On 2012-01-14 14:09, Karl Shah-Jenner wrote:
"The main disadvantage of 64-bit architectures is that relative to 32-bit architectures the same data occupies more space in memory (due to swollen pointers and possibly other types and alignment padding). This increases the memory requirements of a given process and can have implications for efficient processor cache utilization. Maintaining a partial 32-bit model is one way to handle this and is in general reasonably effective. In fact, the highly performance-oriented z/OS operating system takes this approach currently, requiring program code to reside in any number of 32-bit address spaces while data objects can (optionally) reside in 64-bit regions." http://en.wikipedia.org/wiki/64-bit
That's talking about data *structures* largely. Photo data is relatively unusual in that lots of it comes in just plain big chunks. The structures that keep track of it are a very small part of the total. It is, in fact, the poster child for "application suited to 64-bit architectures".
What a system *can* do and what it needs to do a task is sometimes quite different. Opening a 14Mb image I see it occupies 15Mb of RAM (it's a TIF).. so 66 open images would use roughly a gig of ram - that's having them open and loaded in RAM and not just having them cataloguing or being referenced, but actually open..
When I open a 12MB raw file, it takes 69.8MB in Photoshop. To do any operation efficiently, Photoshop needs at least three times that much data space. To allow for some history rollback, even more is helpful.
Stitch a dozen of those together and it starts to add up to real bytes. I did once stitch a 2GB panorama on a laptop with 2GB. I left it running overnight in the hotel room, and it actually succeeded. I was impressed. My current laptop has 8GB :-).
-- David Dyer-Bennet, dd-b@xxxxxxxx; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info
