i have a 72 resolution picture 5440x 4250 which i want to print at 3m by 2 metres. (exhibition banner)
Can you list the steps i have to take in photoshop to make it happen? (Pls be very clear and step by step, please, talk about upsampling, leave resampling on or off)
At what distance will it be viewed?
The required resolution is based purely on the viewing distance and is based on the resolving power of the eye.
There is a formula to work out what ppi is required under perfect lighting and with good eyes for a given viewing distance in inches.
A normal viewing distance for a 3m x 2m (approx. 117 x 78) inch banner would be approx. 3.6 metres which is roughly 140 inches.
ppi = 1/((distance x .000291)/2) for your case that makes 49ppi. So the pixel size would be 5733 x3822. Your pixel dimensions are close enough to that number.
In short, unless this is to be viewed at an unusually short viewing distance, don't do any resizing. At a normal viewing distance - those pixel dimensions will work fine. If you want the rulers to work - just go to image size uncheck resample and type in the dimension in centimetres - You will need to crop the image to fit exactly 300cm x 200 cm