DIM Electronic Advance Ignition

Here is a real time plot of the engine RPM (red), Ignition timing (green), and manifold pressure in (blue). The RPM is simulated by a second micro-controller, it starts with cranking speed, followed by idle, followed by increasing RPM from idle to 6000 RPM in under 4 seconds. A mighty-vac was used to provide the change in manifold pressure. The stair steps in the pressure is the result of small pumps to increase pressure. In a normal engine at WOT, the vacuum drops to zero. For reference the maximum timing is 10 base, plus 26 RPM, plus 12 vacuum. At WOT the timing is 36 degrees. Also at idle, the distributor port will be used, it will not provide significant vacuum at closed throttle. The blue plot is absolute manifold pressure, it reads inverted compared to vacuum. On the left is atmosphere, after the stair-step is maximum vacuum or about 0.02 ATM

I took a snap-shot of only a part of of the screen in an attempt to get a better view. Still not happy with screen capture, then MS paint to crop. Is there a better way?