[OS X TeX] pdftex and bitmap images

[Peter Dyballa]

Am 25.12.2008 um 14:32 schrieb André Bellaïche:

>>> Does anybody knows how pdftex + graphicx processes bitmap images  
>>> when a reduction factor is applied by \includegraphics
>
> Yes, of course: scaling. Is it not the same as reduction by some  
> factor?


Well, a soup is easier reduced to a sauce than scaled ...

In pdfTeX the image is put as is into the PDF. The viewer or printer  
or renderer are informed of a viewport and a scaling operation. So  
they try to make the picture fit into its frame. And of course they  
adapt (by changing, reducing) the resolution of the picture – a 1.200  
DPI picture can't easily be displayed on a 72 DPI screen or printed  
by a 300 DPI laser printer.

When a 300 DPI picture is set by a 1.200 DPI typesetter the  
resolution is not changed. (And I also presume that a 30 DPI picture  
does not get "enhanced" to be displayed on a 72 or 96 DPI screen.  
It's as with TV on some digital screen, something gets distorted.)

--
Greetings

   Pete

We are usually convinced more easily by reasons we have found  
ourselves than by those which have occurred to others.
				– Blaise Pascal