<td ng-repeat="user in data.users">
 <md-button class="md-raised md-primary" md-theme={{getTheme(time.check,user)}}>STATE</md-button>
</td>

    $scope.getTheme = function(check,user) {
      var hex = parseInt(check);
      var state = (hex >> user.id*8) & 0xff;
      switch(state) {
        case 0x00: /*FALSE*/
          return "red";
         case 0x01: /*TRUE*/
          return "green";
         case 0x10: /*MAYBE*/
          return "amber";
         case 0x11: /*DEFAULT (unclicked)*/
          return "grey";
         default:
          console.log("STATE: UNKNOWN");
          break;
      }
    }