Does the Found Image search take into account the monitor color profile? Will it still find the grabbed pixels if the color profile of the monitor has changed? Or the brightness?
You should try it and see .
IME, I have had no trouble running the KMacro Action "Found Image" on multiple computers and multiple monitors where each monitor is separately profiled and where the profiles are updated regularly. This only reports that it works under normal circumstances — where normal is using color profiles and monitor settings to achieve a color-correct workflow.
Note that monitor brightness doesn't come into the equation at all. Neither KM nor screen-capture utilities have any way to measure what your screen actually shows. They make their judgement from the instructions sent to the screen. (This is also why color-correction requires a hardware colorimeter and cannot accurately be done via software.)
The same may be true of monitor profiles — I'm going to guess that the profiles are applied past the point where the data is read by the Found Image Action. This makes sense: the data is "pure" — what your display does with it is another matter.
You can successfully run KMacros with the Found Image Action with monitor brightness turned to zero — the Action works with the screen un-illuminated.