>
> Ron

Screen resolution, most likely. Most Adobe graphics programs use the
"traditional" 72 DPI = 72 points/6 pica = 72 pixels per inch on screen
(the DTP points, that is) for WYSIWYG display. If you're using some
other display resolution, the system obligingly scales the application's
output to fit that one point per pixel scheme as best it can.

I imagine what you're seeing is the Java framework being aware of
display dimensions and resolution idiosyncrasies and taking them into
account when display time comes around. It is supposedly more a system
API rather than an application, so has a much more cozy relationship
with the OS.

Of course, I could be wrong.



- Doug
 >> Stay informed about: How come when I measure then screen, an inch is not an inch? 

In article <justdoug-D279B8.21120423062006.DeleteThis@news-server.socal.rr.com>,
Doug Winger <justdoug.DeleteThis@socal.rr.com> wrote:

> In article <1151119625.563717.155530.DeleteThis@i40g2000cwc.googlegroups.com>,
> "Ron" <roninabox.DeleteThis@gmail.com> wrote:
>
> > I'm sitting here trying to develope an eps-friendly application and I'm
> > having trouble with the resolution. Why does Illustrator and Photoshop
> > at 100% show inches that are not real inches on my screen? I'm
> > programming in Java, and it tells me that an inch is an inch; that is,
> > in my graphics program, the ruler is true on the screen. What's going
> > on here?
> >
> > Ron
>
> Screen resolution, most likely. Most Adobe graphics programs use the
> "traditional" 72 DPI = 72 points/6 pica = 72 pixels per inch on screen
> (the DTP points, that is) for WYSIWYG display. If you're using some
> other display resolution, the system obligingly scales the application's
> output to fit that one point per pixel scheme as best it can.
>
> I imagine what you're seeing is the Java framework being aware of
> display dimensions and resolution idiosyncrasies and taking them into
> account when display time comes around. It is supposedly more a system
> API rather than an application, so has a much more cozy relationship
> with the OS.
>
> Of course, I could be wrong.

Doug, with all due respect, *when* have you been wrong? I think we all
know you are the Illy guru here. : )
>
>
>
> - Doug

--
C Pierce
 >> Stay informed about: How come when I measure then screen, an inch is not an inch? 

In article <1151123666.542152.116970.RemoveThis@i40g2000cwc.googlegroups.com>,
"Ron" <roninabox.RemoveThis@gmail.com> wrote:

> I don't know. It seems to me that Java is telling me the true inch.
>
> Doug Winger wrote:
> > In article <1151119625.563717.155530.RemoveThis@i40g2000cwc.googlegroups.com>,

> > Screen resolution, most likely. Most Adobe graphics programs use the
> > "traditional" 72 DPI = 72 points/6 pica = 72 pixels per inch on screen
> > (the DTP points, that is) for WYSIWYG display. If you're using some
> > other display resolution, the system obligingly scales the application's
> > output to fit that one point per pixel scheme as best it can.
> >
> > I imagine what you're seeing is the Java framework being aware of
> > display dimensions and resolution idiosyncrasies and taking them into
> > account when display time comes around. It is supposedly more a system
> > API rather than an application, so has a much more cozy relationship
> > with the OS.
> >
> > Of course, I could be wrong.

So are Photoshop and Illustrator, and possibly with greater actual
object fidelity when output time rolls around. They're just not
+displaying+ it to fit a ruler's measure on your screen, as they expect
a display resolution of 72 pixels per inch. There's a reason WYSIWYG
resolution on a 21" monitor is 1152 x 870; it displays (within reason)
one inch as one inch when those applications are up to bat and showing
off at 100% magnification. Each pixel represents each point of measure,
with 72 to the inch being the DTP standard. The ruler measures properly
then, and you get one inch of the application ruler measuring one inch
on the display's territory (again, within reason).

Change that display resolution however and, while that application's
points-to-pixel relationship stays the same, the pixels per inch showing
changes. Higher resolution gets a smaller ruler showing, with lower
magnifying it.

Java, being intimate with the OS, probably knows enough to ask the
system "how many pixels does the current display require to display one
inch of measure on one inch of display?" Applications have to live with
what they're handed and know how to do.


- Doug Again
 >> Stay informed about: How come when I measure then screen, an inch is not an inch? 

Ron wrote:
> I'm sitting here trying to develope an eps-friendly application and I'm
> having trouble with the resolution. Why does Illustrator and Photoshop
> at 100% show inches that are not real inches on my screen? I'm
> programming in Java, and it tells me that an inch is an inch; that is,
> in my graphics program, the ruler is true on the screen. What's going
> on here?
>
> Ron

fyi, i asked this same question in a recent digital photography class i
took and got told that i was slightly retarted! lol!
 >> Stay informed about: How come when I measure then screen, an inch is not an inch? 

On 23 Jun 2006 20:27:05 -0700, "Ron" <roninabox.TakeThisOut@gmail.com> wrote:

>I'm sitting here trying to develope an eps-friendly application and I'm
>having trouble with the resolution. Why does Illustrator and Photoshop
>at 100% show inches that are not real inches on my screen? I'm
>programming in Java, and it tells me that an inch is an inch; that is,
>in my graphics program, the ruler is true on the screen. What's going
>on here?
>
>Ron

I don't claim to really know. There are too many variables possible
for a "one size fits all" answer (resolution, DPI).

I normally use a resolution of 1280X1024 on my Dell 19" (crt), Windows
XP system using the default 96 DPI.

When I change the resolution to 1024X768 I get an almost perfect 1 to
1 relationship. That is, in the Illustrator window, on the ruler at
the top of the window, one inch displayed actually measures one inch
with a ruler in my hand.

When in 1280X1024 res, one inch on my ruler in Illy is about 13/16
inch on the ruler in my hand.

Of course, if I change my DPI from 96 to something else, both of the
above change.

None of the above really matter to me anyway. If I want to see what a
particular image/object/drawing would look like at full scale, actual
size I change the scale of the Illy document.

At 1280X1024 on my machine, a 72 pt line will physically be one inch
long as measured with a ruler when the Illustrator window is scaled to
120%.

jbl
 >> Stay informed about: How come when I measure then screen, an inch is not an inch? 

In article
<1151643116.528046.215030.TakeThisOut@b68g2000cwa.googlegroups.com>,
"None" <clark_kent_712000.TakeThisOut@yahoo.com> wrote:

> Ron wrote:
> > I'm sitting here trying to develope an eps-friendly application and I'm
> > having trouble with the resolution. Why does Illustrator and Photoshop
> > at 100% show inches that are not real inches on my screen? I'm
> > programming in Java, and it tells me that an inch is an inch; that is,
> > in my graphics program, the ruler is true on the screen. What's going
> > on here?
> >
> > Ron
>
> fyi, i asked this same question in a recent digital photography class i
> took and got told that i was slightly retarted! lol!

I was wondering a similar thing: in my Illustrator 8 on a Mac, on
a screen of 1600 by 1200 for a 20" giving 100px per inch, I don't
get anything close to an accurate reading at 100% viewing of my
art work as set up in document set-up. Does this mean that the
program is not understanding my Dell 20" LCD monitor?

--
dorayme
 >> Stay informed about: How come when I measure then screen, an inch is not an inch?