CIE Transformation: Why are custom values used

[jrast]

As I understand the Code, the cie function is used to transform the RGB image to grayscale. Why are custom values used and not the default ones, for example provided on the wikipedia page, which would be

0.2126 * R + 0.7152 * G + 0.0722 * B

smartcrop.js/smartcrop.js

Line 562 in 11614e1

return 0.5126 * b + 0.7152 * g + 0.0722 * r;

https://en.wikipedia.org/wiki/Grayscale

[jrast]

Sorry, just seen issue #77 which asks exactly the same question...