An Adobe Systems tool that lets older software handle raw images from newer digital cameras is about to leave behind Apple's PowerPC-based Mac era.

The upcoming version 6.4 of Adobe's DNG Converter will be the last to run on the older Macs, said Lightroom product manager Tom Hogarty in a blog post over the weekend. The software is used to convert digital cameras' proprietary raw-format images into Adobe's Digital Negative format. It's useful in part because older versions of Photoshop aren't updated to support newer cameras, but using the DNG Converter can bridge the gap.

"The PowerPC (PPC) Mac systems, commonly referred to as G4 or G5 systems, represent a significantly different platform than the Intel-based solutions Apple started offering in January of 2006. Due to the differences in software development environments, Photoshop CS5 and Lightroom 3 both dropped support for PowerPC systems in 2010," Hogarty said. "However, there is increasing overhead required to support the PowerPC code base in the DNG Converter, so the final DNG Converter 6.4 update will be the last update to support PowerPC systems."

Apple announced its plan to move Macs from PowerPC processors to Intel x86 processors in 2005, a shift that was very disruptive for software but that brought better performance, especially for laptops.

Since then, Apple's iPhone and iPad products--even more sensitive to battery constraints than laptops--have helped establish clout for still another architecture, the ARM-based chip family.

Adobe's phase-out of PowerPC support is no surprise, given how elderly in computing-industry terms PowerPC Macs now are. My first thought on reading it was that perhaps it means Lightroom 4, which uses the same raw-processing engine as the DNG Converter software, will be coming soon.

Adobe updates Lightroom periodically to support new cameras' DNG Converter 6.4 is based on the same engine as Lightroom 3.4, currently in testing. If the DNG Converter 6.4 is the last with PowerPC support, I thought, perhaps that indicates the end of one product cycle.

But perhaps not.

Adobe released Lightroom 1.0 in February 2007, Lightroom 2.0 in July 2008, and Lightroom 3.0 in July 2010.

Even if the gap between 2.0 and 3.0 was unusually long, it seems unlikely that 4.0 would arrive less than a year after 3.0, stronger competition from Apple's Aperture notwithstanding. So perhaps this is just where Adobe decided to draw the line for PowerPC.