Environmental factors such as temperature and humidity influence the efficacyo fd efect imaging procedures based on the identification of changes between an intact state and the current state of as ample/component/structure in the presence of ad efect. In this paper,w ef ocus on the Reconstruction Algorithm for Probabilistic Inspection of Damage (RAPID)a nd propose an onlinear Lamb wave version of RAPID to visualize a delamination in acomposite structure without having to knowanything about the intact state, i.e. abaseline free RAPID. Once the optimal frequencyselection of Lamb wavesinapitch-catch configuration mode is performed, lowa nd high excitation amplitude signal responses within as parse array at that frequencya re evaluated along each transducer-receiverpath by analyzing aset of damage sensitive parameters: the correlation coefficient, the energy of the scaling subtracted signal, and the third harmonic ratio. Processing of this information leads to acorresponding probabilistic damage map of the area within the sparse array.The obtained results from av alidation experiment demonstrate the capability of this nonlinear variant of RAPID for the identification of adelamination in acomposite structure.