Okay everyone, I've got a really weird question that I'm hoping someone can shed light on.
So I have a bunch of images on my computer that have watermarks on them. They're all JPEG. I was just using Finder on my Mac to try to locate a specific image. In the Finder options, I have the preview mode on, so that when I look at a folder, it shows thumbnails of all the images.
Here's where it gets weird.
As I was scrolling through the Finder window, looking for a particular image, I dragged the zoom slider out so that I could make the thumbnails smaller, so I could get through them faster. When I did that, I noticed that on a lot of the photos, the watermarks just.... disappeared. I zoomed back in, making the thumbnails larger, and the watermarks in the thumbnails came back. Zoom out again, and they disappeared again.
How is this possible?
When I open the photos in Preview, the watermarks are all still there---and when I zoom out in Preview, they never disappear. So this is only happening in the Finder window. I opened some of these photos in Photoshop to see if somehow there was some hidden layer---nothing. These are all flattened JPEG images, Photoshop only reads them as having a single layer. And yet when I zoom out on them in Finder, the watermark vanishes. And it's not just my eyes playing tricks; when the watermarks disappear, I can see new content in the photos. For example, one of the photos is of a chair, and the watermark covers its legs. When the watermark disappears, though, I can suddenly see the carving of the wood in the leg---which is totally blocked behind the watermark when I zoom out.
Does anyone know how this is possible?
I don't know a lot about imagery, but it seems like the images are somehow "adding" a watermark at a certain size. Which means that somewhere in there, there must be an image without the watermark that I should be able to get to somehow, right?
Thanks for any light anyone can shed on this!