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Picture editing is prevalent across various fields, risking misinformation. This paper introduces a meticulous mathematical technique to distinguish true from false images by focusing on photomontage and false captioning methods and employing segmentation, classification, and common sense reasoning. Methods discussed include image segmentation, importance maps, ROI calculation, supervised and unsupervised classification, and reasoning to detect anomalies in images.
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Detecting False Captioning Using Common Sense Reasoning James Byrd
Abstract • Picture editing is popular • Medical, Journalism, Science all at risk • how do we detect what is real from what is not? • We shall introduce a nearly flawless mathematical technique to tell the true from the false
Intro • Pictures are a compelling way to communicate information • Why modify? • To make the picture tell a different story • “Yellow Journalism”
Photo Manipulation • 4 ways • Deletion of Details - deleting details • Insertion of Details - inserting additional details • Photomontage - combining multiple images • False Captioning - misrepresenting image content
This Paper’s Focus • Photomontage • False Captioning
Steps for detection • Segmentation • Classification • Common Sense Reasoning
Segmentation • Segment the image into regions • Make an “importance map” to compare across images in a given corpus
Classification • Perhaps the most important part • Segment based color scheme • compare segments among images
Common Sense Reasoning • 2 approaches • resolve local classification ambiguities within images; we will query a knowledge base to resolve proper relations • reason across a larger corpa of images to find unique or missing elements during an investigation
Methods • Image segmentation • Importance Map • Calculating ROIs • Classification • Reasoning
Image Segmentation • Segment the image • mean-shift image segmentation to decompose an image into homogeneous regions • choosing parameter values is often difficult • therefore we adds tons of colors and do many segmetns
Importance Map • to truly understand the importance of an image requires a thorough understanding of what the image contains and what the viewer needs • recognize objects (faces) and regions are important
Calculating ROI • 2 step process • Identify Candidate ROI • minimal image that identifies key important parts of the image • Grow the ROI • combine the ROI by using a clustering algorithm recursively
Classification • Supervised Classification • Training Sites - predetermined objects of interest in an image • Software uses these to create a “signature analysis” • Unsupervised Classification • Takes a large number of ROI and divides them into classes based on grouping in them • becoming increasingly popular
Reasoning • Resolve local ambiguities within an image • Answer questions the program has • i.e. water versus sky • Then the software determines if the anomalies are consistent across images or show signs of tampering • More pictures to examine are better for consistency
Conclusion • methods are limited by the performance of the components of image segmentation and important object identification