Originally I made this for my own amusement, but I’ve gotten positive feedback on it from several people that tried it, so I’ve added it to the Google Play Store. Match the color of the top box by using sliders to adjust RGB values of the bottom box. A perfect score is 150.

 

No ads, no fee. Have fun! 

Link: https://play.google.com/store/apps/details?id=com.jsa.colormatch