Resolution for large photo sign

In my experience 50 dpi is acceptable for banners 75 is okay.

 

4320 x 2592 will get you a resolution of 72 dpi. At that height and size it should look fine. Essentially any image from a modern cell phone or digital camera will be more than enough.

 

Agree here. Make sure it's the original and not snagged off facebook or passed through many hands with their own little photoshop/photopaint trickery applied.. Facebook downsamples photos.

 

Believe it or not, 50–75ppi is actually a lot more than you really need in this case. The further the viewing distance, the less pixels you need. A sign seen from 30 feet away would only need to be around 20ppi for the image to look good.

Here's the formula:
600 / viewing distance (feet) = minimum resolution (ppi)
i.e. 600 / 30 ft = 20 ppi

And hopefully I don't need to do the rest of the math for you, but 60"W x 36"H @ 20ppi = 1200x720 pixels. Note that if you were to print a 1200x720 pixel image on this sign, you will see square pixels clearly in the print before you install it, since each pixel will be 1/20 of an inch.

 

36 dpi works great with me.

 

http://www.oliver2255.com/Wisconsin/Most08/2150fwa.JPG