Printing Question - Rephrased

Thomas McGrath III 3mcgrath at adelphia.net
Fri Mar 11 09:29:58 EST 2005


Converting dimensions in Pixels to Inches

Images are described by their dimensions in pixels. However, printouts 
are described in inches or centimeters. If you have a digital image and 
want to make a printout then to know how large an image will be when 
displayed or printed, you convert from pixels to inches (or cm). To do 
so, you divide the image's dimension in pixels by the resolution of the 
device in pixels per inch (ppi). For example, to calculate the 
dimensions of a 1500 x 1200 image being printed at 300 ppi you divide 
as follows:

Width: 1500 pixels ÷ 300 ppi = 5"
Height: 1200 pixels ÷ 300 ppi = 4"

The result is a 5" x 4" print. However, if the output device prints 600 
ppi, the result changes to a 2.5" x 2" print as follows:

Width: 1500 pixels ÷ 600 ppi = 2.5"
Height: 1200 pixels ÷ 600 ppi = 2"

For more info go here: 
http://graphicdesign.about.com/library/weekly/aa070998.htm?once=true&

Or do a quick search for DPI PPI conversions on the web

A start,

Tom

On Mar 11, 2005, at 9:03 AM, Len Morgan wrote:

>
> I know that there are 72 points to an inch when I print but I don't 
> know how to scale this to dpi on a printer or dpi on the screen for 
> that matter.  I'm trying to print ID Badges with a photo on them and 
> I've used the example from the video but it seems that trial and error 
> is the only way I'm going to get things to fit properly.  What I'd 
> like to know is how to map pixels (which RR uses) to physical 
> distances on the paper so I can, for example, put the photo in the 
> upper right hand corner of a 2.125 x 3.375 inch plastic card.
>
> If I do the trial and error once (when my printer is set at 600 dpi, 
> aren't the dimensions going to be 2 times (4 times?) bigger if I use a 
> 300 dpi printer?  Can I get to the printer attributes to determine the 
> dpi the printer is going to use and then calculate some constants for 
> scaling my card to fit?

Thomas J. McGrath III
SCS
1000 Killarney Dr.
Pittsburgh, PA 15234
412-885-8541


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