Exponentially smoothed Fujii index for online imaging of biospeckle spatial activity

•An algorithm for the real-time evaluation of biospeckle activity was developed.•The exponentially smoothed Fujii method was compared with the conventional methods.•The algorithm was tested using the data of apple fruit with a fungal infection.•The proposed method showed similar or better results than the conventional methods.

This paper describes a simple and efficient approach for the real-time evaluation of biospeckle spatial activity using a live video stream. The proposed method combines the exponentially weighted averaging of time-series data with a calculation of the Fujii biospeckle activity index. The exponentially smoothed Fujii method (ESF) was compared with the conventional offline method. A comparison was carried out using the speckle data of apple fruit with a fungal infection. Using data from a model experiment it was shown that the proposed method is capable of producing consistent and reliable results which are comparable with results obtained using the conventional approach. The exponentially smoothed Fujii method (ESF) provided high contrast maps of biospeckle activity without any loss of resolution. Reasonable computational demands made the practical implementation of this method possible using a standard desktop computer.