[OS X TeX] pdftex and bitmap images

Peter Dyballa Peter_Dyballa at Web.DE
Thu Dec 25 16:46:05 CET 2008

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.)



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

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