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Tip #85 - DPI vs LPI vs PPI...

[ I still don't understand this whole lpi/dpi thing... we're preparing ads for newsprint... HELP the graphics look awful!

DPI = Dots per inch = units used to measure the resolution of a printer
LPI = Lines per inch = The offset printing 'lines' or dots per inch in a halftone or line screen.
PPI = Pixels per inch = the number of pixels per inch in screen/scanner file terms.

Don't be confused by the terms. David Blatner introduced us to SPI in his 1993 "Real World Scanning" book (highly recommended) meaning "samples per inch".
__ In terms of output which is going to the newspaper, let me throw a wrench into the whole project here... since newspaper reproduction is so poor, and you're left at the variables of the press and paper, it sometimes matters not how good the original image is, or your hard image editing work. It still turns out lousy. If you've ever stood at the end of the web-press and watched the ink fountain ride up, then down, you'll know what I'm talking about.
__ Here's a new twist: how about NOT sending the paper a halftone, or any photo that needs screening and send straight line instead? (Some of you stepping back in shock.)
__ Take your image, convert it to grayscale, then making sure the resolution is at least 300 ppi, convert it to a "Dithered" bit map? Try this and see if the results are not very much like the famous Heliographs which always reproduce wonderfully in newsprint.
__ Now, if you must go halftone, here's the key
__ LPI x 2 = PPI.

In other words the minimum for faithful reproduction is 2-times the line screen in use. Many of the purists will say 2.2 times. Okay, go with 2.2.
__ So, if the newspaper is using an 80 line screen (many do) then you should have a minimum of 160 ppi resolution. Better yet... find or create a graphic in Illustrator and supply it to the paper as a true line shot. That way you're sure it will be a hit!

Design & Publishing Center . / . Photoshop . / . Tips & Tricks

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