Sizing images to display correctly on iPad mini 2

A while ago a talented Verizon salesman sold me an iPad mini 2 that I didn't really want or need. Now that I have it, I thought I might as well load some photos to show off on its pretty screen. I decided to make jpegs specifically optimized for that purpose.

I sync my photos to the iPad using iTunes on a PC.

Because the screen is reasonably wide even in its shortest dimension, I decided to make all my jpegs based on the assumption that the viewer would keep the iPad in its vertical (portrait) position all the time rather than turning it back and forth depending on the aspect ratio of the picture.

The iPad mini 2 screen is 1536 x 2048 pixels, with 326 pixels per inch resolution. This meant that I would make all landscape format photos 1536 pixels wide, letting the height fall where it may. I would make portrait format photos 2048 pixels high unless the width came out to more than 1536, in which case I would make them 1536 pixels wide.

This worked out fine until I discovered an iPad software bug (feature?), which is this: If a picture is pretty close to the same aspect ratio as the screen, the software zooms in to completely fill the frame, cropping off some of the picture, either from the sides or the top and bottom. (How close is "pretty close"? See below.)

This was not acceptable. I crop my pictures exactly as I want them to appear and don't want some piece of software second guessing me. If one double-taps the screen to zoom in on the picture, then double-taps again to zoom back out, the picture is displayed correctly: full-sized, with black bars filling out the unused edges of the screen. But the viewer would have to do this every time for every picture having this issue, which would be a pain in the neck and also not acceptable to me.

I am obviously not the first person to discover this bug/feature. Googling brings up various discussions but no cure that I could find.

The solution for me was to add my own black bars to the edges (left and right or top and bottom) to fill out the whole 1536 x 2048 frame when necessary. And when is it necessary?

By trial and error, I discovered that a picture that's a full 2048 pixels high and 1396 pixels or fewer wide will display correctly. But make it even one pixel wider than 1396, and the software zooms in, cropping the top and bottom of the image.

Going the other way, an image that is 1536 pixels wide and up to 1860 pixels high displays correctly. Any image taller than 1860 gets cropped from the left and right.

So the bottom line for me was this:

Of course, one could just pad every image out to the full 1536 x 2048, but that would bloat some files unnecessarily. And anyway it was more fun to figure this out.

Does it crop, or automatically reduce the image to fit the screen? I have not found it necessary to fit the screen exactly. I expect to get "cropping" on the long side because the aspect ration of the iPad doesn't match that of the camera (2:3). Unless you lock rotation, the iPad will rotate and fit the image to the screen to fit either orientation. Obviously a vertical image will be a lot smaller with wider margins on an horizontal iPad. If the image is smaller (in pixels) than the screen, the iPad will not resample nor expand the image to fit unless you zoom manually.

I normally size "portable" images to 2400x3000 pixels (8x12"), which takes a lot less memory than the original, and is good enough for distribution to clients for publication. They display correctly on my iPad 2 Air. Another possibility is to install and use Lightroom Mobile. Among other things, LRM will synchronize with images stored in a collection on your desktop. You can view them via iCloud or download them to your iPad.

If you want to size images to fit the "box" presented by the iPad, you can do so easily when exporting from Lightroom (or manually from Photoshop). Only the pixels count, not the nominal dimensions. You only need to do this to reduce the load on memory or update time between screens.

Just in case anyone ever looks at this thread again, a couple of final points:

• My information relates to the automatic (and unwanted by me) zooming performed by the Photos app on some images without any double-tapping or stretching.
  
• I did the tests on an iPad mini 2 with iOS 10.3.2. Other devices or future software updates might behave differently.
  

Photoshop can do batch resizing to fit a specific height x width pixel frame. I.e. it looks at the maximum pixel dimension and reduces it to fit the height or width of the target frame.

I've used this to resize 3:2 images to fit 1080-HD & 4K TV displays (without distortion). It rips through images at a rate of several per second, and will save them in a specified target directory.

Don't ask me for detailed instructions. It was a while ago, and I've been to sleep since!

Photoshop can do batch resizing to fit a specific height x width pixel frame. I.e. it looks at the maximum pixel dimension and reduces it to fit the height or width of the target frame.

 

I've used this to resize 3:2 images to fit 1080-HD & 4K TV displays (without distortion). It rips through images at a rate of several per second, and will save them in a specified target directory.

 

Don't ask me for detailed instructions. It was a while ago, and I've been to sleep since!

Make an action (I have a set called ARs and a resize action seen below). Image Size> Resize, configure resize via pixels. Then use Automate> Batch to load that action set and actual action and access a folder of images to process.

http://digitaldog.net/files/Batch.jpg