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Participant
September 20, 2017
Answered

DPI OR PPI

  • September 20, 2017
  • 2 replies
  • 3466 views

I have been making a poster for someone and now that I am done with the poster, they said that they want me to export the poster do that it is PDF at 300 DPI. When I go to export settings to check that it is 300 DPI, it says :

Is this right?

This topic has been closed for replies.
Correct answer Mario Arizmendi

Maybe this article helps you to understand better...

PPI vs. DPI: what's the difference?

2 replies

Mario Arizmendi
Mario ArizmendiCorrect answer
Legend
September 20, 2017

Maybe this article helps you to understand better...

PPI vs. DPI: what's the difference?

Mike_Gondek10189183
Community Expert
Community Expert
September 20, 2017

True that DPI refers to the amount of dots in a printer, but that refers to desktop printers, rather than printing presses which use plates.

The article leaves out LPI which is also a printing measurement of dots, but the dots are created by halftones. For optimal quality you need atleast 2x the pixels for the lpi. So for 150lpi (most common in lithography), you need a 300 dpi image to get the best quality out of your printing plates.

JETalmage
Inspiring
September 20, 2017

For optimal quality you need atleast 2x the pixels for the lpi.

The rule of thumb is 1-to-2 times the halftone ruling. 300 ppi is not an "at least" minimum.

JET

Legend
September 20, 2017

For your purposes, and your printer's, and mine, ppi and dpi are the same. Some people get very addressed about the difference but I couldn't care less until someone shows me a job which messed up from mixing the terms. I think they're just showing off.

Participant
September 20, 2017

Ok thank you. This is the first client job that I have had, so I want to make sure before I send them the file.

Legend
September 20, 2017

It is worth noting though that the resolution they are quoting really only applies to images in the file (eg photos) And your setting has no effect on this: you need to be aware and set image resolution accordingly. Your vector work remains vector on PDF.