Q: I have photos that are perfect that I’ve stored on my computer, an external drive and flash drives. But when I view the photos, they have bands of gray, green, or brown covering at least half of the picture.

What causes this? Is there a way to restore the photos to their original appearance? I’m sending a sample photo with this e-mail.

Linda Gonzalez, Metairie, La.


A: Unfortunately, the data file of your sample photo is corrupted and can’t be fixed.

However, it’s easy to see why you thought the photo was perfect. When I viewed a tiny “thumbnail” version of the photo in Windows Explorer, the entire picture was visible. But when I opened the photo in a ­viewing program, half of the picture was missing.

Why? The thumbnail image you see in Windows Explorer is typically a separate picture from the actual photo. Both are created when you take a picture with your camera, but if the photo is subsequently edited or corrupted, the thumbnail often isn’t updated to reflect the changes. It still looks like the original photo.

In your case, I suspect the actual photo was corrupted by a flawed camera memory card, so I recommend buying a new card. If the problem occurs again with the new memory card, other potential causes are a flaw in a memory card reader or a malfunction in the camera’s ­electronics.

But don’t immediately throw away the old memory card. Depending on how the photo file was corrupted, it may be possible to recover a previous, undamaged version of the photo that’s hidden on the card. However, this won’t work if the photo’s storage space on the card has been overwritten by more recently taken photos. You can find out by running a file recovery program that works with flash memory devices, such as the free version of Recuva available at tinyurl.com/olbsadf.


Q: Where can I find a comprehensive comparison of the Apple vs. Google Android devices? What are the most important factors?

Jerry Hartlaub, New Brighton


A: There’s no obvious correct choice between smartphones and tablet computers that use Apple’s iOS operating system and those that use Google’s Android. Most consumers buy based on personal preference or price.

You can find online reviews that take one side or the other, but some are so extreme that they remind me of the partisan Microsoft Windows PC vs. Apple Macintosh debate that raged for years. For a more evenhanded analysis, see tinyurl.com/nnugu2u for smartphones and tinyurl.com/4r56bof for tablet ­computers.

Here’s a sample: The smartphone reviewers say that Apple has the ­better camera in most cases, but that Android has the better “voice assistant” for dictation. The tablet reviewers say that Apple has more apps available, while Android is available on a wider array of devices.


E-mail tech questions to steve.j.alexander@gmail.com or write to Tech Q&A, 425 ­Portland Av. S., ­Minneapolis, MN 55488. Include name, city and telephone number.