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Producing a file for billboard printing

Discussion in 'Printing & Print Design Forum:' started by Melmoth71, Oct 10, 2013.

  1. Melmoth71

    Melmoth71 New Member

    Hi all, I could definitely use some help with a printing issue.

    I have won a commission for one of my black and white photos to be printed as a large (28 x10.5 metres) banner and placed on the facade of a large arts organisation, so I'm over the moon with excitement but there seems to be a problem with the printing process.

    The file for the printing company is being produced by a volunteer graphic designer but neither he nor the arts organisation are experts at producing images for billboards/banners and I have no experience whatsoever of this sort of thing, so we seem to be lost at the moment and I'm terrified of losing this opportunity.

    The problem is that theprinting company is telling us that when the original image is blownup to the size required for the printing, the quality is not goodenough. The graphic designer has used Photoshop and Perfect Resize toblow up the image. The printing company's team have also produced anenlargement they say is not good enough.

    My original (monochrome) file (resized to fit the banner's proportions) is from my Nikon D60 DSLR at maximum res, it's 3872x1450 pixels big. The designer says the image has to be blown up to 16535 pixels wide which he hasn't managed to do with the required quality.

    I came up with the idea of printing my photo with the best quality possible (maybe as a 12x4inch print), then scanning the print with a high-res scanner to produce a much larger file. Would this be possible?? Would it produce a good enough image?What other options are there?

    Any help would be hugely appreciated. The arts organisation wants to get the printing done as soon as possible.

    Thanks a million inadvance.

    Miguel
     
  2. Paul Murray

    Paul Murray Moderator Staff Member

    I'm probably not the best person to answer this, since I have no experience of producing artwork for a billboard, but I'll throw in an idea.

    Since the image is black and white you could potentially blow the image up to the size you want in Photoshop, then convert it to a 150dpi fine halftone bitmap image, save that in a printable format and send it over. Since it's being viewed from a distance and the image is black and white this could work, providing the designer's computer doesn't explode when he tries to create the bitmap though. It can cause a system to slow down and hang even at smaller sizes.
     
    Melmoth71 likes this.
  3. hankscorpio

    hankscorpio Moderator Staff Member

    Billboards don't need to be 150ppi - that's way overkill.

    50ppi would be enough or even as low as 30ppi.


    This is a distance formula I came across (sorry I don't remember the source) - seems to work well for what I've done.

    It's a little scary - but because we're working in Pixels Per Inch - it's easier to use Inches as the Distance away.

    (working in inches)

    1/((distance x 0.000291) / 2) = ppi




    For example, if you're viewing from 20 feet away (240 inches)


    You need


    1/((240 x 0.000291) / 2) = 28.6 ppi for final size (absolute minimum! try have it larger)



    And the other contributor to the forums is absolutely correct.


    For black and white photography you may be able to go a little wilder with your resolution and have it even lower.


    And guess what, if you've got soft images (like water, clouds, sky, grass etc.) then you can go even lower than the recommended.

    And guess what - if you have sharp edges, corners, people's faces etc. - then going below the recommended PPI is not recommened! In fact try to keep that well above the recommended.


    Hope that helps.
     
    Melmoth71 likes this.
  4. Melmoth71

    Melmoth71 New Member

    Thank you very much for this! They are actually asking for 15ppi. The problem is that when we blow up my image to make it big enough to reach that figure the printing company say the image quality becomes too low, that's what I don't know what to do about.
     
  5. Your file unedited has pixels 7mm square when run 28m wide. Your designer is saying you need pixels 1.7mm square. (your file gives 3.5ppi, your designer says you need 15ppi)

    Working that very useful formula backwards, 15ppi suggests a viewing distance of 38feet. (presumably before you can discern pixels.) I question whether you can make out a 1.7mm pixel from 38 feet away. (Please do check my maths, it's a long time since I did any algebra!)

    As is always the case, it's about managing expectations. If the client wants this to look like a photograph from 3 paces back, forget it. Even from the other side of a street you're probably pushing it. But there's one sure fire way of telling. Get a 1mx1m chunk printed from the original, and the same again from the best interpolated file you've come up with. If someone is about to print you a £2K banner the least they can do is help you understand what you're getting, and manage the client expectation for you. If they won't, get them to give me a yell, it's been a while since I've run one that big!
     
    Melmoth71 likes this.
  6. Melmoth71

    Melmoth71 New Member

    Thank you very much for your comments which were very helpful! Thanks hankscorpio for the formula which was a great help. Luckily the crisis was resolved (the printing company accepted the enlargement we produced) and the commission is to go ahead :)
     

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