Retinal images are routinely acquired and assessed to provide diagnostic for many important diseases like diabetic retinopathy. People with proliferative retinopathy can reduce their risk of blindness by 95 percent with timely treatment and appropriate follow-up care. The color constancy is used in this context to define the ability of the visual system to estimate an object color transmitting an unpredictable spectrum to the eyes. In this paper, a Gray World method was proposed by assuming the average of the surface reflectance of a typical scene is some pre-specified value. The main idea based on illumination estimated using the statistical region data. The effectiveness of the Gray Word method and normal gray technique was calculated by using Mean Square Error (MSE) and Peak Signal to Noise Ratio (PSNR). The Gray World achieved the highest PSNR and lowest MSE proved that the image quality was improved. The proposed method can be used to help the ophthalmologist to detect a lesion in the retinal image automatically. Through the contrast variation in retinal images, the disease can be recognized very well.
