README
¶
identicon
go package to generate github identicons
based on dgraham's rust identicon
https://github.com/dgraham/identicon
algorithm
github identicons are generated from the md5 hash of a user's id.
there are two components to an identicon: the pattern and the color
for example: my user id is 32273214
$ echo -n "32273214" | md5sum
3a44233aabcac24ed7c6e160b30f4289 -
pattern
the first 15 nibbles of the md5 hash make the identicon pattern (nibble == half byte == 4 bits)
even nibbles result in colored (foreground, o) pixels, odd nibbles result in gray (background, -) pixels
in my case:
3 a 4 4 2
3 3 a a b
c a c 2 4
produces:
- o o o o
- - o o -
o o o o o
the final identicon pattern is made by rotation and mirroring:
o - - - o
o - o - o
o o o o o
o o o o o
o - o - o
color
color is calculated from the last 7 nibbles (28 bits) of the hash HHHSSLL:
the HHH (0..4095) value is remapped to a value between 0..360 degrees and is used as the hue
the SS (0..255) value is remapped to a value between 0..20 and is subtracted from a max saturation of 65 percent
the LL (0..255) is remapped to a value between 0..20 and is subtracted from a max lightness of 75 percent
in my case 30f4289:
0x30f is remapped to 68.83 degrees, which is my hue,
0x42 is remapped to 5.17, so my saturation is 65 - 5.17 == 59.83%,
0x89 is remapped to 10.74, so my luminance is 75 - 10.74 == 64.26%.
further these values are converted into the rgb color space resulting in #cada6d rgb color code
the combination of the pattern and color create the final identicon image
usage
all exported functions take data []byte and size int
data is used as input to md5.
note:
size is identicon pixel size (not final image size).
final image will be 6 x 6 pixels of given size
(that is a 5 x 5 matrix plus margins)
example
package main
import (
"fmt"
"github.com/asarandi/identicon"
)
func main() {
for i := 0; i <= 10; i++ {
s := fmt.Sprintf("%d", i)
identicon.File([]byte(s), 8, s+".png")
}
}
license
MIT
Documentation
Source Files