A method to quantify co-localization in biological images

Quantitative co-localization analysis with fluorescent microscopy is a common approach to assess the spatial co-ordination of molecules and thus to understand their functions in biological processes. However, the co-localization analysis results might not be consistent due to various imaging conditions and different quantification methods used. We propose a novel method to separate a co-localization event into two aspects: co-occurrence and intensity correlation, which are usually combined as one parameter in other quantitative co-localization analyses. By examining co-localization through both co-occurrence and intensity correlation, the co-localization analysis provides accurate and interpretable results. Furthermore, the co-occurrence pixels can be visualized in an additional image channel to provide an intuitive impression of the quantity and locations of the co-localization events occurring.