This implements a sort of visual hash function.
E.g, the icons above were generated using iconsFromString 120 3.0 5 "Elm".
The idea is to create a unique icon for every possible input.
This can for instance be used as an avatar for anonymous users in a forum.
It might also be used to quickly confirm if two files are different.
From a visual hash function, we want a few different features:
- Every possible value should be easy to remember
- No two values should be too easy to confuse
- Every icon should look 'good' or at least not ugly
- There should be a high number of possible icons, such that collisions are rare
- These properties should also hold for colorblind people
These goals are conflicting, but I think this library (and the idea in general) provides a nice trade-off.
Compared to other well known hash functions like SHA-256 (256 bit) or MD5 (128 bits), this visual hash function has a much much worse collision resistance. The hash icon provides roughly 20 bits of entropy, so it shouldn't be used for anything critical.
The trade-off between collision resistance and good looking icons is adjustable with a cut-off ratio. Color combinations with a contrast ratio below the cut-off ratio are discarded.
To increase the collision resistance, you might want to use multiple icons in a row.
E.g. with a ratio of 3.4 a row of 7 icons provides as many bytes as MD5.
Or with a ratio of 8.4 we would need 8 icons, but it would look much nicer.
Warning: The above is not correct!
The way I generate multiple icons from one string does not provide the expected collision resistance.
Turns out it's much more complicated, read this paper.
TODO: switch to a better hash function such that the above becomes true.
(At least for a reasonably small (1-20) number of icons).
Want to use another set of colors? Another set of icons?
Create a fork!
I didn't make these things adjustable, because I thought most people don't want to make any adjustments.
Also, having a few forks around that take the same idea but with different trade-offs sounds exciting to me.
If you do end up forking this library, please let me know so that I can provide a link here.
Some icons are chopped off. The problem has already been noted here and is hopefully fixed soon.
Note: I will bump the major version every time there are some visual changes. Even if it would technically not be a major change, it would break the implicit contract that the same string always hashes to the same icon.
- 2.0.0 -> Removed brands by default, but they can be enabled if desired.
- 1.0.0 -> First version
- Probably the original "identicon"
- Github's version, e.g. as implemented here
Icons from Font Awesome