I have started the long process of editing, and decision making as to what images are to be printed. My current thinking is to go for 7 A0 prints from Whitewall. I will need a bank loan… My initial thought was for 5 images. However, I have seven sets of people. I need to think long and hard about this. I am instinctively reluctant to “discard” people… but I may have to. we shall talk, and seek other thoughts.
I have been assigned a display area. I am in Uni tomorrow, so it will be a good opportunity to measure the space, and see how many prints the space will accommodate.
If I go to A0 size, I need to upscale the image size. What is immediately apparent is that at A0 size, file size will become an issue as upload speeds become a problem.
As usual the internet has a mountain of useless information. Scott Kelby in his book on Photoshop offers a solution to going to “poster size.” However that involves increasing the resolution to 370dpi. That is all well and good, but the file size is huge. 750MB huge… so not a solution.
The key here is “dpi.” What is the appropriate dpi to use, at the nominal viewing distance for an A0 size image.
This page, found after much hunting seems to offer the most sensible, and understandable advice.
So to pull some observations from his page.
Pixels per inch and what you can see
The human visual system has a good, but limited resolution. This means that beyond a certain level of detail there is nothing much to be gained by ever higher resolution images.
The point is that this trade-off occurs depends on how far your eyes are away from the print.
At a recent trade show, where some of my black and white prints were on display, someone (you know the sort 😉 came up, pressed his nose close and declared that my prints were “over sharpened”
Fine, they were — for a 6 inch viewing distance!
As I pointed out, I don’t tend to do 26″x17″ prints for people to view from less than a foot away. It’s why billboard posters can make do with 10ppi. So for prints bigger than A2, I’ll typically use 240ppi, and for the two big prints I used 180 ppi. That doesn’t mean that if the camera file had sufficient detail to print at higher ppi, I wouldn’t use it, it’s just that if I’m resizing an image to make a big print, then there is no need to take the interpolation too far.
On reflection then I should be able to get away comfortable with 150-200 dpi for the A0 images. I need to remember to sharpen for the viewing distance, and not from six inches.
My viewing formula is 1.5 x Diagonal of the printed image.