A method and system for extracting data signals from a scanned image resulting from optical, radiometric, or other types of analysis of a molecular array. The positions of corner features are first located. Then, an initial feature coordinate grid is determined from the positions of the corner features. A refined feature coordinate grid is then calculated based on the positions of strong features, and is used to identify the positions of weak features and the positions of the local background regions surrounding all features. Finally, signal intensity values are extracted from the features and their respective local background regions in the scanned image, and background-subtracted signal intensity values, background-subtracted and normalized signal intensity ratios, and variability information and confidence intervals are determined based on the extracted values.