Now that I have that wallpaper pack out of the way I can get back to other things here on the site. Many were curious to hear more about how I settled on the resolutions I chose to use to take advantage of the “parallax” effect in Apples iOS 7.
The short answer is more or less a lot of trial and error. Before iOS 7’s official release I remember seeing a twitter message (here, then here) posted by illustrator David Lanham who had done his own testing and come up with a general rule of thumb that a 200px padding on all sides of an image would be enough to over the effect.
Given the chance to finally test it on an iPhone 5 I quickly noticed the shortcomings of this approach which was made more or less as an educated guess in the early days of iOS 7 being in developers hands. No fault to David really on this, it did make perfect sense at the time. Problem was the OS seemed to be cropping too much of the image and did not let me set a vertical adjustment when deciding how the image should sit on the screen. The 200px padding approach seems to make sense on the surface but it eats up far too much of the image in practice because of the way Apple handles the process. When cropping a wallpaper for a device I want to have as much control over the end result as possible.
As far as I know his mention of this theory was the first time it was brought up and since then has been widely adopted as being the best image size for the effect. Un-satisfied after my own testing, I took to the net in search of other opinions and came across someone that had ripped the original apple images out of the iPhone version of iOS 7. While the resolutions seemed completely arbitrarily size wise, as soon as I tested it I quickly realized it was in fact the ideal resolution.
I tested this by cropping images to Apples default wallpaper resolution then drawing a red box on top the pixel size of the iPhones screen resolution. I then loaded the resulting image into my iPhone and checked to see where the edges of the red box fell on screen. After trying a number of different cropped resolutions I discovered if I made any changes to the resolution set by apple the box would no longer line up ideally on the screen at a neutral position.
When it came to the iPad the same issues arose and while no one was out there talking about ideal iPad resolutions for parallax I was able to find someone sharing Apple’s included images online and sure enough the resolutions matched up better than any others I had tested.
All in all it seemed obvious to me that whoever at Apple was working on the effect found the ideal amount of give to the parallax panning to get a natural feel and set the dimensions of new desktop images to fit this ideal down to the pixel. Therefore, to get the most natural fit for your wallpaper images in accordance to their current programming I highly recommend you crop iPhone wallpapers to 744x1392px and iPad wallpapers to 2524x2524px.
My only question at this point is weather or not apple will end up tweaking that ratio in the future. I would imagine testing was thorough enough so that these resolutions will be just fine for a good long while.
So for all those “maybe 200px padding is best” tinkerers out there, think again. I can safely say that apples own set resolution is the clear winner for accuracy in their new iOS design.
If you are in the need of some nice wallpapers cropped, zipped and ready to roll then by all means take a look at my latest pack of wallpapers for iOS devices here.