1. A method for detecting tampering in a document image, the method comprising: determining, by an image processing device, an image quality of the document image by analyzing one or more quality features extracted from the document image; pre-processing, by the image processing device, the document image based on a pre-defined ontology of documents when the image quality is above a pre-defined quality threshold; segmenting, by the image processing device, the pre-processed document image into one or more regions of interest based on the pre-defined ontology of documents; assigning, by the image processing device, a pre-defined weightage to a tampering in the one or more regions of interest; determining, by the image processing device, a weighted average of the pre-defined weightage for each tampering in the one or more regions of interest by processing each region of interest; and detecting, by the image processing device, tampering in the document image when a weighted average of the pre-defined weightage for each tampering in the one or more regions of interest is above a pre-defined threshold value.