An arbitrary scale image enlargement method with the prediction of high-frequency components.

Enlargement of digital images is equivalent to narrowing the sampling spacing. Hence, it is necessary for enlargement of the digital images to estimate the high-frequency components lost in the sampling by some means. Recently, an enlargement method accompanied by estimation of lost high-frequency components has been proposed. The present authors have also noted the Laplacian pyramid layer expression, which is a multiresolution representation of digital images, and have proposed an enlargement method to estimate lost high-frequency components. Based on the Laplacian pyramid layered representation, estimation of unknown high-frequency components is equivalent to estimation of unknown high-resolution Laplacian components. Since the layered expression of the Laplacian pyramid has band division encoding as the objective, the image size between the layers is 2 and the enlargement method based on this expression is also limited to 2. However, it is possible to obtain a layered expression with an arbitrary size ratio by varying the passband width of the Gaussian filter and eliminating the pixels corresponding to the bandwidth, in place of continuous use of the half-band Gaussian filter and downsampling of the usual Laplacian pyramid layered image. In this paper, based on this concept, an enlargement method with high-frequency component estimation that allows setting of an arbitrary enlargement rate is proposed. The effectiveness of the proposed method is clarified from abundant application examples. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(8): 41–51, 2003; Published online in Wiley InterScience (<URL>www.interscience.wiley.com</URL>). DOI 10.1002/ecjc.10018 [ABSTRACT FROM AUTHOR]