Methods for structural characterization of particle films have been developed. Monodisperse silica particles with alkoxy chains grafted on the surface formed dense colloidal films at the air-liquid interface. The positions of the partly immersed particles were determined by light microscopy and image analysis. The average size of the ordered domains could be estimated from the pair distribution function. We were also able to determine the distribution of pores and defects in the colloidal film using Delaunay triangulation. The two methods were used to study the effect of interparticle bond strength on the film structure. We found that the size of the ordered domains decreased exponentially when the bond strength increased, while the pore density increased. The effect of drying on structural changes of the colloidal film was also discussed.