I have a project where I need to make a large poster. I'm not sure what the final print size, but imagine a movie poster around 24x36. When I go into PS to create a new document, I entered the dimensions of 24x36 at 600ppi, CMYK at 16 bit....and the file size is 2 gigs. That seems like an unmanageable file size so I am curious of what I should do. Should I do 600dpi and 16 bit for safety, what about size, can I stat smaller and then resize it later? Most of the poster will be text, but there are several photos and bright colors.
It really depends on the device that your going to output to that determines the DPI. 600 in any case is over kill. 16 bit is also over kill for mostly text. 8 bit is usually always good enough unless at this size you have huge continous tones or are outputting to say 200 lpi (lines per inch) Which you are probably not doing. Any CMYK printed piece doesn't need to be more than 300dpi especially since most is text as you say.
No you can't make it smaller now and size it up later. When ever your dealing with raster images (like a PS file) you can always go down BUT NEVER up.
With a poster this size your probably out sourcing it to a company to print it. Call them and ask them for their specs. Some output devices companies use may require RGB files, and sometimes only 100dpi. Their RIP software takes it from there. Most high end output devices today do much better in RGB. Now with that said, if your going to offset press, then yes, CMYK.
Whenever you are having anyone else print something for you, ALWAYs confide in them first in how to set up the job BEFORE you even start.
Hope this helps.
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