What? Its not obvious to you?
No becacuse you're the only person thats ever opened more than on layer in photoshop. Layers, are one of the least efficeint ways to image process, but its The Industry Standard, so it must be good, right?
Eh, what? Really, have you ever had to do much work on any photographs in Photoshop? Non-destructive editing of images is vital when you're fine-tuning a photograph, and layers allows that. Yes, it's the industry standard with all that implies, but that doesn't exactly make it a bad thing either. It's industry standard to provide USB sockets on motherboards - is that a bad thing? Besides, many many years ago, TV Paint was the first application I ever used with layers in it. It was limited to 3 layers, but I found it was amazingly flexible, and quickly got frustrated with having to merge layers to free up another one, only to wish I hadn't because I want to edit something on one of the merged layers.
Professional magazine photographers have been opening up images in photoshop for more than 10 years with a fraction of the RAM. I'm convinced that most shots are taken at higher resolutions than needed, just beascsue they can. I have a digital publishing and design graphics magazine from 2000. 3 Megapixels cameras were the next big thing. Now they'll shoot the same photo at 12 megapixels, and complain they don't have enough ram in Photoshop to open it .
It really depends on what you want the image for. High-quality prints need 300dpi at least, so all you have to do is multiply this up to what size you want and that's the amount of pixels you need. It's not rocket science, but why not deal in the highest number of pixels you can, in case you do end up wanting to print it poster sized? And why not have several layers so you can adjust your curves and go back later on if you feel after you've printed it that you've lost some detail, and readjust? It's unfortunate, but layers are just that - layers, including however many million pixels of information. It's a large amount of information which is incomparable to an encyclopaedia, and there's no way to get away from it. Pure, raw information.
In 1998, my school was using G3 imac with firewire to do all that shit-with about a tenth of the hardware specs. You only think we've come a long way..
Have you tried watching a youtube video on a G3 Mac recently? Yes, I'm not defending the programmers of these things who are producing massively inefficient code, but some things in the modern world do actually need more CPU power and memory, like it or not.
