In recent years, digital forensics emerged as a powerful and promising discipline to identify, detect and authenticate the digital images. This could be the authentic ground to present a proof of tempering as evidence in the court of law. The trust we have had till now in believing what we see started eroding. This is all happening due to the availability of the low cost, sophisticated yet easy to use tools and techniques. Due to the availability of these tools tempering the digital photographs getting easier and easier but at the same time it's very difficult to detect traces, if viewed by necked eye. Image forensic tools are mainly classified based on the approach used; active or passive. We here present a survey on pixel-based and format-based techniques, which comes under the realm of passive approach for digital image forgery detection.

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Digital Image Forensics Image Processing Image Tempering