(Red, Green, Blue are the decimal color values)
Difference in color
[Max(Red1,Red2)-Min(Red1,Red
2)] +
[Max(Green1,
Green2)-Min(Green1,Green2)] +
[Max(Blue1,
Blue2)-Min(Blue1,Blue2)]>500
Difference in brightness
((Red*299) + (Green*587) + (Blue*114)) /1000>125