I have made an A4 size poster using Photoshop. But I want to take a 2-3 feet size printout. So, do I need to scale the poster to appropriate size or the press can print any size of poster using same file without loosing the quality?
Am not expert and have no good experience in poster printing/designing but i'll write down what i think.
If your poster is in vector format then there wont be any quality loss even if stretched out.
If its in bitmap format then it will depend on the resolution. Typically i send my printing works at 300 dpi (small ones) so if your poster is to be enlarged then i think you will have to increase the dpi so that after resize the pic can still be at 300dpi.
then how is the 10feet by 15 feet hordings done in photoshop? or are they using different software. I can only image the RAM we will need and the size of the image if we define our picture as the real size in photoshop.