I have a few avatar pictures that I use for web sites I join. We had some new family pictures taken for Christmas, and I cropped and resized some of them to make new avatar pictures. But whenever I used them, Windows Explorer continued to show the entire image as the thumbnail. Windows caches thumbnail images for performance reasons, so it doesn’t have to regenerate them every time you visit a folder of pictures. I assumed the cache was out of date.
One deceptively simple solution was to open Windows Explorer to the folder containing the images and change the view. You can do this by right-clicking inside the folder and selecting View, then Large or Medium icons (whichever one isn’t already selected). This worked, but when I switched back to the previous view, the outdated thumbnail remained.
So I took a more severe approach. According to this Microsoft Answers post, the thumbnail cache is stored in %LocalAppData%\Microsoft\Windows\Explorer. To clear it out, I deleted all of the thumbcache_*.db files.
But this didn’t solve the problem either. When the thumbnail cache was regenerated, it still had the older image! If I had kept reading the thread I linked to above, I would have realized this sooner. JPEG files can store a thumbnail in the EXIF data. And the thumbnail wasn’t updated after I cropped and resized the image. I confirmed this using MiTeC’s Photo View application.
Don’t forget about this embedded thumbnail if you ever post a cropped photo that has anything sensitive or private. In 2003, Cat Schwartz made this mistake, posting a headshot of herself that happened to be cropped from a photo of her sans clothes.
But back to the problem at hand. The final solution was to use Stripper (great name) to remove the EXIF data. Just so you’re aware, when you drag an image onto the Stripper window, it will overwrite the original image with the stripped version without any confirmation. If you want to keep the original, make a copy first.
And the way to stop this from happening in the future is to use an image editor that updates or removes the EXIF thumbnail when you crop the image. I emailed FastStone Image Viewer support to see if there’s a way to do this that I’m not seeing, and if not, to fix it.