Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!spdcc!m2c!applix!scott From: scott@applix.UUCP (Scott Evernden) Newsgroups: comp.graphics Subject: Scaling dithered images Message-ID: <627@applix.UUCP> Date: Tue, 1-Dec-87 13:10:34 EST Article-I.D.: applix.627 Posted: Tue Dec 1 13:10:34 1987 Date-Received: Fri, 4-Dec-87 07:10:06 EST Reply-To: scott@applix.UUCP (Scott Evernden) Organization: APPLiX Inc., Westboro MA Lines: 24 I have a 300dpi monochromatic image from a MicroTek scanner. The image is a halftone, meaning the scanner has imposed a regular dither pattern (variable: 2x2 to 8x8) to achieve grey scale. I want to display this image on an approx. 75dpi screen. Currently, I take the simple approach of resampling the original image according to the scale factor (300/75) and read the value of the closest pixel. As you might guess, some very bad artifacting occurs. I suppose I could average the pixels in the vicinity of the sample location and maybe reduce my problem. Question is: does anyone have any neat ideas or references on how to display hi-res dithered images on a low-res screen at any scale factor? I'm looking for image scaling algorithms which can avoid the artifacting problem. Ideally, the algorithm should be amenable to rotation and shearing transforms as well. -scott