Host: The Institute of Image Electronics Engineers of Japan
This paper proposes a new approach for precisely and stably detecting changes in image scaling factor. DFT amplitudes for reference and input images are first transformed to the polar expressions. In the transformation, the cause of detection errors is analyzed and optimal frequency filtering for reducing errors is found. The position shift between the polar spectrum is detected by our PSA method. The weight function effective for accurate detection of the shift is discussed. The approach is applied for detecting changes of image scaling for four typical types of images. It becomes clear that the scaling factor can be detected with higher accuracy than that of the conventional method. The accuracy dependences on the patterns and scaling factor are also made clear and discussed.
