Estimation of linear transformation by analyzing the periodicity of interpolation

• The proposed method estimates the linear transformation of an investigated image.
• The second derivatives for row and column directions exploit the periodicities.
• Both the magnitude and phase information of the derived signals are analyzed.

Linear transformation, such as rotation, scaling, or any combinations of geometric attacks, is among the most common forms of image manipulation. This letter proposes a forensic technique that estimates the linear transformation of an investigated image. We exploited the periodic properties of interpolation by the second-derivative of the transformed image in both the row and column directions. Both the magnitude and phase information of the derived signals were analyzed to estimate the transformation matrix accurately. Empirical evidence from a large database of manipulated images indicates the superior performance of the proposed method.