I am a student trying to create collages in Photoshop sized* 4' x 4' and larger, resolution 300dpi, to be digitally printed on cotton canvas and silk.
The enormous file size causes my iMac to lag or freeze. Many times the files will not save at all. I'm new working at these dimensions using Photoshop and came up with few solutions myself.
I have tried to work on the prints in smaller pieces and puzzle them together, but the results haven't been satisfactory. The only other option i have come up with is to lower the resolution, but that the printer has advised me that printing lower than 300dpi will adversely effect my final product.
*) 4 ft = 121.92 cm
How close are you going to view the 4' canvas?
Is reducing the dpi really going to adversely affect printing on a coarse material like cotton or silk. Thats coarse relative to smooth glossy photo prints, for example.
See this recent question: What resolution should a large format artwork for print be?