How do you stop the iPhone from automatically compressing images?

Question

My designer friend is convinced that the iPhone is compressing his wallpaper images. I Googled it, and no luck. Is this a thing?

Answer 1

It depends on how the wallpaper images are being transferred to the device, and their filetypes. If these are just loose images being copied to the device (or saved to the device via Safari or such), there's no compression that wasn't already there. If the images are being included in an app and are in PNG format, they will be recompressed, though it shouldn't change the quality. JPGs and GIFs are never recompressed. More on the PNG recompression below.

Note that there are some peculiarities in how images show up on an iPhone display related to how LCDs display graphics. If I recall correctly, certain images will look fine in portrait mode but terrible in landscape, or vice versa. There is a fix, but you'll need to Google it, since my casual check didn't find anything.

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*PNG images that are included as part of an app are recompressed by Xcode when the Build and Archive command is run with a device selected as the active SDK in preparation for uploading to the App Store. The recompression is lossless, meaning the image doesn't lose any quality, but it performs some byte-order swapping designed to make it much faster to display the png. The resulting file, if removed from the app bundle, is technically no longer a png and can't be opened.

Sometimes, though it's very rare, this recompressing can corrupt the png file. This SO post describes how to stop a particular file from being recompressed, though you don't want to if you don't absolutely have to.

Answer 2

I believe the answer to your question is no.

Answer 3

Unlikely, unless the Size (in pixels) is Incorrect. First make sure if the image is intact or not. Take a screenshot for your designer friend (holding home + sleep button simultaneously) and let him compare (e.g. In photoshop).