A regular auto clicker repeats taps at fixed coordinates: you mark a point and it hits that point on a timer. That works while nothing moves. One ad opening, one extra item in a list or a different resolution is enough to send the tap somewhere else, and the sequence carries on as if it had worked.
An image auto clicker reverses the order. You crop the element that matters, a button, an icon, a health bar, and the automation looks for that element in the captured screen. The tap coordinate is computed at run time, from wherever the element actually is. If it moved, the tap follows. If it is not on screen, the condition is simply not met and the macro taps nothing.
Emulo is that idea in two apps that share one account: EmuloMobile, which runs inside Android itself, and EmuloAgent, which runs on Windows and drives emulators from outside. The detection engine is the same in both: image, text and color.