The circle on the left uses the built-in pen brightness block. The circle on the right uses a custom pen brightness block using a gamma of 2.2. The right circle should more closely match the color of the background. If the left circle matches the color of the background, it is due to a browser bug when scaling images. Enter fullscreen mode to prevent this bug from occurring. On cheap monitors, the right circle may appear to be significantly more blue than the background.
