Downsampling

I have received an unexpectedly large amount of traffic based around the iPad retina wallpaper post. Unexpected because in the past I have not experienced such a huge rush when posting like minded articles such as those for the original iPad and iPhone 4. It seems in this time demand for device specific wallpapers has exploded and I have seen countless content farming “retina wallpaper” websites and the like pop up all over the place.  I am humbled that so many people have found their way over here and have been enjoying what I have made available.

With this boost comes a few problems though, the wider the scope of readers the more likely it will be that little issues will come up. I shouldn’t say problems, they aren’t problems, lets call it helpful or constructive feedback. Being the open minded person I am I figured I could answer a few questions and concerns and wanted to do it here rather than trying to cram them into Twitter.

Most questions that have come in over the last day or two have had to do with the retina images themselves. One was addressing the slightly off center nature of one of the photos, one was asking about JPG compression, and a few were about problems with the resolution.

The most alarming of these was a problem with the resolution of the images. I have heard varying reports that the images I made available were not at the new iPads full resolution but were actually downloading at 1024×1024. This is a strange issue and is both true and completely untrue at the same time. Oddly enough, Safari puts a limit on the maximum resolution of images it allows to be displayed in an apparent effort to increase the overall speed of web browsing. This limit falls in right at 1024, the resolution of the old iPad screen.

I can’t help but imagine that this is something that will be addressed in the future with a simple update and was somehow overlooked as they moved into the higher resolution screens. This and with ultra high resolution screens such as this, the web suddenly just got a lot more expensive. At any rate, it has been a confusing experience for myself and readers as when you click to download a high resolution wallpaper thats exactly what you expect to see. The trick here is that as soon as you tap and hold to save the image internally it will save at its full, original resolution. This is based on user reports because I do not have a new iPad on hand for testing so if anyone has any further questions, comments, or concerns on the matter please, let me know in the comments below or through email. More information on this issue or at least other places I have read about the problem are here, here, and also via podcast here on 5by5.

Now, for the other questions. There was an image, Going Home, that I missed the cropping a bit and was off center. I have re-cropped the image and simple replaced the file so if anyone else noticed this, please, delete the old version and update to the newer image.

The last thing that came up was someone who was adjusting an image a bit in photoshop and/or iPhoto and said the result was increased compression artifacts showing in the image. This is not some kind of sneaky way of keeping people from messing with my images (though thats a clever idea!) it is simply a symptom of me using the desktop versions of images as my source material rather than the originals. I do regret not having them with me here while I am traveling. I will be away from home until April 23rd and until then I am most likely unable to access those files. While I always save my wallpapers at the highest possible jpg compression rates there is still room for them to loose a bit of information in the process so while they look OK for their intended purpose, further editing may result with increased attention to the limitations of the JPG format.

Thats all for now, just a quick update to answer a few frequently asked questions on the new images. See you guys again soon!

Update: Further speculation (read here, and here) has lead me to believe that mobile safari may have an issue with JPG’s that are not progressive scan versions. I will go back through and save them again with this method and see if it clears up the bug. So frustrating. I am really hoping that this will not result in more artifacts in the images. I can’t spare another afternoon cropping images for quite some time. This would also indicate that even when saving images to the library they very well may also be the small size from what I am hearing…

Straight from apples Safari developer recourses there appears to be limits due to the amount or RAM in the devices. “The maximum decoded image size for JPEG is 32 megapixels using subsampling. JPEG images can be up to 32 megapixels due to subsampling, which allows JPEG images to decode to a size that has one sixteenth the number of pixels. JPEG images larger than 2 megapixels are subsampled—that is, decoded to a reduced size. JPEG subsampling allows the user to view images from the latest digital cameras.” Interesting indeed.

If anyone is having this issue, could you let me know in the comments if you are using Wi-Fi or if you are on a 3g/4g network. Just part of my troubleshooting.

Update two: To recap whats been going on, the issue has proved maddening and I have heard different reports from different readers about success or failure in downloading certain images versus others yet all were saves in exactly the same manner. Not to mention some reporting success in using the save to disk trick while others have no luck at all. Even more discussion on the issue of image size limitations on iOS here and according to this discussion it may be a bug within ios5, well, a “feature” that backfired and caused these issues.. It is still a bit maddening to deal with and most workarounds have failed so far for me so I am taking a break from it until someone can possible offer more information on what may be a god solution. At the moment I have read from readers that they have been successful in using their mac to download the full images and then emailing them to their iPads in order to get the larger size to save to the device. Meanwhile, I will continue to poke around and read whatever information comes my way about the subject. If anything changes I will let everyone know and make alterations to the files accordingly. Thanks for your patience.