Why does this PNG image on twitter look different when clicked?
This morning on twitter there was a tweet with the text "click on this picture". When picture is clicked, it's opened in wider viewer, but looks completely different.
I tried to analyze this picture in ACDSee, and I also tried uploading on Facebook, but it's happening only when embedded on twitter. I don't have much knowledge about graphics so please explain this to me. Why does this PNG image change only when clicked on Twitter?
Screenshots (left = before clicking; right = after clicking):
Here's the original picture.
The picture doesn't change. The background color of the page does.
It's a transparent PNG. The whites are not visible on a white background. The blacks aren't visible on black background.
The normal post is on white. The modal view is on black.
If you change the background color...