Phase contrast using a differentiated absolute contrast method

A depth retrieval technique based on phase contrast calculations by pulsed phase thermography (PPT) has been previously reported. The phase contrast requires an appropriate selection of the sound area. This is rarely an easy task primarily because a nondefective zone is not always a priori known and even when it is, some variability is typically observed in the results due to changes in the sound phase. This article proposes implementing the differentiated absolute contrast (DAC) method to eliminate the need of defining a sound area. The proposed PPT-DAC approach, allows computation of the phase contrast by subtracting the ideal phase value of a pixel from its measured phase.