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View Full Version : Photo resolution vs. printout size



meng-chieh
10-14-2004, 05:29 PM
Is there a chart listed somewhere that will tell me, roughly of course, the relative print out size with certain resolutions?

Example: for 1024 x 768, use 4 x 6 photo paper.

Thanks!

D70FAN
10-14-2004, 06:51 PM
Is there a chart listed somewhere that will tell me, roughly of course, the relative print out size with certain resolutions?

Example: for 1024 x 768, use 4 x 6 photo paper.

Thanks!

You will get all sorts of answers. The rule of thumb is: Print at as close to 300dpi as possible, and use 150dpi as a minimum.

Your example: 1024 x 768 divided by 300dpi = 3.41 x 2.56. Divided by 150dpi = 6.82 x 5.12. so for minimum quality a 5 x 7 print and for best quality a 3 x 4 print. So your 4 x 6 (in the middle) print will turn out fine.

Note: I have printed at 120dpi and the result was ok if viewed from a distance. For 4 x 6 120dpi might still be ok ;)

meng-chieh
10-14-2004, 09:10 PM
Thanks! Really appreciate it!

brianrehmann
10-29-2004, 05:45 AM
Thanks for the good info.

ZERO-D
11-23-2004, 04:35 AM
It always amazes me that NOBODY ever actually compares inkjet output from resolution to resolution and especially printer to printer. A site like this forum for inkjet printing is in need big time. If someone knows of one, please mention. Here's what seems to work for me: I have Canon S9000 13x19 printer w/lyson continuous inking rig with pigment inks, 2 Epsons 880 & C80, an HP all-in-one, and well I have 3 large format HP printers; HP DJ 500 42", 800 24", 5000 42" UV. With all these printers it is the rare file that will actually print more detail when it's over 150dpi. Especially for the large formats, it's just waisted time and effort to work that big. At 150 DPI with a truly high quality scan, photo capture w/excellent exposure and focus, etc you will see detail that borders on microscopic. You can't really see the individually printed dots. You may need to use some kind of quality/color print test image out there to believe me, but when a quality image with decent color management shoots to anybody's printer, it will be impressive! Conversely, you can also take a web sized gif of say a hawaiian palm tree on the beach and blow it up to window blind size and use some effects on it at high res and you will get something amazingly cool, if you have a decent eye and preview at 100% along with 25% or whatever works to see entire image on-screen+detail before committing. If you have Photoshop use color mgmt.! Here's my process, check out camera docs for ICC palette if any = sRGB IEC61966 2.1 for me (Nikon 990). Now in Photoshop open an image and set "view/proof set-up = sRGB IEC....." keep image numbers if it looks better but mostly go below and select "Blackpoint etc YES, and Dither YES. By the way, I guess you should go "color preferences/ and set RGB profile as sRGB....or cameras profile if you focus on this work only. Then spin triangle to advanced settings and I say "ask before opening" on files with other palettes, Blackpoint YES etc, same as above. Gamma 1.0 if it asks. THEN go to "image/mode either ASSIGN PROFILE and choose, or CONVERT TO PROFILE, whichever makes since in your case. OH desaturate monitor colors by 20% in colorprefs window is a good idea. BUT FIRST CALIBRATE your monitor (actually before all this is the best way) BUT you can fight up river like me. ONE STEP LEFT, what to send to printer? This varies a lot but I either preview the printer profile appiled in Photoshop in "image/mode profile etc" then try and tweak the difference from my driver settings if needed. OR if your printer seems to handle it, EPSON, recent inkjets in general SHOULD use the sRGB.... palette as your output profile. If when previewing printer profile (they're all hidden in one of the libraries - most likely user/library/color profiles) things were WAY different try to make up for difference in color settings part of driver. If the red had no punch then boost the magenta/ maybe yellow, boosting CMY increases saturation boosting black ink levels to same as CMY levels out sat. and puts more ink down across the board, "intensity" setting or similar usually boosts reds somewhat like contrast & brighten/darken when overdone on the high contrast side. NOTES ON ABOVE: This is one guys approach at the minute. It seems to work well so far, no big surprises and good saturation and color. Not perfect but I wish I had this to use a year or two ago. These are the basic steps toward (not complete I'm sure, OH YEAH use PERCEPTUAL pop-up when given the choice ANYWHERE unless you know otherwise (like printing exact spot colors etc). Anyway this gives a sort of quick summary to the color mgmt question from input to edit to output. VERY CRUDE if you know about these things but it should get you on the right track locationwise for settings and the general approach the different elements are using and giving you choices on etc. I used to wonder why the heck my printer printed that file well, and this file so BAD. Correct color somehow has more to do with perceived resolution than you might think. When colors are right, details and edges are crisp and have detail beyond seeable. If I have even one ink go out on the S9000 the print ALWAYS looks horrible. Seems rough, like bad source. NOPE not usually. OK I QUIT. Hope this helps. in getting the process going here. Sorry but the template thing isn't a great idea really, each file needs color mgmt individually to be maximized, but if you work around a single camera output ONLY. I guess it could work if scenario is like above, just be aware of what you're asking it to do. Is the template color managed? How? Should image file have same profile before copy? etc. Pasting into other is always a little dicey. Lots of questions there.... Scaling in Photoshop DOES NOT LOOK AS GOOD AS IMAGE SIZING then moving over by dragging if needed and color is cool.

