Scott Byer of Adobe sparked off a flourish of excitement over the holidays, with photoshopers wishing for a little extra in their xmas stockings, when he wrote about the potential for CS3 to become a 64bit application in his blog.
Today Russell Williams, another Abobe staff member, has added further clarification with this reply…
The biggest point about making Photoshop into a 64 bit app is: “why?”. What would we gain? The ability to process bigger images? No. Some new whizzy feature? No. There is one basic reason that users would care about: performance.
What kind of performance? Two have been touted: faster operation because of the use of more registers in 64-bit mode and the ability to work on 64 bits of data at a time instead of 32. As far as we’ve been able to measure the gain here is minimal — zero in most cases.
The other way that 64 bit operation could improve performance is by changing the way we make use of >4GB RAM to process very large files. Note that’s “could improve” not “would enable”, because CS2 and CS3 can already use >4GB RAM and can already process very large files. The main user-visible benefit of a 64-bit photoshop is an as-yet unquantified improvement in performance with very large files on very large RAM systems.
There would be some rare cases in which 64 bit would allow certain operations that run out of memory when applied to huge images to work — filters that require the entire image to be all in one place in RAM before they can work, (I think Polar->Rectangular is one of these) currently can’t work on huge images.
The pull for Adobe is threefold, and we don’t yet know the relative importance of these:
1. We’re always looking for performance improvements.
2. Going to 64 bits greatly simplifies the way we manage our memory (as long as we don’t have to maintain a 32-bit version as well).
3. It will look good on the box. That is, customers unaware of the limited actual benefits of 64 bit may exert lots of pressure for us to do it. Sales could slump because “I’m waiting for the 64-bit version because it’ll be *way* better — thinksecret says it’ll run twice as fast and cook me breakfast!”.
~ Russell Williams