In global enhancement techniques, each pixel of an image is transformed following a single transformation function. The existing contrast enhancement techniques can be categorized into three groups: global, local, and hybrid techniques.

This paper mainly focuses on contrast enhancement for different types of images. Įnhancement covers different aspects of image correction such as saturation, sharpness, denoising, tonal adjustment, tonal balance, and contrast correction/enhancement.

Furthermore, image enhancement is needed because of its wide range of application in areas such as atmospheric sciences, astrophotography, medical image processing, satellite image analysis, texture analysis and synthesis, remote sensing, digital photography, surveillance, and video processing applications. In many cases, these images might demand enhancement for making them more acceptable to the common people. These images are often affected by atmospheric changes, the poor quality of the image-capturing devices, the lack of operator expertise, etc. Since digital cameras have become inexpensive, people have been capturing a large number of images in everyday life. Extensive experiments along with qualitative and quantitative evaluations show that the performance of AGC is better than other state-of-the-art techniques. Afterwards, an adaptive gamma correction (AGC) is proposed to appropriately enhance the contrast of the image where the parameters of AGC are set dynamically based on the image information. Hence, we classify images into several classes based on the statistical information of the respective images. These methods do not consider the nature of the image, whereas different types of degraded images may demand different types of treatments. Most of the existing methods mainly focus on either global or local enhancement that might not be suitable for all types of images. In spite of much advancement in imaging science, captured images do not always fulfill users’ expectations of clear and soothing views. Due to the limitations of image-capturing devices or the presence of a non-ideal environment, the quality of digital images may get degraded.

How to increase gamma