The real nitty gritty though is this. Spend just a little time testing. Make a rainbow conglomerated high res image or find one. And print a zillion times with good full inks with different settings and write the settings down or even include in individual prints. You will actually SEE what the difference is. USE GOOD PAPER, USE QUALITY CAPTURE, WATCH YOUR COLOR SETTINGS, don't double convert on output to print etc. and TRY to shoot at 150 DPI to printer. Try higher but you'll probably find there's no visible difference AND it takes a zillion years to print (esp. on Epson, but of course the Epson SHOULD be able to do something with that data if any can.

AAAAAAAAHHHHHHH!!!!! I stepped into a can of worms, trying to give good info but SOOOOO MUCH to it. I truly hope you can see through the difficulty of writing instead of showing here and can get something from it in spite of the roughness etc. I've spenta zillion hours printing my art and designs and only hope that others could benefit also and find these things actually make a difference toward quality 99.9% of the time.

Self taught where the ink hits the highway one print at a time. DUH!

John_Reed
11-26-2004, 11:32 PM
Your opus seemed to diverge from the theme of your title? I print from a Mac OS X system, v. 10.3.6. To calibrate my monitor for printing on my Epson 2200 inkjet printer, I use a ColorVision "Spider" system, which hangs a physical sensor over the screen, subjects it to a spectrum of colors, and finally generates a printer profile, which is used by Apple ColorSync to ensure that the printed output matches the monitor display. I seem to get good results that way, I'm totally happy with the colors.

As for your statement about 150 dpi, I think I agree if you mean "pixels/inch." If I render any image about to be printed at 150 pixels/inch or higher, I can't see any jaggedies in the prints, no matter how hard I look. But my printer fills in each of those printed pixels at something like 1440 dpi, roughly 10 dots to span a single pixel.

I wonder if you might have some comments on interpolation? People always seem to calculate maximum print size from the image array size as issued by the camera. I say, since for a "Bayer matrix" sensor, the process of interpolation has already begun inside the camera, why stop there? As an example, the first 13X19 print I ever printed on my 2200 was of an image that began life as a 1600X1200 photo, saved at "standard" compression in my FZ1 camera, stored in a file of 317K bytes. To print a 13X19, I "cropped" it in Photoshop to the desired image size, at 160 pixels/inch. (Which it then created bicubically.) This works out to be ~6.3 megapixels, as printed. But the print looks quite sharp, great colors, no jaggedy edges, in fact a few visitors to my office actually bought FZ1 cameras after seeing it hanging on my wall there.

