Uprezzing to 48" x 32" for poster background in PS CS4

[PSA DC-9-30]

I have a 2560 x 1707 8-bit grayscale .tif  that I want to use as a background for a 48" x 32" poster. Since it will be used as a background with text and other images covering much of it, I think 150 ppi or so should suffice--e.g., 7200 x 4800 px (opinions?). I also do not want to end up with an enormous filesize because there are numerous other images on the poster.

I would like to ask how to best upres and post-process such an image in PS CS4, from its original state so it will look good at 48" x 32". Should up-rezzing be the first step before curves, noise reduction, sharpening, etc?

Thanks,
Kevin

[Richowens]

Kevin,

 Do all your processing first except output sharpening, resize and output sharpen.

 If you are compositing this with other photos and text, everything will have to be the same PPI,color mode and bit depth.
 
 Once you lay all your photos and text on it you can flatten the layers and you will be back at the original file size.

Rich

[LoisWakeman]

Try Qimage from DDI Software. It is very good at this sort of application.