Hi!
I've been perceiving these 3D images since about six months ago. I didn't notice them until one day when I watched the lyric video for the song "Ruby Tuesday" by The Rolling Stones where they used a lot of contrasts in the video like blue, purple, red and yellow. I perceive most of the video in 3D and it's very cool cause it's a whole other experience. When I asked my friends and family if they saw it in 3D too they said they didn't, so until this day I was the only person I knew with this hability. Also, the 3D effect in that image you've shown is very strong for me too.
Here's the link for the video if you're interest in seeing if it works with you.
Btw, I can only perceive this 3D effect in images with contrasting colours or with certain patterns.
Here's a screenshot of the part that gives me the most 3D effect from the video:
