There's a mini debate raging right now on what the best crop preset would be for Cake. Though we can all agree that being able to crop in Cake would be ideal (or have some fancy machine learning features enabled), that's further down the roadmap. In the short term, the strategy is to come up with a "one size fits all".
Currently, images are center-cropped and I feel like I have to make a strong stance against that direction.
TLDR: Let's go for a Top Third.
First, I believe that more images follow the rule of thirds rather than a center composition. It's rare that an image will contain an equal distribution of interesting content on both the top 1/2 and bottom 1/2 split in the middle.
Given that the top thirds or bottom thirds will contain more of the valuable/interesting information, a user will most probably be left with a feeling of unsatisfaction... but not quite enough unsatisfaction to re-upload a new image.
Not only will the user not get the full satisfaction of the perfect thumbnail, the Cake home page will also look uglier for everyone involved.
Now, if the crops prioritized a top or bottom third - the thumbnail would either work perfectly, or be completely off. A user would now have a clear choice of correcting the thumbnail to accurately represent their needs... or leave it as is. And while we might not want people to leave feeling 100% unhappy with a crop - the next best thing is giving people the opportunity to correct it.
So why top thirds?
Crops that are the most annoying are generally the ones that cut off a person in half, and since humans walk and sit vertically, there seems to be a lesser chance of cutting them off in an unflattering way.
Obviously this works less well on animals or anything that is longer rather than wider but... we gotta start somewhere.
Here's a side by side comparaison of the last three posts on Cake.
- Left (top thirds) is clearly IMHO the superior "average" crop.
- Middle is "just off" on all counts.
- Right (bottom thirds) is clearly wrong (but that's just coincidence) and user would know that they chose the wrong image for thumbnail.