International Journal of Software Engineering and Its Applications Vol. 10, No. 1 (2016), pp. 15-26 http://dx.doi.org/10.14257/ijseia.2016.10.1.02 ISSN: 1738-9984 IJSEIA Copyright ⓒ 2016 SERSC Grayscale Conversion of Histopathological Slide Images as a Preprocessing Step for Image Segmentation Jashojit Mukherjee 1 , Indra K. Maitra 2 , Kashi Nath Dey 1 , Samir K. Bandyopadhyay 1 , Debnath Bhattacharyya 3 and Tai-Hoon Kim 4* 1 Department of Computer Science and Engineering, University of Calcutta, India 2 B. P. Poddar Institute of Management and Technology, Kolkata, India 3 Department of Information Technology, Bharati Vidyapeeth Deemed University College of Engineering, Pune, India 4 Sungshin Women's University, Dongseon-dong 3-ga, Seoul, Korea jashojitmukherjee@gmail.com, ikm.1975@ieee.org, kndey55@gmail.com, skb1@vsnl.com, debnathb@gmail.com, taihoonn@daum.net Abstract This paper presents a method of conversion of color image of histopathological slides to grayscale as a preprocessing step for image segmentation. The method utilizes characteristics of these images to reduce the amount of information lost during the conversion. It is a global mapping scheme and the same color does not map to two different grayscale values. Color information is added to the brightness information to reduce information loss and the weights for the added color are dependent on the distribution of the pixels in a particular image. The method was tested on a large set of histopathological slide images and convincing results were obtained some of which has been published in this paper. Keywords: Histopathological slides, Grayscaling, CIE Lab colorspace, Luminance and Hue 1. Introduction Histopathology refers to the microscopic examination of tissue in order to study the manifestations of disease. A tissue sample is extracted from the affected area and is placed on a glass slide. Often it is treated with some chemicals and stains to make features more distinguishable. This sample is then observed by a pathologist under a microscope to make a diagnosis. (a) (b) (c ) Figure 1. (a) A Histopathological Slide Image, (b) Its Grayscale Image when Converted by Standard Method, (c) Result of Conversion by Proposed Method * Corresponding Author