ZERO-D
11-29-2004, 04:16 AM
You are correct, way off from the title, oops. Renders it practically useless to most doesn't it? Oh well, as for your question about interpolation, why not? I mean I scale images WAY WAY WAY past anything intelligent and get great results. Right now I'm working on a tiny file I found in my browser cache ; ). It was about 2 inches by 3 inches on screen at 1600x1200. TINY! I used Extensis PixelSmart to raise it up to 24X30 inches @ 150 pixels inch. With this ridiculous amount of scaling of course you will lose little details. BUT if you're willing to go a little bit more abstract instead of purely photographic, you can make these look really cool at any size. The trick is applying effects subtly at this high resolution. It will make your fast old mac slow like the old days BUT, you can get some neat stuff. I use all the effects including plug-ins but usually I find myself messing with the artistic ones in Photoshop as a base. These are great because they attack the ugly stuff and turn it into high resolution rendered effect (watercolor, cutout, noise, darken edges, posterize edges, palette knife, etc.) I often run one effect and then make another layer of it and run it through another, or two and then tweak the color a little and use an apply mode on this layer to mix with 1st effected layer and/or the original in background layer. So there it is, my big trick. I can take a typical photo and scan or take a digital photo or whatever else you have and keep the subject recognizable (people for example) but stylized a bit. Often looks just like the photo from across the room but the closer you get the more like a roadmap, painting, sketch, or just weird texture it becomes. Up close it may look like the continents on earth from space or something,

Also: With a decent RIP or probably with just about any printer, you can scale right to the output size sometimes effectively. I've printed shots from my 8700 (Nikon) through PosterJet RIP software and printed 30"X40" with no effects just RAW camera image and had amazing results! This can be the easiest because if the RIP recognizes your cameras profile, you don't even have to sweat all that hash in Photoshop. It's going to get it right the first time. I get super saturated no jaggies beautiful images that people ooh and aah over. I mean just an extreme close-up of ice in a glass under neat lighting and printed out at like 3'X4' is amazing! You can see the little air veins in each cube and reflections of the glass on the liquid flowing over the cubes etc. I don't see any problem with the file being stretched. I think when most companies and reviewers etc. state those max image size kinds of things, they have a certain ideal in mind. They're staking their reputation on it and it is true that if you stay in the smaller non-stretched zones the image will have more crisp detail, BUT without a magnifying glass you won't actually SEE as much of the detail as if printed "TOO BIG". How about this for example. If you have an Epson ( I did this on my 880) in the driver control or print window, somewhere in there is a selection to print your image over multiple pieces of paper. You can choose up to 16 pieces of paper to render your image to. So the printer itself is taking one sixteenth of your image and blowing it up to full page size and doing a good job of it. YES it will be just a little more blurry etc than if printed on 1 piece, but you will get respectable results AND when you put it together and display it, NOONE will care at all. They will just be impressed at the size and detail of the image as it is. People are kind of used to it because any of those LARGE images you see (maybe retail posters etc) are more than likely stretched. I mean if an image is 6'X12' or something, you would have to capture at like 999Megapixels or scan at 15,000 dpi to actually do the correct process. Not many (if any) cameras or scanners can achieve this. So we rely on great software tools to make it happen.

NOTE: The biggest problem with scaling images is what I call the "panty ho" effect. When you stretch it, it gets lighter in color. Your bits of color are now stretched quite far. That's why you must get it back with some kind of saturation, contrast, image overlay, etc OR use software like the Extensis SmartScale that basically does just this. It doesn't do miracle work it just examines color levels and shapes or regions first, then reapplies that info at the new size so your "panty ho" effect stays in check. This phenomenon is most visible at print, not so much on screen. Print needs everything it can get.

OK I think I'm done. Literally, that's everything that I know, now go exploit it! Kidding, just notes from the road out here, telling it as I see it going down under the hood. Some color scientist would laugh but all I can say is that this stuff works, from print to print, day after day. No theory, just experience trying to make a decent big color print from inadequate source.

Oh yeah, one more thing, if your image isn't perfectly sharp and detailed, and scanned at print size. Then what have you to lose anyway? Not much! The perfect image is the one that needs the most respect in scaling and so fourth, Sharp detail is what stair steps etc. first in scaling. AND because the printer has the detail of your image at approximately 200% in Photoshop your printer will reveal the flaws which will be more apparent in a sharp image. Try it, preview at 200% in a 150dpi file then print at size, Now look at print and go back to 100% on screen, OK whatever, now go to 200%, if there are any little details or stray pixels visible at 200% on screen they will be visible in print and look junky. Lesser printers will throw this stuff out and the print will look more like 100%. Great printer will reveal the yuck in the file. So, oddly enough, a crappy image sent to a great printer will be worse looking than if sent to a crappy printer. Just like great speakers or any other high fidelity device. They will reveal the flaws NOT FIX. Seems counter to earlier stuff but not really. This stuff is more complex than I can explain I guess. If your printer was already going to reveal the flaws then who cares if bigger, you actually might blow them out. Most of the time these lesser images do OK in extreme scaling quite possibly because of this. You seem to blow ugly little details into softened blotches, then the use of effects can fix things up a bit. OK done. Wish I was more technical and could explain the whys more, but it doesn't really matter why if you take the time to learn around them and develop your style in response to these limitations etc.

