Detecting flash artifacts in fundus imagery

In a telemedicine environment for retinopathy screening, a quality check is needed on initial input images to ensure sufficient clarity for proper diagnosis. This is true whether the system uses human screeners or automated software for diagnosis. We present a method for the detection of flash artifacts found in retina images. We have collected a set of retina fundus imagery from February 2009 to August 2011 from several clinics in the mid-South region of the USA as part of a telemedical project. These images have been screened with a quality check that sometimes omits specific flash artifacts, which can be detrimental for automated detection of retina anomalies. A multi-step method for detecting flash artifacts in the center area of the retina was created by combining characteristic colorimetric information and morphological pattern matching. The flash detection was tested on a dataset of 5218 images representative of the population. The system achieved a sensitivity of 96.54% and specificity of 70.16% for the detection of the flash artifacts. The flash artifact detection can serve as a useful tool in quality screening of retina images in a telemedicine network. The detection can be expected to improve automated detection by either providing special handling for these images in combination with a flash mitigation or removal method.