If I change a photo DPI from 72 to 300 will photo be ready to be printed as a poster 50 cm x 70 cm?

Question

I have photos in 72 DPI and I want to make a poster 50 cm x 70 cm. I read that 300 dpi is needed for printing poster. I changed dpi in Photoshop from 72 to 300. Is that guarantee that poster will be printed well?

Answer 1

DPI means dots per inch.



How many dots (pixels) do you have on your photo?



Let's see ... 50CM is 19.5 inches (+/-) and 70CM is 27.5 inches.



So to print at 19 X 27 at 300 DPI you would need a source photo that is

19 X 300 = 5700 pixels wide

27 X 300 = 8100 pixels wide



5700 X 8100 = 46,170,000 pixels or 46MP



So unless you shot that photo on a 27,000$ digital medium format camera like the Hasselblad H5D-50 you are out of luck.



1- Whoever told you 300 DPI is needed for a poster is an idiot.

300 DPI is for things like flyers or magazines ... not for posters. Posters can be printed at a much smaller DPI ... the further away you are from the print, the smaller the DPI can be. Billboards are printed at around 30-40 DPI.



2- Odds are, you stole a photo online and want to print it ...

a- That's not gonna work at those sizes since your source file is probably 600 pixels at the long side at most. The largest you could prints such a small file at would be 4X6 and the quality wouldn't be very good.

b- Unless you own the RIGHTS to that image, you are committing a crime.

Answer 2

Are you printing this on your own printer? If you're sending it to a lab, forget about the dpi. They will adjust it for their printers. The important figure is the absolute pixel dimensions. You haven't given us that figure, so nobody can tell you if your image will be presentable at the dimensions that you desire.



One other thing, the 300 dpi figure is often quoted as the desirable resolution for a print. Few realize that it depends more on the viewing distance. Anything down to 250 will be okay if viewed from a reading distance. Large prints are meant to be viewed from a greater distance. So the dpi can be lower. Want proof? Walk up to a billboard and view it from a reading distance. You might be surprised at how bad the resolution is.

Answer 3

I'm afraid not buddy, Enlarging the DPI in photoshop is never a GUARANTEE that the resulting image will be flawless for print. It depends also on the original dimensions of the photo, but generally, upscaling from 72 to 300 will only make it huge and grainier.

Answer 4

You need to tell us the dimensions of your image in pixels, not cm.



There is no way to tell how large you can print it otherwise.



The dpi is not the image resolution!!!! On it's own it tells you nothing about the quality of an image.



300dpi is not required for printing posters either - as Eric has said, only an idiot would suggest that.