I believe that changing from 0-2 Volts to 2-4 Volts will not solve your problem. Because in the range 2-4V, 4 will be a high value to uC. What about 2Volt?

But in order to add a DC offset of +2 volt to your signal, you just connect a resistor (470 R) from your camera output to uC, and then on uC side of resistor, pull it up with 10 K variable. With this variable, you can adjust the amount of DC offset you want to add to your signal.

Instead you just use a NPN transistor as a switch with some 10 K load in collector lead and bias it with the VCC. Now use your signal to drive the base of this NPN with say 4.7K resistor. What you will get at the collector is

0V when signal is 2V
5V when signal is 0V

Regards

IA

Regards
IA