Re: [Usability] "Finish" vs. "Close" in gnome-control-center dialogs

[Liam R E Quin <liam holoweb net>]

On Mon, 2006-03-27 at 18:08 +0100, Calum Benson wrote:

> > Just so I've got this right -- you want FEWER or NO
> > full size screenshots in the docs?
> 
> That's certainly the approach the Sun guys tried to take when they  
> wrote GNOME docs.
> 
> (Isn't it still common practice in the publishing industry to reduce  
> all screenshots to 60-70% anyway, just because they look too big on  
> the page at full size?  I almost never use full-sized screenshots if  
> I'm working on UI specs, mockups etc.)

This reply is very off-topic but might be useful....

What does "size" mean for a printed screenshot?  For a 19 inch
screen you'd need awfully big paper to do them at 100%.

Since most typesetting and printing equipment works at at least 1200
dpi, but usually for manuals in black and white, with dot screens
to simulate grays, you can calculate the effective pixels per inch
for, say, 64 distinct levels of grey: you'd need an 8x8 grid (at least),
so that would give you 150 lines per inch (1200/8 = 150).  A screenshot
that's 1600 pixels wide would hence come out at (1600/150) or 10.67
inches wide.  At 2400dpi you could go to 5.33 inches wide without loss
of detail.

However, 150 lines per inch is almost as expensive as stochastic
screening, and most offset litho printers would want something
lower, so they don't have to stop the presses and clean the plates
as often.

If you went with 25 levels of grey instead of 64, you'd have a 5x5
grid, a common size for PostScript printers.  A 2400dpi typesetter
would then give you an effective resolution of 480dpi, so your
1600x1200 screenshot would come out as 3.33 x 2.5 inches on paper.

If your image was originally 96dpi, reducing it by two thirds would
take it to 144dpi, which turns out to work well with a 72lpi screen,
which is actually much more realistic.  In theory 72 lines per inch
gives over 1000 distinct grey levels on a 2400 dpi device, or, at
1200dpi, it gives 256 levels, which works out very usefully.  In either
case there's enough margin to make symmetric dots (little circles),
the default PostScript screening pattern, and still have a readable
image.

When people talk about reducing the size of a bitmap for printing,
though, most often they mean editing the Print Size tag, which
e.g. Adobe Photoshop uses to determine the printed size of an image.
This is a piece of metadata that is entirely independent of the
actual resolution of the image, something that confuses almost
every PhotoShop user at elast at first.

Liam

-- 
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Ankh: irc.sorcery.net irc.gnome.org www.advogato.org