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Andy_777
Participating Frequently
April 30, 2019
Question

A0 print correct resolution & size for print

  • April 30, 2019
  • 2 replies
  • 20002 views

Im trying to design an A0 poster that will be digitally printed. I have a photo that will fill the whole poster and was taken in RAW format.

I can save it out from photoshop as a PNG file at A0 size of 841 x 1189 mm and 300PPI.

Next I set up my Illustrator file of 841 x 1189 mm with 300DPI and this is where I will place the photo and other elements for the poster. Im using Ilustrator as Im using familiar with it for layout.

The problem is that when I place the PNG into the illustartor file its tiny. I know its something to do with the fact that the image is in ppi and the illustrator file in in dpi but I cant figure out the solution that will ensure my PNG from RAW is the right size and res for an A0 print (300dpi outputted as high res pdf for digital print)

Am I going about this the wrong way,  can anyone please suggest the correct approach?

Thanks in advance

    2 replies

    D Fosse
    Community Expert
    D FosseCommunity Expert
    Community Expert
    April 30, 2019

    Absolutely. Don't use PNG for this. PNG is strictly a web format for screen use.

    Pixels per inch (ppi) is the correct term. People sometimes erroneously use "dots per inch" (dpi) which refers to printer output, an entirely different matter. In this case both should correctly be referred to as ppi.

    To print a raster file at 841 x 1189 mm, at 300 ppi, the document needs to be 9933 x 14043 pixels. That's a huge file! Do you have a Photoshop file of that size? I'm guessing not. What are the pixel dimensions of your Photoshop document? You can't just "save it out" to that size, as you seem to assume. You need to have that huge file to begin with.

    Also, you probably don't need 300ppi. That print always needs 300ppi is a myth and a misunderstanding. It depends on the viewing distance. You'd probably do splendidly with 100 or 120 here.

      A
      Andy_777Author
      Participating Frequently
      April 30, 2019

      The RAW file import size is 4288 x 2848 pixels at 300ppi (see below)

      What is the best way to increase this file for printing at A0? I will stil need to place into illustartor to add my vector elements etc and Im assuming i wil need to make this illustrator 9933 x 14043 pixels at 120ppi....does that sound good? thanks

      D Fosse
      Community Expert
      D FosseCommunity Expert
      Community Expert
      April 30, 2019

      Don't scale up at all, unless it's absolutely necessary to avoid visible pixels. Upsampling (as it's called) never improves a file, but can very easily ruin it if you're not extremely careful.

      Open Image Size and set the print size with "Resample Image" unchecked. That leaves your file unchanged, the pixel number stays the same. The ppi number, however, will change according to the size set. The bigger you print, the more the ppi number drops. Remember, pixels per inch.

      So set your size, and see what ppi you end up with at that size. It should be slighly less than 100, which should work well at a realistic viewing distance.

      Resampling just invents pixels where there aren't any. It doesn't add any detail, it doesn't improve the image. But it does alter the pixel structure. If you absolutely have to upsample, if the ppi number drops lower than acceptable, don't overdo it. Again, you don't need 300 ppi here. That's massive overkill. Anything above 120 is completely wasted.

      c.pfaffenbichler
      Community Expert
      c.pfaffenbichlerCommunity Expert
      Community Expert
      April 30, 2019

      I can save it out from photoshop as a PNG file at A0 size of 841 x 1189 mm and 300PPI.

      Why png?

      That format effectively has no place in print related production.

      You should use rather a format like tif or psd.

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