Working with a 300dpi 4+gb file.

Thanks guys. Point proven. And yes its a huge wall 40 metres x 20 meters.

Let's take this from the beginning.

Are we really talking about 40 meters here? Not 4?

Anything above, say, 20 000 pixels long side would be considered a very large file, meaning you'd need a good, well-spec'ed desktop system to work. You can forget that on a laptop.

It would help if you could confirm the actual physical size, and the intended viewing distance. You don't need to step far back before the ppi requirement starts dropping fast.

If the image is intended to be seen as a whole, then you'd need to see it from very far away. In that case you don't need any more pixels than you would for a standard hand-held print, and the ppi could go as low as 5 or 10. It would still be seen as perfectly crisp and sharp, because it would occupy the same angle in your total field of vision. You'd effectively see the same thing.

That's not "unnecessary" - that's insane! That's 470 000 pixels by 235 000 pixels!

Who told you to use 300 ppi at that size? Don't ever listen to that person again. Ever. At that size, 15 ppi will give your system more than enough to work with.

Why do you need a 40 x 20 metre image to be 300pixels per inch?  300 ppi is normally used for viewing at book reading distance. A 40 metre image will usually be viewed from several metres away making such resolution unnecessary.

Dave