IMAGE ENHANCEMENT TECHNIQUES FOR TELE-SLIT LAMP MICROSCOPY
Abstract
Ophthalmologists need an Eye-Tele analyzer that has a high-resolution image and no light reflection.A Slit lamp microscope, which is the main part of Eye-Tele analyzer, can be improved by implementing the function of an auto focus system, eye-tracking system, and image enhancement method. The focus position is the position that gives the maximum focus value. However there flection of light from the slit lamp can cause an error in finding the focus value algorithm. The reflection must first be identified and removed before calculating the focus values. The simulation result shows that the proposed algorithm can give the right focus position with trade off on computational time. Since the human eye is a spherical shape, slit lamp microscopy will focus only on a small part of the eye or only on the area of interest. To get an entirely sharp image, where all parts of the eye are in focus, a set of sharp eye images in different areas is needed to make the image mosaic method. This mosaic method can improve the resolution of the overall image. However, some sets of eye images are taken under different lighting conditions, which can lead to false mosaicking.The processing time is extremely long to process. To solve this problem, the gradient orientation pattern matching technique (GOPM) is used to eliminate the undistributed light intensity. The coarse-to-fine gray-scale matching strategy is introduced to reduce the computational time. The results show that the uses of GOPM help the mosaicking process, to give an accurate matching position which is very important for the image enhancement process. Also, the processing time is remarkably reduced.
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