Are there guidelines on how much memory a computer needs for large image files?

[newmoon2night]

I've just been reading a post on here about scans, and looking at drum scan sizes, they are between 300mb and 800mb file size.
Out of interest, is there a recommended amount of memory needed, say per 100mb of file size, or anything?
My PC has 4GB of ram - how big an image file can I safely go to before Photoshop and everything else grinds to a halt?!
Up to now the PC has just had digital SLR images at maximum RAW size of around 20MB I think.
I'm at the early stages of thinking of getting an Epson V750, and am wondering whether my PC would be up to it.
Thanks for any advice.

[Peter Mounier]

Photoshop asks for a minimum of 5 times the file size for things like history states, and cache. If you want to keep other apps open and usable, you would do well with more. So for an 800mb file, you should have at least 4gb.

Peter

[Steven Barall]

Also there is the memory required just to run the system properly. If it's Windows, you may need up to one gig or memory, less for a Mac.

Another thing, if your computer is running a 32 bit operating system, even though you may have 4 gig or RAM, the system will only use 3 gig so you need a 64 bit system to be able to use more than 3 gig. Any new computer these days will be 64 bit but you have to make sure. Happy holidays.

[Mike1234]

And it's not just the OS but the MB and chipset as well that affect RAM usage... not to mention slots.

[AFSmithphoto]

In addition to physical memory, you will find a healthy dose of vitual memory can be quite helpful.

Be sure your OS allocates a FIXED amount of virtual memory on startup. Ideally this would be on a fast drive you are using as a dedicated scratch disk. Failing that, try to keep it on a drive that is less that 50% full and well de-fragged.

[Jeremy Moore]

There are some tweaks you can do to your system such as turning down the number of history states (if you're working with non-destructive edits you can turn it lower than if you aren't--safely--imo) and having dedicated scratch space pulled from the outer edges of a hard drive to speed up the computer when working with large files.

I'm sure someone here has some more non-RAM tweaks to help.

One of my favorites for large files is to drop the ppi, do everything in adjustment layers then paste back in the much larger file--or drag the layers on to the large file. I do this when working with panoramic Betterlight scans.

[AFSmithphoto]

Yes. Jeremy made a great suggestion there. Check out this link:

http://www.westcoastimaging.com/wci/...guidefile.html

[newmoon2night]

Also there is the memory required just to run the system properly. If it's Windows, you may need up to one gig or memory, less for a Mac.

Another thing, if your computer is running a 32 bit operating system, even though you may have 4 gig or RAM, the system will only use 3 gig so you need a 64 bit system to be able to use more than 3 gig. Any new computer these days will be 64 bit but you have to make sure. Happy holidays.

Steven - thanks - that explains something I've not understood before - and that's why I have 4GB ram installed, and the operating system only shows 3GB. I hadn't realised that it was actually using just 3GB and the other 1GB is wasted effectively. The operating system is XP Pro SP3 2002 version, and 32 bit.

[adonis_abril]

Also, older version of photoshop does not take advantage of 64 bit processing...CS4 for Windows, I believe is the only one cable of this...Mac version is probably coming. You can also set the percentage of ram photoshop uses under preference > performance > memory usage.

[Richard Kenward]

OK guys here are some ideas for you. Get as much ram as you can cram into your system and then try this. If on a Windows 32 bit system get RamDisk Plus 10 and it will allow you to handle that extra ram as a Photoshop scratch disk. It will also allow you to pop your paging file on it is you have enough ram. Do the same with RamDisk 64 Plus for a 64 bit system. You will be astounded by the increase in speed. As a matter of interest, I'm in the middle of working out the fine details of a new system that will be able to address 128G of ram simply due to our success with a less capable system using the RamDrive technology. Many of our files start life in the region of two Gs as the result of drum scanning or Betterlight scans of paintings, and general artwork copying and speed with large files not only is cost effective, it allows you to try out far more possibilities than would otherwise be possible. Please note that this technique does not require a 64bit version of Photoshop.

I hope this helps someone here.

Cheers

Richard Kenward

www.precision-drum-scanning.co.uk &
www.artisan-digital-services.co.uk