Image Index
A system based on likes received on images, that incentivizes the most active and liked members of the community.
Born as a way to prevent spam on AstroBin, over the years the Image Index has evolved into a sought-after indication of one's abilities in astrophotography and activity level on within the AstroBin community.
The Image Index is a value calculated using the number of images uploaded and the likes that they received. It's built to be non-inflationary, meaning that you're not guaranteed to improve your index with every upload and with every like.
AstroBin is an open-source project, and the algorithm used to calculate the index can be seen here.
FAQ
How is the Image Index calculated?
The Image index is a function of the number of Likes and the number of images posted by a user,
In general, the more images, you have, and the more likes, the more it will increase.
It was introduced as a system to prevent fake accounts from clicking Like on one's own images.
My Image Index decreased? Why?!? 😡
This is perfectly normal and can happen for a variety of reasons. For instance, your new upload received fewer likes than necessary to increase your index, but enough to make the cut and be considered for index computations.
A common scenario would be the following.
Let's say you have 100 average likes, and you upload a new image. It only receives a couple of likes during the first few hours, and this will lower your average number of likes. This fact will lower the threshold that lets images be considered in the calculation, and therefore you get an initial bump in your Index.
After a day or two, your image achieves 100 likes, in line with your previous average, and this makes the average number of likes go back to 100, excluding from the Index calculation those images that had temporarily been considered. So your Index goes back to a value only slightly higher than your value before uploading this last image.
The important thing to consider is that the AstroBin is not inflationary and it doesn't necessarily grow with every image and every like.
My Image Index is stuck at the same number even tho I received some likes? Why?!? 😡
The Image Index you see on the website is rounded to two decimal points. There could've been a smaller variation that you can't see. Additionally, the Image Index algorithm is not designed to be inflationary: more likes do not necessarily mean a higher Index.
You could get likes on an image, but those likes could lower your Index if they are just enough to be considered by the algorithm but still lower than your average.
Some other astrophotographer has fewer images and fewer likes than me, yet their AstroBin Index is higher. Why?!? 😡
Consistency is key: 10 images with 10 likes each will yield a higher AstroBin Index than 10 images such as one has 100 likes, and nine have none. So the way the likes are distributed across the images matters.
My Image Index is less than 1.00 and I cannot click Like on images. What does this mean?
To prevent people from creating fake accounts to like their own images, low indexes are not allowed certain actions, such as liking or posting without moderation.
To increase your Image Index, you need to get a few likes of your own, it only takes a handful.