A combined effect of local and global method for contrast image enhancement

Abstract

Image enhancement is used to improve the digital quality of image. It is used to improve the poor quality of image that is too used to improve bad quality of picture into good picture or image. This paper suggests a combination of local and global method for contrast image enhancement. Global contrast image enhancement improves low contrast of image in a global way. This type of global enhancement avoids noise and other ringing artifacts of a digital image. In global contrast image enhancement when high contrast occurs it causes under exposure on some part of image and over exposure on some other part of an image. Global contrast image enhancement has much advantage but it lack in local enhancement of image means it lacks the local detail of an image. When we use local detail of an image, the local detail of an image can be defined in better way. Local contrast image enhancement increases noise of an image when high contrast gain occurs. When we use global contrast image enhancement or local contrast image enhancement single handedly it is not beneficial but when we use combination of local and global method it gives us better results for certain images. In this paper we will going to use global contrast stretching method for global contrast image enhancement. In local contrast image enhancement method we are using unsharp masking technique to enhance the local detail of an image. The main aim of using this combination of local and global method is to preserve the brightness of an image when contrast image enhancement is done.