But Nack took pains to say that moving to 64 bits, while useful, isn't like flipping a switch that doubles performance.
Modest performance improvements
Based on Adobe's preliminary testing, the 64-bit version of Photoshop CS4 will give a performance kick of about 8 percent to 12 percent compared with the 32-bit version, Nack said. For one particular task--opening up a huge 3.2-gigapixel file on a system with a lot of memory--the 64-bit version is 10 times faster because it doesn't have to write the data that won't fit in memory onto a relatively slow hard drive.
In practice, a huge swath of Photoshop users won't be affected by the difference, at least initially. The transition from 32-bit to 64-bit computing has been creeping sluggishly across the personal-computing industry for years already, and it's going to be some more years before the transition is complete.
Advanced Micro Devices unveiled the first 64-bit x86 chip in 2003. Although AMD and Intel have moved their x86 processors to 64-bit designs, the new Mac OS X 10.5, Leopard, is Apple's first full-fledged 64-bit operating system, and Microsoft's 64-bit versions of Windows are almost unheard of in real-world use.
But it's not unreasonable to assume CS4 will have to hold down the fort until 2010 or so, when a PC with 8GB of memory will be ordinary, and by then, the difference between Photoshop on the Mac and Windows likely will be more glaring--especially for those
users who already had a 64-bit Photoshop CS3 on their wish lists.
Fortunately for Mac users, Intel-based machines can run Windows either with a dual-boot configuration or through virtualization software, so perhaps that could tide them over if Adobe obliges with permissive licensing.
Open the 64-bit floodgates?
Today, most folks with PCs don't bump too hard against 4GB memory limits--indeed, it's not easy to find mainstream computing hardware with memory slots for more than 4GB even when there's a 64-bit chip and operating system. But Photoshop can be a taxing application.
Images are getting bigger and bigger, and Photoshop often is used to composite many together on multiple layers or stitch them together into large panoramas. At the same time, people are starting to store more detail in each pixel, moving from 24 bits of color information to 48 bits and, in the case of the
high dynamic range photography (HDR), often even more. Having more memory also improves Photoshop's ability to track the history of changes to a file.
.
