The Facebook Open Graph image is the image linked to a web page and displayed by Facebook in the news feed when the said page is shared:
This image has special requirements, in particular its dimensions. We already saw that many web sites did it wrong. What about the biggest web sites, the ones everyone know? This article focuses on the Alexa's 500 worldwide top sites.
65% of the top sites have no Open Graph image. As simple as this. You could expect such sites to be at the bottom of the list, but actually even the first ones lack of it:
What about the remaining 35%? Well, 8% don't match Facebook ratio requirements. For example, Vimeo is using an image which is roughly 5:3.
Facebook expects 19.1:10, so it crops 13% of it to make it fit its news feed:
Some other sites have the ratio right, but the images are too big. This is not documented anywhere, but when Facebook gets a small square picture, it displays it as is in the news feed. But when the image is big, Facebook processes it as a wide image. 7% of the top sites fall in this trap. Among them, YouTube (the 2nd most visited web site in the world) and Amazon:
That leaves us with only 20% of sites that:
Suffice it to say that this result is rather poor.
In one hand, one could think that YouTube homepage sharing is not that important. After all, what is heavily shared across Facebook are YouTube videos (and this part is done right). In the other hand, we need to consider that someone at YouTube created an image for the second most visited website in the world, and this image is not that great. And 80% of the top sites are more or less in this situation.
Thank's to Meta Chart for the neat online tool!