Know if a text on a dynamic background colour must be black or white to be easy to read

DarkOrLightColour.java

int color = palette.getVibrantColor(defaultColor);
int r = (color >> 16) & 0xFF;
int g = (color >> 8) & 0xFF;
int b = (color >> 0) & 0xFF;

row.setBackgroundColor(color);

//@see http://stackoverflow.com/questions/12043187/how-to-check-if-hex-color-is-too-black
double luma = 0.2126 * r + 0.7152 * g + 0.0722 * b; 

if (luma < 200) { //a magic number chosen with alexbailon.com, the lovely graphic designer 
    text.setTextColor(Color.rgb(255, 255, 255)); //a bright colour
} else {
    text.setTextColor(Color.rgb(0, 0, 0)); //a dark colour
}