> A point is 1/72 of an inch. Screen dpi's only purpose is to > translate a measurement in inches to pixels.
I also wanted to make one other point. It's been said directly and indirectly, but maybe this explanation (and analogy) may help. Consider looking at a road map. There is a scale on the map. It may say something similar to "10 mm = 5 km". On a computer it is a similar representation of scale. When you see 96 DPI, that means that there are 96 dots used to convey the visual representation of a 1-inch object at 100% magnification. It IS NOT SAYING that it will physically measure one inch on screen. It can become confusing for two reasons -- at least in my mind. If you come from a print background you are used to hearing 72 points = 1 inch. Then there were laser printers that were 300 dots per inch, then 600 dots per inch, and imagesetters/RIPs that worked in 1200 and 2400 dpi. In each of those cases, the measurement, that is 1 inch, was made up of the indicated number of dots. Enter computer monitors. In the wild west days of desktop publishing, the Mac OS ran at a default of 72 dpi. This caused many people to begin to associate monitor and OS resolutions to physical measurements, because it was the same "ratio" of 72 points to 1 inch. With the advent of 96 dpi as the default OS resolution setting on both Mac and Windows, people naturally were inclined to interpret that as meaning ONE INCH ON MY MONITOR = 96 PIXELS. No! Making matters worse, depending upon the physical size of your monitor AND the resolution it was running, you might find that 96 dpi was "nearly" one inch. (This is the case with 1920x1200 resolution on a 24" monitor. It is somewhere in the ballpark.) So with that, if you were a designer or someone involved in graphics, or simply someone that is very anal retentive, you get frustrated about the discrepancy when a 1" object at 100% measures 1.25 inches measured with a ruler against the screen. But that is because you've forgotten that a monitor's resolution is about SCALE, not the physical onscreen measure, similar to the scale on a map. It's easy to get tripped up by this, because unlike a map, the scale is not something obvious, such as 1 inch = 25 miles. It is more akin to seeing a map scale that says, 1 inch = 1.25 inches. When you are dealing with similar scales, as is the case with the later, it is easy to get twisted up. I also liken it to the difference between MARK-UP and PROFIT MARGIN. A 25% mark-up is not the same as a 25% profit margin. It's actually a 20% profit margin. But the values are similar enough that it's easy to get them convoluted, and both are accurate depending upon WHICH DIRECTION you view the relationship from. ...Rob ____________________________________ Rob Emenecker @ Hairy Dog Digital www.hairydogdigital.com Please note: Return e-mail messages are only accepted from discussion groups that this e-mail address subscribes to. All other messages are automatically deleted. ______________________________________________________________________ css-discuss [cs...@lists.css-discuss.org] http://www.css-discuss.org/mailman/listinfo/css-d List wiki/FAQ -- http://css-discuss.incutio.com/ List policies -- http://css-discuss.org/policies.html Supported by evolt.org -- http://www.evolt.org/help_support_evolt/
