With the advancement of technology, there has been a tremendous rise in the volume of captured and distributed content. Image acquisition can be done with the help of scanners, cameras, smart phones, tablets etc. Document retrieval and recognition systems require high quality document images but most of the time, the images acquired suffer from various degradations like blur, uneven illumination, low resolution etc. To reduce the processing time and get good results, we require methods to evaluate and improve the quality of such images. This paper reviews the quality assessment methods and enhancement techniques for document images. It presents a survey of the work that has been performed in the field of document image quality assessment and enhancement.