Woof. I can't believe I got there! You can get most of the outside through intuition--if you need some help the 9 toward the bottom is evenly distributed relative to the other numbers it touches. For the center of the island, the 5s and 6 are each crossed by a 3 one pixel from the top, like a "t". There is a 5x5 "X" next to the bottom cross. this eliminates MOST of the ambiguity of the single pixels.