Icon in field depending on another field value

HI all, newbie question here, and something i cannot figure out.
I want to create a new field, but have it show a icon. But the icon will be different depending on another field for that entry. for example;

Field1                        Field2              
red                            shows image from example url1 https://images.url.com/red.png
blue                            shows image from example url2 https://images.url.com/blue.png
green                          shows image from example url3 https://images.url.com/green.png

So when looking at the first line, the field2 will show a red icon, as the field1 text matches 'red'

hope that makes sense, thanks.