Fig. 1. PL detection and acquisition patterns

Fig. 2. Hidden crack patterns under different external ambient lighting

Fig. 3. PL detection system for photovoltaic panels in bright environment

Fig. 4. Relationship between grayscale values and image sequences

Fig. 5. Patterns collected by camera directly under modulation signals

Fig. 6. Schematic diagram of 4×1 window construction

Fig. 7. Schematic diagram of data parallel processing

Fig. 8. Flow chart of effective signal selection

Fig. 9. Comparison diagram of algorithm extracted in real time under different lighting