Abstract
The quality of document images acquired by scanners is degraded by noise and lossy compression. Since the degradation of document images leads to deterioration of visibility and text recognition accuracy, color correction is an important process to improve the quality of document images. In this study, we propose a color correction method for two-color printed document images. The proposed method consists of hue correction and edge-preserving smoothing. The proposed method assumes that each pixel in a two-color printed document image has the same hue as the ink color or achromatic. Therefore, in an undegraded image, all pixels lie on a constant hue plane.
The proposed method first finds the constant hue plane with the minimum error and corrects the hue by projecting each pixel onto the constant hue plane. Next, edge-preserving smoothing is performed to suppress small changes in intensity and saturation in flat areas and thus remove noise-induced degradation. In experiments, proposed color correction is performed on document images to verify the effectiveness of the proposed method. The aim of this study is not to achieve perfect color reproduction of images acquired by a scanner but to convert them to natural-looking images with little degradation by performing color correction processing.
