Improved method of adaptive histogram equalization for color fundus images

The paper investigates the improvement of the visualization quality of color fundus images using the contrast-limited adaptive histogram equalization (CLAHE) method. The method is applied to the R, G, B channels of images from the HRF database. The results showed an increase in the average contrast, and visual analysis confirmed better visibility of fundus vessels while preserving local details. The proposed approach is effective for image preprocessing in medical diagnostics. The proposed CLAHE method by separately processing the R, G, B channels has demonstrated its effectiveness in enhancing the contrast of fundus images, as evidenced by an increase in the average contrast by 4.4% and better visibility of retinal vessels, especially in the green channel, and also helps to make abnormal structures such as neoplasms or hemorrhages more visible. However, the method causes a shift in the color balance, which may affect the diagnostic value of the images, and also enhances chromatic aberration at its borders.