I'll bow out on a weird fact about scaling here:
If you have a medium resolution image that can look decent (or not I guess) with an 8 bit palette, convert it to 8 bit then scale away. It will look the same if you keep it in 8 bit! If you had turned to RGB THEN scaled it would be blurry. But since the palette is limited, it can't add anything so it stays sharp to the pixel. For example you could make it out of paper squares printed as tiles for each pixel and put it on a building and it would be the same. Each "box" of color will enlarge with crisp tight edges. No blurryness in the scaling, just BIGGER boxes of color so more visible. Not a ton you can do with this but when you NEED it, here it is.

Hope I've confused some and inspired others. If you're inspired, good luck, and don't forget to play every day. It is essential, especially as you get older and have a tendency to forget. You can kill yourself taking it all too seriously.

D70FAN
11-29-2004, 09:32 AM
Hope I've confused some and inspired others. If you're inspired, good luck, and don't forget to play every day. It is essential, especially as you get older and have a tendency to forget. You can kill yourself taking it all too seriously.

Thanks for the tutorial. There were several interesting techniques that we probably all use, and it's nice to read confirmation from someone doing large format printing.

On the other hand there are several techniques that I have not tried, but plan to in the near future. I like learning something different. That's one of the great things about these boards.

Just one additional comment: You need to break your explanation points into separated text blocks as it is really a tough read (but worth it).

John_Reed
11-29-2004, 12:05 PM
Hope I've confused some and inspired others. If you're inspired, good luck, and don't forget to play every day. It is essential, especially as you get older and have a tendency to forget. You can kill yourself taking it all too seriously.Don't talk to me about old, kid! ;) Are you on Medicare yet? I just wanted to add to the "picture" that I've done two huge murals, one 5' X 14', and one 5' X 12', and both of them were rendered at 72 pixels/inch. I started with a large background panorama, and then overlaid a collage of snippets of various people and things on top. Sometimes the source was a little 3X5 photo, where I was scanning and clipping one person from a group, and then enlarging it bicubically through Photoshop. Still, despite the warnings of the (600 dpi) plotter guy ("It'll never look sharp enough"), both murals looked really sharp, and you have to look very close to see any "jaggedies" at all. And despite your "Panty Ho" effect, actually the colors came out fine, a bit over-saturated even.

wingsley
12-24-2004, 07:58 PM
There is an article in the current (Jan. 2005, p. 63) edition of MACWORLD magazine regarding pixels vs. printers. The article also appears on their web-site:

Picture Your Perfect Camera
Zoom in on the Features You Need and a Model You’ll Love to Use
By Derrick Story
How Many Pixels Do You Need?
http://www.macworld.com/2004/12/features/perfectcamera/index1.php

I was wondering what folks might think of this article. I can see it's one of those internet threads which, like the Energizer Bunny, keeps going and going and go.... :D

jaykinghorn
12-26-2004, 10:12 PM
I have compared inkjet printouts at various PPI and DPI resolutions and have the attendees at my printing seminars draw their own conclusions from the prints. There are a couple of important facts to consider when determining optimum image resolution for printing.
1) How many pixels do you have? I prefer to print at 200ppi with actual pixels instead of interpolating to 300ppi. Most of the Epson photographic printers do a great job of upsampling if need be.
2) What is the finished size of the print? The corollary to this is What is the expected viewing distance. You most definately can see a difference between a print with 300ppi vs 150ppi when looking at an 8x10 at arm's length. You can't discern a difference when looking at the image from 6 or 8 feet. The images used on billboards are often printed around 50ppi or less. If you plan to look at the image closely, you need more information than a print that will be framed and hung on a wall.

I would encourage you to do your own tests. Take an image and print it at 8x10 at 300, 240, 200, and 150 ppi. Examine the fine diagonal lines in your image closely. They are the first to show a loss of image quality. See what works best for you.

Happy printing.
Jay Kinghorn
RGB Imaging