Trying to get a poster made and want to triple check my stuff before I go having it made. Not going through a website but a local shipping place near me that can do custom prints. Can get HUGE pictures done up to I think 36" width by however many lengths I want it so pretty dang big.

Problem:

I'm reading different articles talking about conversion of pixels into inches where it isn't exact. They also say that the DPI can increase the pixel width/height which confuses me even more. Photoshop tells me a 24" width by 36" Height is roughly 14400 pixels width by 21600 pixels in height at 600 dpsi which seems a bit extreme. This is contradicted by another article I read saying 3400x5800 should produce an ok image at the mentioned 24" width by 36" height. Final problem is dealing with posters who say anything past 300 dpi doesn't really mater as we humans can't tell a difference beyond that it looks all the same.



Kind of svcks being a photographer and getting confused by this but I just need some clarification by some tech savvy people.

Dunno if Photoshop embeds DPI information in their images, if it does then a professional printer will read that and print according to that to maintain the desired clarity. Otherwise, yes, it is possible to mess with the dot density and make an image smaller or bigger. There is no set dot density.

600 dpi will give you a really nice photo-like quality to your print, although anything in the 300-600 dpi should suffice for most needs (preferably higher depending on how big you're printing.) Some really high-quality prints go as far as 1200 dpi, but that's more for pieces which will be under incredibly close scrutiny. Ultimately it comes down to the density of "dots" of color/shading information, and the more dots there are the closer the shades will match the original image... I'd say 600 dpi is probably good enough for your needs.