Abstract: Methods and apparatus for a non-invasive test tool for testing and monitoring the interactions between an embedded microprocessor and its programs, various input analog and discrete electrical signals, and an LCD output display screen. The test tool uses a physical probe, preferably coupled in a non-invasive manner to the pins of the LCD display screen, and specialized hardware to capture the LCD output of the software-under-test as an event interaction between the microprocessor and various inputs. The captured LCD output is converted to a standard pixel format and stored for testing. The standard pixel format comprises a color and/or intensity value for each pixel position of interest, stored into a data structure. One embodiment uses a conversion which includes adding the time-modulated pixel data of a plurality of frames to generate a single composite frame having a color and/or intensity value for each pixel position of interest.