posted
I am trying to find a reference scale that indicates the correct dpi on digital signs for the best viewing at different distances. For instance really large billboards are printed at 27 dpi or lower. At an image viewing distance of five feet or less 600 dpi is required. Too much dpi at a long distance makes the images go blurry, and a lower dpi will make it more crisp. There is a Mac tool truck in town that has a chrome tool image on the side that really pops at 200 feet and it's at about 20 dpi. All the articles I can find denigrate into discussions on saving money on ink at a lower dpi; unfortunately that’s not my concern, my concern is with the best dpi at varying distances for maximum pop. I hope someone can point me in the right direction.
-------------------- Brian Crothers CR Signs 1790 C Tamarac St. Campbell River B.C. V9W 3M6 briancrothers@crsigns.ca Posts: 82 | From: Campbell River B.C. Canada | Registered: Apr 2002
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posted
I find that as far as digital printing goes for signage, a 300 dpi print works just fine at 2 ft. plus distance. If you're getting into photographic or giclee output, 720 and higher is a must. On big prints from a scan, remember that when you scan at a given dpi setting, your output's dpi is cut in half when you double the size of the scan....ie. scanning a 5X7 print at 600dpi will give you 300dpi output at 10X14.....and the quality of the item you are scanning has everything to do with the quality of output. You cant make a silk purse out of a sow's ear! I didn't answer your question, but I hope this helps a bit.
posted
The definition of normal visual acuity is the ability to resolve a spatial pattern separated by a visual angle of 1/60th of a degree. (Just looked it up)
If it were that simple, then we could have a rule of thumb like the 1" per 10 feet of letter height.
So, if 300 dpi is good at 3 feet, then 150 would be good at 6, 75 at 12, and so on. It would seem that at some point, the white space would overpower the dots, and the image would be lost. It doesn't appear to be that simple. Maybe it has to do with the way our eyes perceive shapes. Vic G
-------------------- Victor Georgiou Danville, CA , USA Posts: 1746 | From: Danville, CA , USA | Registered: Dec 1998
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posted
thanks very much for the input and bump. I'm not asking about the scanning resolution, or the file saved dpi, or the size of the file. THE QUESTION IS: at what DPI do you PRINT at for what distance? There is a BIG difference in quality of view or POP, if the dpi is too HIGH at a large distance. For instance a detailed photo at 300 dpi at 30 feet is viewable. At 120 feet it's too blurry and should have been printed at a LOWER dpi... (the printing press guys will agree; the ones here don't do large format so they don't have a scale) so this is a SIGN QUESTION not a printing press question...
-------------------- Brian Crothers CR Signs 1790 C Tamarac St. Campbell River B.C. V9W 3M6 briancrothers@crsigns.ca Posts: 82 | From: Campbell River B.C. Canada | Registered: Apr 2002
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