Contest requirements confusion: pixels vs. DPI

Started 2 months ago | Questions thread
NAwlins Contrarian Veteran Member • Posts: 3,571
Stupid requirement but easy to follow
3

I'd soon like to enter my first photo contest, but their requirements confuse me a bit:

They want a JPEG image, one side of which needs to be at least 4500 pixels, and its DPI needs to be 300. The winners' photos will be displayed either on a screen or printed at 50 cm x 75 cm or 100 cm x 150 cm.

I know it's possible to change a photo's DPI value without changing its size in pixels.

So, is that really all they want? A garden-variety 72 DPI, (for example) 6240x4160 pixel photo whose DPI has been changed to 300?

Yes, I think so.

If you edit the file that comes out of the camera, just set it to 300 ppi (incorrectly called dpi by Windows and some other software*) before or when you export the edited file as the JPEG you will submit. If you are submitting a straight-out-of-the-camera JPEG, then check the file's EXIF data, and make sure it's set to 300--again, Widows called it dpi, but it's actually ppi.

This is a stupid, or at least poorly-expressed, requirement from the contest. They ought to say it something like, 'at least 4500x3000 pixels' or whatever. The DPI or even PPI part is needlessly confusing.

*DPI or dpi = dots per inch, and pertains to how inkjet printers spray ink droplets and how certain commercial printing works. PPI or ppi = pixels per inch, and is the correct term to describe the resolution of an image.

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