Upgrade your account to a Community Supporter account and remove most of the site ads.

Reply to thread

Message: <blockquote data-quote="Fast Learner" data-source="post: 471602" data-attributes="member: 649">dpi and lpi examplesPrint on demand (and all digital printing) is hampered by resolution issues, though it's beginning to look like newer PoD equipment can print reasonably well (better than most home printers, anyway).Here's a little more lpi vs. dpi info that may help.DPI stands for Dots Per Inch (obviously, perhaps), and refers to the smallest-sized dots -- actual little digital (on/off) dots -- the printer can cram into a 1-inch space. Things tend to look better than photocopy quality at about 600 dpi, and tend to look "perfect" to the average (but not super-picky) human eye at 1200dpi. All solid-color (black, cyan, magenta, or yellow) line art and text can take full advantage of the dpi of the printer.LPI stands for Lines Per Inch, and refers to the number of lines of variable-sized dots that fit along a 1-inch stretch when creating a "screen" or "halftone". Printers simulate shades of gray (or shades of cyan, magenta, and yellow) by clumping dpi dots together into bunches, effectively creating variable-sized dots. Anything that's not pure black, cyan, magenta, or yellow is simulated by creating arrays of these variable-sized dots. That means all photos, anything that's photo-like (JPEGs, TIFFs, BMPs, etc.), and any colors other than the four i listed (red is composed of little dot-clumps of magenta combined with little dot-clumps of yellow, for example).Most digital printing shoots for 256 shades of gray (or cyan, magenta, or yellow) in a given halftone to give it the most realistic look possible, but to make 256 different-sized dots (clumps of dots), if the resolution (dpi) isn't high enough the clumps of dots get really big. As such there's a constant tradeoff between shades of color and clumped-dot size.Here's how they compare (numbers from memory but are close):300 dpi printer is capable of 37 shades at 53 lpi. 53 lpi is extremely coarse: you can't make out any details at all. As such most 300dpi printers by default only print about 25 shades of gray at about 65lpi, which still looks lousy. Virtually nothing commercial (except for pizza flyers, perhaps) is printed at this resolution/screen combination.600 dpi printer is capable of 50 shades of gray at 85 lpi. 85 lpi is the resolution of poor-quality newspaper photos.1200 dpi printer is capable of around 150 shades of gray at 133 lpi. This is what "decent-quality" printing looks like. Many magazines are printed at this resolution and screen. If a PoD device printed at this quality you'd have something tht looked not quite as good at the stuff you mostly see on store shelves, but it's quite reasonable.2400 dpi printer (imagesetter, usually) is capable of 256 shades of gray at 250 or so lpi. This is very good quality, as nice as you'll see in almost any professionally printed material.To get a sense of it...Newspapers: 85-100 lpiMagazines that aren't focused on photography: 133-150 lpiMagazines where photography is important but not essential: 200 lpiMagazines where the whole point is photography, like Playboy: 300 lpiSUMMARY: If you're getting your PDF printed on demand and you want it to look as good or at least nearly as good as the good stuff on store shelves you'll need at least a 1200dpi printer than can create 133 lpi halftones/screens.</blockquote>

Verification