Troubleshooting Tip for image files that will not open

So your "not exactly tech-savvy" friend/sibling/parent sends you a JPEG file with a plea for help. No matter what they do, they cannot get the file to open and display properly. You scan the file to make sure its not some kind of malware in sheep's clothing, and when it scans as clean you find you are unable to open the file as well.

(I've encountered this problem twice in the last month now, so I figured I'd give it a quick write up in case anyone else was getting asked to assist with similar problems.)

It's a weird thing, but it's technically possible to save images with incorrect file extensions in some software. In other words, I might be saving a Windows Bitmap file with a filename of example.jpg. (For the record, Seashore on OS X refuses to let me do this-- as it should.)

If you suspect that might be causing the problem, there's an easy way to find out. Using Notepad (or any similar text editor tool), open the file and examine the first few lines. The majority of graphics files out there will have a "header" that contains information about the image file itself. PNG files, for example, will tend to have "PNG" in the first few characters of the first line-- it's sort of like a species identifier, if you will. Windows Bitmaps will start with BMP in the first line, near the very beginning of the file.

Once you know what the file is actually supposed to be, you can alter the file extension to match the type of image file. From there, the file ought to open properly in your image software.

I know, this is probably old hat for the Photoshop/GIMP veterans-- but like I said, I've run into this problem at work twice in the last month, so there are obviously some folks out there who don't see anything peculiar about overriding the default/suggested extension for the image file with their own idea of what that extension ought to be.

Hope that helps!

A Math/Flickr word problem

I have 145 MBs of photos I want to upload in Flickr. I've already used 5% of my monthly bandwidth. My Flickr client software automatically resizes my photos before uploading, decreasing the overall size from 145 MBs to 22 MBs. After successfully uploading the resized photos, I get a notice that I've used 27% of my monthly bandwidth.

Q1: How many MBs does Flickr allow me to upload per month?

Q2: If my client hadn't automatically resized the photos before uploading, how much of my bandwidth would I have used?