2 Replies Latest reply on Jun 20, 2013 4:13 AM by Peter Spier

    creating hi-res pdf files

    Danilib126

      when creating a hi-res pdf file, i use the option of "bicubic downsampling to 300dpi for images above 450dpi" - if this is turned off, do you get a better end result, specifically when printing to billboard size?

        • 1. Re: creating hi-res pdf files
          Eugene Tyson Adobe Community Professional & MVP

          300 DPI is a rounded up figure for lithographic printing, where they should be multiplying the LPI of the device by 1.41 to get the DPI - that is if the imaging device has a LPI (lines per inch) of 150 then the DPI for an image should be approx 211.5 DPI.

           

          Most people multiply the LPI x 2 to get the DPI - which is errouneous - hence multiplying 150LPI x 2  = 300 DPI.

           

          But certainly if the device is 175 LPI * 1.5 = 262.5 or if it's 200LPI*x1.5 - 300

           

          So 300 is a safe bet for a lot of lithographic printing.

           

           

          Different lithogrpahic purposes use different LPIs - newspapers use about 80 - 120 LPI as the paper is pourous and can't absorb too much ink - if they ran at 150LPI on that type of paper the ink would never dry into the paper it would sit on top of it.

           

          For newspapers you'd use between 120-180 DPI for your images.

           

           

          With Billboards the equation is completely different - it's based on viewing distance!

           

           

          Certainly for a bill board 300 PPI is way too much - you could get away with 40 PPI or even 72 PPI or even 150 PPI

           

           

           

          Your print provider should be giving you details on what the size and resolution of the images should be before going to print.

           

           

          However - when I'm sending large format files to the Printers for the purpose of large signs I turn off Compression altogether!

           

          There's really no need to compress them - there's no reason to Downsample them.

           

           

          You get a HUGE file - but with services like "we transfer" and "dropbox" "drive" and other cloud based file transfer system sending and receiivng large files is a cinch.

          • 2. Re: creating hi-res pdf files
            Peter Spier Most Valuable Participant (Moderator)

            For billboards I think you're really talking about pixels per foot or per meter, rahter than per inch, but that's at print size. Without knowing how big the ID file is and how much it's going to be scaled I wouldn't want to give a figure for resolution in the file.