Large format printing DPI for billboards
Hi can anyone help my confusion?
I'm preparing artwork for some billboards - 96 sheets (overall size 12192mm x 3048mm). The specs say to produce artwork at a 10th of the size = 1219.2mm x 304.8mm.
HOWEVER the only DPI mentioned on the specs is 400 DPI which to me seems rather large for billboards - http://www.hi-rezz.co.uk/resources/UK/roadside%2096sheet.pdf
I'm trying to source some imagery for use (RF) and the maximum pixel size of these are around 5000px - whereas the pixel space I'm working with is 19,200 x 4,800px.
I've emailed the production company for confirmation but they've yet to get back to me.
In the meantime I'm wondering whether I'm being really silly?
I've never produced artwork as this scale before so it's possible I'm creating a muddle out of nothing.
Your maths is correct but remember that working at 400 ppi at 1:10 scale will give you 40 ppi final output, which sounds in the right sort of area for billboard printing, bearing in mind the distances they are generally viewed from.
I think you'll have a problem of sourcing images much bigger than 5000 px x 5000 px image, which is 25 megapixels.
But this will only be an issue if your 25 Mpx image stretches right across width of the billboard - is this what you're planning? If it fitted the vertical height, it would indeed be around 400ppi.