How to change number on picture

Picture changes color in WhatsApp

Okay, maybe you've heard about it, maybe not:
WhatsApp is haunted by an image that changes color when you interact with it.
- When you get it, it's red.
- Once downloaded, it's pink.
- If you tap the picture to look at it completely, it is burgundy.
- If you forward it, it's green.

Well, well, we don't believe in fairy tales and magic, so download the picture on the PC, and lo and behold, it's a semi-transparent .png with .jpeg ending that plays around with the different background colors in WhatsApp. So much for that.

But now to my real question: How does it work?
I tried to recreate it with my own picture with the same semi-transparent color - the effect does not occur.
I tried to send the downloaded image again (WhatsApp web and on the mobile phone) - the effect does not occur.

The effect apparently only actually occurs if you forward the original ... Hence my question, what am I doing wrong, or do you have any ideas how to reproduce this glitch / exploit?
I like to attach the corresponding picture, but as I said, the effect can apparently only be determined with the forwarded picture ...

Attachments

  • WhatsApp Image 2018-10-23 at 10.32.13.png