 | PPI and DPI and print |
| PPI and DPI and print |
PPI and DPI and print | ||
| oh my | ||
| Andy Leach (RedAndy) Post Count: Joined: | Msg: #1 Added: 2005-06-29 19:59:07 | |
| I think I'm trying to do the impossible, but well... If I have a 2240*1563 @ 144 resolution is there anyway I can tell, by doing some maths, what size it will print at if I increase the res to 300? If not then what data do I need to do this, and can I get it from EXIF? mtia, Andy [Edited: 21:29 - RedAndy ] | ||
| Bob Wallace (BobTrips) Post Count: Joined: | Msg: #2 Added: 2005-06-29 21:13:39 | |
| OK, here's my take. There's no hard and fast rule. The amount of important detail in an image will greatly determine how many pixels per inch (ppi) you need to do a 'good' job. Let's take an extreme example. You shoot a solid colored pink wall. One with no little flaws, but super smooth and evenly lighted. In this case you'd need only one pixel to make a print of any size, even huge. But as more detail enters the picture you need more "marker pixels" to indicate where those details begin and where something else stops. I've played around with ppi rates with my "Flower Vendor" and printed it out at ppi rates from 100 to 300. To my eye the quality reaches an acceptable level at around 180 ppi. 100 ppi really isn't bad and would probably be acceptable to the casual viewer - a good 'Granny' picture. From 'normal viewing distance' most people would most likely find the 100 ppi picture "just fine". To tell the difference between it and higher rez pictures I think you actually have to put them side by side and look carefully. So you've got 2240 x 1563 pixels. I'd say that you could make a quite good 12.4" x 8.7" print at 180 ppi with what you have. If you wanted to enter it in a very competitive contest or hang it in a very discriminating gallery you might want to get closer to 250 ppi. That would mean about a 8.9" x 6.25" print. (It seems that there is some research that most people can't discriminate improvements above 250 ppi but I haven't laid my hands on it yet.) How about running a test? I've uploaded the Fab Five (John, Paul, George, Ringo, and Elvis) to the site. Perhaps Ali can insert the links to the files. Download them and get them printed at 4" x 6". Look carefully at them and tell me what you think the correct order is from lowest to highest resolution. Later I'll tell you what the correct is. (Uprezzing your file to the 'best fit' for the particular printer is another issue.) | ||
| Andy Leach (RedAndy) Post Count: Joined: | Msg: #3 Added: 2005-06-29 21:28:18 | |
| Thanks Bob, close: not quite what I need to know but it sounds as though you know how to get me there. What I have is 1159 image files to put online for sale - I want to put next to the image what size they will be at 300ppi. The prevailing view, rightly or wrongly, is that 300ppi is the acceptable resolution for a quality print so that's what I want to put up. So in my example of an image at 2240*1563 @ 144 I'm guessing I'd get to around, erm, 7x5...? Also - how did you get to the 12.4" x 8.7" size for 180ppi and 8.9" x 6.25" for 250ppi? Experience or math? If it's math can you tell me how and if it's experience can I plug you into my PC for a bit :-) [Edited: 21:29 - RedAndy ] | ||
| Bob Wallace (BobTrips) Post Count: Joined: | Msg: #4 Added: 2005-06-29 21:48:42 | |
| Sure, drop the "@144" part. Then just divide by the ppi that you want. You've got the right answer. 2240/300 = 7.46" (Pixels divided by pixels per inch = inches.) And 1563/300 = 5.21" When you write "2240 x 1563 @ 144" you're inferring a 15.6" x 10.8" print. There's an old persistent myth that quality prints need to be made at 300 ppi. But with some printers you will actually get a better print at a lower ppi rate. It has to do with the native resolution of the printer (or something else that I don't understand). I'll bet that you could take your 2240 x 1563 and upsize it to a ~3000 x 2400 file (some cropping will be needed) and sell it for 8" x 10" prints with no problem. | ||
| Andy Leach (RedAndy) Post Count: Joined: | Msg: #5 Added: 2005-06-29 22:03:09 | |
Well that was far simpler than what was in my head, I really wonder about myself sometimes, and the 144 res I read in the data is irrelevant to my question. Good (: with some printers you will actually get a better print at a lower ppi rate -BobTripshmm, is that so, I really have to read up on this some more.Thanks for your help Bob, my life just got easier and I don't need to store the 300ppi anywhere :-) I'll bet that you could take your 2240 x 1563 and upsize it to a ~3000 x 2400 file (some cropping will be needed) and sell it for 8" x 10" prints with no problem -BobTrips We've printed a few here on 8x10 on a Canon i470d using cheap paper and they came out extremely well. They're on the wall right now, I imagine with a better printer and half decent paper they'd look excellent. | ||
| Bob Wallace (BobTrips) Post Count: Joined: | Msg: #6 Added: 2005-06-29 22:06:17 | |
| Have you got access to a good discount printing place? We've got drug stores with Kodak systems and Costco (big box discounters) with Fuji gear and can get a 8" x 10" or 8" x 12" print for $1.99 US. Or a 12" x 16" for $2.99. | ||
| Andy Leach (RedAndy) Post Count: Joined: | Msg: #7 Added: 2005-06-29 22:13:32 | |
| I think the cheapest I've seen has been about NZ$12 for an 8x10. Which is not huge, but when you're job hunting it's still a cost to avoid... Maybe I'll get some shipped from the states - do they accept emailed images? BTW - are you still having issues with my email address? The hosting company has closed the log saying that they'll monitor it, I'd like to give them a kick if it's still happening, cheers. | ||
| Bob Wallace (BobTrips) Post Count: Joined: | Msg: #8 Added: 2005-06-30 00:53:05 | |
| Hi Andy, Just fired a test email off to your #1 address. Haven't sent you anything recently so don't know if I'm having troubles or not. --- Prints. Have you checked for NZ online printers? There are multiple US printers that accept email orders. If you want I'll get you some names. And I can get you one in England. I posted some files for Adrian to look out. Emailed the files from here and he ordered prints on line - got them by snail mail a couple days later. That worked great. 4" x 6" for 9 pence. Whatever a pence is.... | ||
| Ali Watters (Ali) Post Count: Joined: | Msg: #9 Added: 2005-06-30 05:38:37 | |
| Would a little utility on Jeber help with this? I know it's a question that gets asked a bunch on the TT also. The idea - enter in width & height in pixels - and it says that for 300ppi you could get a 8"x10", 7"x4" but that 240ppi would give a 10"x12" (or whatever) - also notes if cropping would be needed - and suggests that if you don't want to crop increase canvas size to X by Y. Would also be a place for the fab five to be linked. Or choose a size from the drop down and it says what size canvas is needed at 300ppi and 240ppi. Quite a simple one to build... > That worked great. 4" x 6" for 9 pence. Whatever a pence is... About 2c at the mo ;) That's a good price - in Hungary I'm looking at about 2x that (maybe they do European delivery?) For my graphic design clients I used Photo Box. On the topic of extreme prints - I've had a photo from a digital rebel (6.3mp camera) (not taken by me) - blown up to a 4 feet by 3 feet canvas that's 48"x36" - and it looked great standing back a few feet, was used at a trade fair to grab attention. That cost £90 though! | ||
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