© 2019 IEEE. Digital image processing (DIP) is carried out to produce an altered image that is more suitable for the intended application. Image filtering and image warping are considered to be the most common methods of image processing. Within image filtering, these operations are carried out to aid the altering or enhancing an image to either remove specific features or highlight features of interest within the image. These operations are generally carried out in the pre-processing stage and can have very positive results on the quality of feature extraction and the results of image analysis. This paper aims to give a brief overview of some popular image filtering operations, focusing on edge detection filters, smoothing filters and the advantages of greyscale over colour images.