[OPTICAL REVIEW Vol. 16, No. 6 (2009) 594-600]
© 2009 The Optical Society of Japan

Look-Up Table and Gaussian Filter-Based Inverse Halftoning Method Excellent in Gray-Scale Reproducibility of Details and Flat Regions

Noriaki SUETAKE*, Go TANAKA, and Eiji UCHINO

Graduate School of Science and Engineering, Yamaguchi University, Yamaguchi 753-8512, Japan

(Received March 23, 2009; Revised July 21, 2009; Accepted August 31, 2009)

Halftoning is a technique in which gray-scale images are converted into binary ones, and has been used widely in many practical image processing applications. On the other hand, inverse halftoning is a technique of reproducing a gray-scale image from a binary one. One of the sophisticated inverse halftoning methods which can yield a high quality gray-scale image is that based on a look-up table (LUT). In this paper, a new inverse halftoning method based on a combination of this LUT method and a Gaussian filter is discussed. Here, the output gray-scale image is reproduced by blending the output of the LUT-based inverse halftoning and that of the Gaussian filtering appropriately in accordance with local statistics of the image. The effectiveness and the validity of the described method are verified through experiments.

Key words: inverse halftoning, look-up table, Gaussian filter

*E-mail address: suetake@sci.yamaguchi-u.ac.jp