I want to draw fake pictures

In this competition, my understanding of lag is that in painting, thinking is the first step, but I always conceive a contour in my mind and cannot imagine the picture completely. In this game, you can use a paintbrush to draw a portrait of a pen, but the traces you have drawn quickly disappear. After the "brain conception" is completed, you can only see a black outline, and then you can reproduce it step by step according to the traces you have drawn.