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Large format printing.. help please

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  • Large format printing.. help please

    I am student and am very intreseted in designing related work.
    I am facing a problem.

    Making a design for an A4 is easy as we get images which come out well on them in printing. But when i try to design a banner, all my prints come out horribly. I hope you could tell me what should be kept in mind so that such mistakes do not happen.

    Prob: i am designing a indoor display of size 20 ft by 15 ft. i want to put a image that would occupy nearly the full banner, the image i have in my hand is 300 dpi with 7in by 5in dimesions. It is a graphic and not a vector. The banner will be viewed from not more than 2 ft distance. It has to be put in a gallery leading to cafeteria.
    Please .. please help

  • #2

    you have a problem there. We print large format and we ask all files to be at least 600DPI at 1/10th scaling. This I find is the best "bang" for the buck when it comes to quatlity vs. file size.


    • #3
      Yuh, that would be a big problem.

      Do you understand image resolution and how it relates to scale?
      You have a 7" image and you want it to be 240".
      divide 240 by 7
      You get 34 and change.
      Now divide 300 by 34.
      Your resolution is almost 9dpi.
      That might look good - from across a parking lot. Even billboards are run at 20dpi (+/-) and that's 6 seconds at 60mph, not arm's distance while walking.

      Now, your going to say, but I told Photoshop to keep it at 300dpi while making it bigger... Photoshop is a wonderful program but it just can't create something that isn't there to begin with. Please see

      There is not much you are going to be doing with that image. It's hard, but not impossible, to find images that can go that large (though it is getting harder and more expensive every day). You will probably have to pay for them though. Image release rights on a mural sized, semi-permanent installation can run you quite a chunk of change (I just paid over $1200 to Corbis for one). If your image is a client requested one-of-a-kind, you are hosed. The biggest you might get that thing is 42" x 30" (50dpi). It won't be pretty from less than 5 or 10 feet though...
      Last edited by PrintDriver; 03-22-2006, 08:24 PM.


      • #4
        You can do this but, its a bit more complicated.

        As we all know you can not increase image size on the computer without lose in resolution.

        So what we can do is make up for that lose when resized.

        First off, what you need to do is get the highest quality print of the image.

        Next we put the caling factor into effect:


        a= origional dimensions (5 x 7)
        b= new dimensions (180 x 240)

        *Since, 12 inches are in one foot and we need the measurements to stay consistent.*

        c= output resolution.

        Now i am not sure on the output res of something that large, but someone should know. However this is the usual thinking:

        web= 72 dpi
        digital = 150 dpi+
        offset = 300 dpi+

        So lets say your printing for press at 300 dpi- which i don't think is the case because when you print so large the dpi becomes less then what its "normally" at. However, i could be wrong and printing it in 300 dpi would be fine. We are going to go with 300 dpi for example purposes.

        What you need to do first is find a proportionate resize:

        Does 5 go into 240?

        Does 7 go into?

        Ok... one second I'm confusssing myself I usually work these things up on paper. first- as I just did this for a friend a couple weeks back for a screen set- but let me work it up first.

        This can be done its just going to take a scanner and a very good computer cause in order to make up for the resize the initially image will need to be scanned in at some outragous reslution(which i need to work out doing the math).

        The promblem that will arise is that you may end up needing to scan in this image at some outragous dpi like 5000. If that is the case then the cpu will most likly crash and die which will not be good.

        So worsth case scenerio is you may need to go through these steps afew different time resizing a bit at a time so you can get to the largest size able to fit on scanner bed. Even then though… the cmputer still may need to scan it in at some outragous number- so lets hope not.

        Anyway i'll work it out really quick and tell you waht i have.

        I'll work it up in illy so i can show you exactly whats happening.


        • #5
          It's already a digital image. 5" x 7" @ 300dpi.

          If it is a 5" x 7" walmart developed photo print from a film negative (even a slow one) you aren't going to be able to take it up large because the grain will show after about, oh, 48". Usually less.

          If you want to scan a 5" x 7" photo print from a film negative to make this mural size, which the printer will print somewhere between 50dpi and 100dpi depending on several factors, you have to scan at 3600dpi to allow for the 15' dimension and crop to the 20' dimension at 100dpi (1800 for 50). So it isn't astronomical. Unwieldy but not undoable.

          If you want to scan the negative itself it better be darn slow film and you gotta know someone with a drum scanner because you are gonna have to scan that little puppy at over over 10,000dpi.

          Now, if this is a digital image and you take it to walmart to print on their Kodak do-it-yourself (or even if you have them send it out for processing) you still have a digital image made up of dithered ink (high quality inkjet) or pixels (laser exposed).
          You scan that, you'll end up with bigger dithers or bigger pixels (sometimes a blurry mess too). We've even tried writing to film using a digital film writer with very little success.
          Last edited by PrintDriver; 03-22-2006, 09:05 PM.


          • #6
            I forgot to mention that scanning that image at 3600dpi makes a file over 1.5gigs. Printers hate that. At this size we would probably run at around 50 to 75 final, depending on the machine used so the file size stays under a gig.

