Quantitative analysis of colocalisation covers the quantitative aspects of spatial correlation of pixels in different channels of an 2D or 3D image. You can calculate the percentage of colocalisation and other values. Notice that the results are highly dependent on the quality of the input data (noise, signal level, bleaching, optical aberrations and channel alignment etc.) and the fraction of events choosen by your input.
Have a look at ImageJ colocalisation packages and many additional informations in: