What does initImageAppleJPEG: falling back to libJPEG warning messages mean?

Question

After upgrading my iPhone 5s to iOS8, and using Xcode 6 GM and Xcode 6.0.1, I started to see this message on console:

initImageAppleJPEG:1325: falling back to libJPEG

Anyone else seeing this? I couldn't find an answer online. And I don't see crashes or anything. It might be just an impression, but I've noticed a few hiccups/slow downs when fast scrolling a list of images. Hard to say if it was there before, and I'm just noticing now because of these suspicious messages.

It might also be one of those warning messages that Apple forgets to hide each major Xcode release.

Answer 1

I've found this happens on perfectly valid JPEG images, so I presume that Apple didn't bother to implement all JPEG features in their own decoder, and has to use the de-facto standard libjpeg in some cases.