Apple is a company world-renowned for its attention to detail, but the company may have left some important data on its Macs that reveal a little more about its creative process. Reddit user CrazyKiwiCake spotted on Friday that one of the wallpapers included with the Mac’s operating system still has its EXIF data attached, normally used by cameras to identify the equipment used to take the picture.

The photo, depicting a starlit night in Yosemite National Park, seems to have been taken by a Canon 5D mark III, a high-end DSLR used by photography professionals. The lens is a 17-40mm f/4 L series, with the picture taken at 17mm with a wide f/4 aperture. The shutter speed was set to a slow 30 seconds, presumably to capture as much light as possible in the darkness.

It appears to be the only wallpaper in OS X El Capitan, the latest operating system, with its EXIF data intact.

The image (above) comes with all installations of OS X El Capitan.

That’s not all. Redditor hrrrrsn spotted comments hidden in the EXIF data.

Please darken some of the stars that are a bit smaller and darker, so there is a little more difference in the starfield., Please remove some of the noise in the sky, Please darken the sky a bit overall, but more so in this brighter area that is circled., Can we refine this area so it doesn’t look like it was duped from the spot to the left?, Please fill in this area close to the edge with more tree so it doesn’t create awkward negative shapes., As the stars transition towards the horizon, they should become much less dense. You can see in the original, there are fewer stars towards the bottom., Less pink in this section of the sky. Please reference the original which is more blue. Overall, stars can be a touch sharper., The brightness of the stars should be brightest at the top, and slowing fading out towards the bottom. We can stand to brighten the largest stars at the top here.

It’s hard to prove definitively, but it reads like design feedback given to whoever was working on the image in post-production. Apple ships 51 wallpapers in OS X, and these comments suggest great care is taken to ensure each one is polished to perfection.

Apple is planning to launch the follow-up to El Capitan, macOS Sierra, this September. The release will bring Siri to the Mac, improve window management with a new tab system, and make it easier to pay for items online.

Continuing with the tradition of making releases after places in California, macOS Sierra is named after the Sierra Nevada mountain range. Current beta versions feature a sunset over the range as a default wallpaper, and if these EXIF comments are anything to go by, Apple spent a long time making sure the image was spot on for when Sierra launches.

Photos via Apple, Getty Images