Virtual microscopy: High resolution digital photomicrography as a tool forlight microscopy simulation

Recent advances in microcomputers and high resolution digital video cameras provide pathologists the opportunity to combine precision optics with digi tal imaging technology and develop ne cv educational and research tools. We review recent advances in virtual microscopy and describe techniques for v iewing digital images using a microcomputer-based workstation to simulate l ight microscopic examination, including scanning at low power to select fea tures of interest and zooming to increase magnification. Hardware and softw are components necessary to acquire digital images of histological and cyto logical slides, and closely simulate their examination under a light micros cope are discussed. The workstation is composed of a MicroLumina digital sc anning camera (Leaf Systems, Southborough, MA), light microscope (Olympus O ptical Co., Lake Success, NY), Pentium (Intel Corp., Santa Clara, CA) 166 M Hz microcomputer configured with 64 megabytes of random access memory (RAM) , a MGA Millenium Powerdesk graphics card (Matrox Graphics, Inc., Montreal, Canada) and Photoshop software (Adobe Systems Inc., San Jose, CA) running in a Windows 95 (Microsoft Corp., Redmond, WA) environment. Images with spa tial resolutions of up to 2700 x 3400 pixels in 36-bit color, can be displa yed simultaneously as distinct images in a montage, or merged into a single composite image file to highlight significant features of a histological o r cytological slide. These image files are saved in Joint Photographers Exp erts Group (JPEG) format using compression ratios of up to 80:1 without det ectable visual degradation. The advantages and technical limitations of var ious workstation components are addressed and applications of this technolo gy for pathology education, proficiency testing, telepathology, and databas e development are discussed. Copyright (C) 1999 by W.B. Saunders Company.