“What does 64-bit computing mean, practically speaking? In a nutshell, it lets an application address very large amounts of memory–specifically, more than 4 gigabytes,” John Nack, Senior Product Manager, Adobe Photoshop, writes on his blog John Nack on Adobe.

Nack writes, “It’s also important to say what 64-bit doesn’t mean. It doesn’t make applications somehow run twice as fast. As Photoshop architect Scott Byer writes, “64-bit applications don’t magically get faster access to memory, or any of the other key things that would help most applications perform better.” In our testing, when an app isn’t using a large data set (one that would otherwise require memory swapping), the speedup due to running in 64-bit mode is around 8-12%.”

Nack writes, “What’s Adobe doing with Photoshop? In the interest of giving customers guidance as early as possible, we have some news to share on this point: in addition to offering 32-bit-native versions for Mac OS X and 32-bit Windows, just as we do today, we plan to ship the next version of Photoshop as 64-bit-native for Windows 64-bit OSes only.”

MacDailyNews Note: Related articles:
Apple does 64-bit right, Microsoft… not so much – August 03, 2007
Apple’s Mac OS X Leopard is 64-bit done right, unlike Microsoft’s Windows Vista kludge – August 14, 2006
Apple’s Mac OS X Tiger operating system is a true 64-bit environment – April 21, 2005

Nack writes, “The development is frankly bittersweet for us: On the one hand we’re delighted to be breaking new ground with Photoshop, and when processing very large files on a suitably equipped machine, Photoshop x64 realizes some big performance gains… On the other hand, we work very hard at maintaining parity across platforms, and it’s a drag that the Mac x64 revision will take longer to deliver. We will get there, but not in CS4. (Our goal is to ship a 64-bit Mac version with Photoshop CS5, but we’ll be better able to assess that goal as we get farther along in the development process.)”

Nack writes, “On the Mac Photoshop (like the rest of the Creative Suite, not to mention applications like Apple’s Final Cut Pro and iTunes) relies on Apple’s Carbon technology. Apple’s OS team was busy enabling a 64-bit version of Carbon, a prerequisite for letting Carbon-based apps run 64-bit-native.”

Nack writes, “At the WWDC show last June, however, Adobe & other developers learned that Apple had decided to stop their Carbon 64 efforts. This means that 64-bit Mac apps need to be written to use Cocoa (as Lightroom is) instead of Carbon. This means that we’ll need to rewrite large parts of Photoshop and its plug-ins (potentially affecting over a million lines of code) to move it from Carbon to Cocoa.”

Nack writes, “Now let me be very clear about something: It’s entirely Apple’s call about what’s best for the Mac OS and how to spend their engineering cycles. Like any development team, they have finite resources & need to spend them judiciously. They’ve decided that Carbon 64 doesn’t belong on their roadmap, and we respect their decision. It’s up to Adobe to adapt to the new plan.”

Nack writes, “As soon as we got the news in June, we began adjusting our product development plans. No one has ever ported an application the size of Photoshop from Carbon to Cocoa (as I mentioned earlier, after 9 years as an Apple product Final Cut Pro remains Carbon-based), so we’re dealing with unknown territory. We began training our engineers to rewrite code in Objective C (instead of C++), and they began prototyping select areas to get a better view of the overall effort.”

“In short, Adobe has been taking prompt, pragmatic steps to enable 64-bit Photoshop as quickly as possible on both Mac and Windows. It’s a great feature, not a magic bullet, and we’re delivering the functionality as quickly as each platform permits,” Nack writes.

More in Nack’s full blog post here.

MacDailyNews Take: Apple CEO Steve Jobs has repeatedly told developers at multiple WWDC events for years now that the future of Mac OS X development is Xcode. Adobe was told to move to Cocoa years ago. They didn’t. Hence the massive delay in getting native Photoshop and other apps for Intel-powered Macs.

For years now, ever since the Adobe prefers PCs over Macs incident, we have believed that Adobe isn’t as attentive to Mac users as they should be. This latest escapade has not helped to change our minds.

Okay, so let’s play along with Nack and pretend for a moment that having/not having Adobe’s Flash on Apple’s mobile WiFi Multi-Touch platform (iPhone/iPod touch) has absolutely nothing at all to do with this and see what we’re left with: Adobe is late on the Mac, their code is old, they had notice to update long ago, but they only made half-hearted attempts to get their code in shape for the future.

Why is Adobe so far behind on the Mac? Because they thought the Mac was dead. But, they were wrong. Dead wrong.

MacDailyNews Note: MacDailyNews has been using Pixelmator (US$59) exclusively in place of Adobe Photoshop since early December 2007 for online graphics. Obviously, we highly recommend Pixelmator. Pixelmator harnesses the full power of Mac OS X. It takes advantage not only of Core Image, Open GL and Automator, it also supports ColorSync, Spotlight and many other Mac OS X technologies. Pixelmator was built exclusively for Mac OS X using Cocoa — and it shows. Pixelmator supports over 100 different file formats and can easily open and save Photoshop files with layers. Plus, it is “demoware,” so you can try it before you buy. Read more in our article: Pixelmator gives Adobe Photoshop Elements a run for its money – March 10, 2008