“…Recent research has compared traditional 1D time-series data approaches with image encoding techniques, presenting findings that substantiate the superior efficacy of image encoding methods [ 17 , 18 ]. Representative image encoding techniques include recurrence plot (RP) [ 19 , 20 , 21 , 22 , 23 ], Gramian angular field (GAF) [ 14 , 24 , 25 , 26 , 27 ], Markov transition field (MTF) [ 28 , 29 , 30 ], spectrogram (SP) [ 31 , 32 ], and scalogram (SC) [ 33 , 34 ]. These image encoding techniques have recently been applied in research that converts time-series data from vibration and current signals, collected for diagnosing faults in robots and various machinery (such as bearings, gearboxes, rotating machinery, complex distribution networks, ventilation, and air conditioning systems), into images for various convolutional neural network (CNN) models.…”