Histogram equalization is a method used in image processing to improve the contrast of images. A new approach called Gray Value Retention Histogram Equalization based on MMTD has been developed to address the issue of losing image details in traditional histogram equalization. This method uses a measure called medium truth scale to decide whether to enhance high or low gray levels in the image. The images processed with this new method show better results compared to traditional histogram equalization, preserving more image details for improved quality.