Protocol for the morphology analysis of SBS polymer modified bitumen images obtained by using fluorescent microscopy

Fluorescent technique has been used to characterise the morphology of polymer modified bitumen for years. However, the main problem of this technique is a missing standardised protocol for image capture factors and processing algorithms (CF&PA). The purpose of this study was to find out the effects of CF&PA on morphology and set up a protocol for morphological analysis of SBS polymer-modified bitumen (PMB) using the fluorescent microscopy technique. In order to set up this protocol, fluorescent images were captured and processed with different CF&PA. Capture factors mainly include magnification, exposure time and storage format while processing algorithms include noise reduction, enhancement and segmentation. Morphological and parametric analysis indicated that all images must be captured under the same exposure time and should not be processed by white balance. Besides, four principles should be followed to determine the optimal magnification. As to the image storage format, JPEG 2000 was selected to retain the most details. The proper neighbourhood level was obtained from the particle number curve to realise noise reduction. Compared with other complicated segmentation algorithms, threshold methods are more suitable because of the typical two-phase characteristic of PMB. Because of potential change in detailed information of original images, enhancement was not recommended. Finally, the image capturing and processing steps and their levels were given based on the discussion above.