CONSTRUCTING RETINAL FUNDUS PHOTOMONTAGES - A NEW COMPUTER-BASED METHOD

Purpose. To develop computer algorithms for reconstructing 24-bit colo r, wide-angle composite retinal fundus images from a set of adjacent 4 5 degrees fundus slides, The authors present the description, technica l details, and results of the image reconstruction technique. Methods. Patients with retinal degeneration underwent fundus photography with a 45 degrees field-of-view fundus camera. Individual photographic slid es were digitized for creating fundus montages. Background variations in individual 45 degrees images were modeled to first- or second-order two-dimensional polynomial functions to generate a background image. The background image was subtracted from the original image to obtain background corrected image. Background corrected images were registere d and spatially transformed using a first- or second-order two-dimensi onal polynomial warp model to reconstruct a composite retinal fundus m ontage. Results. The authors successfully reconstructed 24-bit color, 100 degrees field-of-view, composite retinal fundus images. The comput er-reconstructed montages are an improvement over manually generated m ontages because computer analysis can be performed on the computer-bas ed montages. In addition, background variations and discontinuities be tween individual photographs observed in manually generated montages a re reduced greatly in computer-generated montages. Most important, the computer-generated montages are better aligned than the manually gene rated photomontages. Conclusions. This method of reconstructing a wide -angle composite retinal fundus image from a set of adjacent small- an d wide-angle fundus slides is a new tool for creating montages as larg e as 100 degrees field of view. The computer-generated montages may be used for documenting and quantifying retinal findings, This can great ly assist studies of retinal manifestations of diseases, such as gyrat e atrophy, retinitis pigmentosa, sickle cell disease, and acquired imm une deficiency syndrome.