We present a generic and robust image analysis approach applicable to image data resulting from a broad class of hybridization experiments. The ultimate image analysis goal is to automatically assign a quantity to every array element (spot), giving information about the hybridization signal. Irrespective of the quantification strategy, the most important preliminary information to extract about a spot is the mapping between its location in the digital image and its position in the spot grid (grid fitting). We present a grid fitting approach divided into a spot amplification step (matched filter), a rotation estimation step (Radon transform) and a grid spanning step. Quantification of the hybridization signals is performed with different fitting approaches. The primary approach is a robust fitting of a parametric model with the help of M-estimators. The main advantage of parametric spot fitting is its ability to cope with overlapping spots. If the goodness-of-fit is too bad, a semi-parametric spot fitting is employed.