            And that's a real round about way of saying what Jeff said right at the beginning. 600 at 1/10 scale.
            60dpi final.

            tZ, most standard flatbeds won't scan above 600dpi without interpolating. The scanner driver doesn't even tell you it's doing it. You have to know the limitations of your equipment. How did your friend's screen turn out?
            Last edited by PrintDriver; 03-22-2006, 09:15 PM.


            • #7
              Ok here is some math for you (orig poster)

              Ok so basically you need to scan the initially image in at 10,800 dpi which I don't think is possible.

              So what you may be able to do is first resize the image to that of the scan bed the try. However, unless you can find someone who is capable at scanning in your image at around 10,000 its not possible because of technological limitations.

              Even if you were to blow the image up to 21 in x 15 in and print then rescan for the image resize i still don't think that would be possible either. You would still need to scan the design in at least 5000 dpi which i don't think any printer or computer for fact is capable in doing- sorry.

              Print driver: it wasn't this large of a resize. It was about an 11 x 14 to a bit more then 2 x 3 ft. However, the logic remians mostly the same without the technological limitations.

              I heard you say the printer would print this at around 50 to 100 dpi deopending so is it safe to say that the initial poster could scan in at:

              36 x 50= 1800 dpi

              or better yet:

              36 x 100= 3600 dpi

              Because wouldn't those be possible? or would a scanner not be able to do that either?
              Last edited by tZ; 03-22-2006, 09:29 PM.


              • #8
                Non the less, this is that math:

                I'm not quite sure if this would work, you should prombly check with your printer.

                You should also see how much it would cost to print the design initially at the samller sizes for rescan.

                hope that helps.


                • #9
                  thank you guys..
                  It really removes a lot of confusion from my head and gives me much more clarity.

                  I will try out work that with my design and see how it comes out finally.

                  @Print Driver
                  Thank you for your advice

                  @ jeffr0wland
                  thanks for the information

                  ps. This forum is better than others and YOU GUYZ ROCK!!!! I will be visiting this more and more often now.


                  • #10
                    tZ, there are flatbeds out there that scan uninterpolated to 4000dpi.
                    Most people won't put paper into a drum scanner. Usually negatives or CTs only (if paper comes loose you can ruin a $60K piece of equipment in the blink of an eye).

                    I'm telling you though, while it seems logical, scanning a print made from a digital photo is only asking for heartbreak. I had one happen just last week. Designer sent me what appeared to be an 8" x 10" glossy print. We scanned it and ran a full res print test and guess what. Lots of little 1/4" squares turned up at final size... Turns out the designer had a digital camera photo printed on a cont-tone printer... Can't trust anyone these days! Getting the squares was odd. Usually they just come out blurry. Really blurry. Gotta start carrying a loupe with me. LOL!

                    As for final resolution...
                    Last edited by PrintDriver; 03-24-2006, 07:32 AM.


                    • #11
                      wow, this could get confusing. I just came up with ours by running a full day of test prints. Most commercial large format stuff we do never gets looked at any closer than 2-3 foot.

                      Printdriver, I got a feeling you gonna be the #1 person I post to the most.


                      • #12
                        Have you looked into using genuine fractals:


                        we have used this in the past with great success with it.
                        GDF Users Get 20% off at
                        On Printing, Scanning, Mounting, Laminating, and More.


                        • #13
                          Even Fractals can't make a silk purse out of a sow's ear. This is one mighty big jump from 9dpi to at least 50dpi for an arm's distance mural. Even Fractals is not going to be making this look good.


                          • #14
                            I agree with PrintDriver. The pict you have is too small for what you want to do. And any way you slice it, a photo which would give the correct quality is gonna cost, one way or another.

                            By the way, PD, wouldn't the best way to do this be to have shot the photo with, oh, say large format film (or maybe one of the newet Phase One 36mb digital cameras-which I'm sure cost a butt load of $$$) and drum scan the film. Even 35mm film has limits (as you said) on how small the silver gel can get (sorry if that's not the right term for the light-sensitive solution, it's been 9 years or so since I took Photography).
                            I'll double check your spelling if you'll double check mine. Two heads are better than one.


                            • #15
                              You can only use a Phase One if there is nothing moving in the image. They take a long time to process and are best used for composed still life type things.

                              35mm can only go so large before you start to see film grain (<the term you were looking for). The slower the film the smaller the grain, the larger you can go. Same holds true for 35mm negatives. I can't go much larger than 11" x 17" in anything over 400 speed film.

                              I always recommend 4" CT and drum scanning. 8" (and a very steady, accurate-focus photographer) if you want very fine detail, say for a reproduction of a map into a mural. You will be limited by your printer's willingness to print something this large at high resolution though. Some printers only want 35dpi for large stuff, some will take up to 100dpi, file size permitting. As I said before, a 100dpi file is over 1.6gigs flattened. Most large format printers will look at you sideways if you hand them that. You're likely to pay extra if you insist.






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