>>2176897I did
>>2176463One thing to try is to start using vectors. Once you have the selection, instruct your program to make a vector (or a path, in GIMP) from the outline of the selection. Pic related from when I just selected all the clear tiles in your image.
Then, you can make ad hoc changes, which unlike the lasso can be undone, to the vector so that it can sharply capture all those gay shark fins. You can also make a new, clear layer and render a line on it from the vector, and use the alpha channel of that line to generate a new, very smooth selection of the borders, with which you can purge all the off-color bleeding from the old background, expand or retreat the borders neatly, et al
