Photo sharing is increasingly popular, driven by social media platforms like Instagram and services such as Flickr and Google Photos. However, this growth has been accompanied by significant issues, particularly image theft. To address this issue, we introduce CAMPrints, a robust system for detecting image theft. CAMPrints verifies whether edited images found online contain camera fingerprints matching those of user-provided reference images. The system overcomes the challenges of identifying images altered by diverse image processing operations. We select a small yet representative set of operations by categorizing them based on their impact on pixel values and locations. A deep-learning model is trained to recognize and compare camera noise patterns pre- and post-editing. We conduct real-world evaluations involving 36 cameras across eight make-and-model combinations, along with over 40 image processing operations applied to more than 4,000 images. CAMPrints achieves an average AUC of 0.92, significantly outperforming the state-of-the-art methods by up to 1.8 times.

The prevalence of counterfeit infant formulas worldwide poses serious threats to infant health and safety, a concern highlighted by the notorious Melamine Milk Scandal that affected hundreds of thousands of children. The primary challenge in detecting counterfeit formulas lies in their sophisticated adulteration and substitution techniques. Such detection is feasible only in laboratory settings, making it nearly impossible for average consumers to test the formula before feeding their infants. To address this problem, we propose PowDew, a novel and practical system for detecting counterfeit infant formula that utilizes only a commodity smartphone. PowDew operates by capturing and analyzing the interaction of a water droplet with the powdered formula, focusing on the droplet motion, namely its spreading and penetration. Our insight is that the droplet motions are governed by powder-specific properties such as wettability and porosity. PowDew analyzes the subtle differences in droplet motions, and infers the formula's authenticity. To demonstrate PowDew's effectiveness, we implement PowDew and conduct comprehensive real-world experiments under varying conditions with different brands of powdered infant formula and adulterants. Our experiments result in a total of 12,000 minutes of video recordings of the droplet motions on various infant formulas, including authentic and altered. Our experiments demonstrate that PowDew yields an overall detection accuracy of up to 96.1%.

The rise of counterfeit powdered food products, exemplified by notorious incidents such as the Melamine Milk Scandal, poses significant risks to consumers. The primary challenge in identifying these counterfeit products comes from their intricate adulteration and substitution techniques. Currently, such identification methods are only viable in laboratory settings, making average consumers nearly impossible to authenticate their products. To address this limitation, we propose PowDew, a novel system that employs a smartphone to detect counterfeit powdered food products. PowDew utilizes the powder's physical property, namely droplet motion, as a basis for verification. Through real-world experiments, PowDew demonstrate a practicality with achieving an overall detection accuracy of up to 96.1%.

The demand for masks and air filters with effective filtration capabilities is skyrocketing as there are many applications that require protecting users from inhaling air pollutants or hazardous particles. Unfortunately, we are witnessing a surge in the number of counterfeit and substandard filters attributed to malicious and inept manufacturers. Hence, users are left vulnerable in not knowing which products are reliable. Exacerbating the problem, there are diverse filter standards, each with a unique expression for filtration efficiencies, adding to user confusion. Moreover, the average user lacks the necessary tools, techniques, and knowledge to independently verify the filtration efficiency. Specifically, state-of-the-art solutions are lab-based machines that are extremely expensive and difficult to access for the general public. To solve this problem, we propose FilterOp, a novel smartphone-based mask and filter testing system. FilterOp is a practical solution that allows a user to estimate the filtration efficiency of a mask or a filter using only a pair of commodity smartphones. The novelty of FilterOp comes from its use of light absorption and scattering effects, observed when light propagates through the filter. We evaluate FilterOp in comprehensive real-world experiments using 256 filter instances across 27 different make-and-model products with varying filtration efficiencies. Comparing our results to those obtained with a state-of-the-art government-certified testing machine, we observe that FilterOp yields comparable results with a low mean absolute error of 2.7%, and detects substandard products with an overall accuracy of 96%.

We are witnessing a surge in the reported cases of counterfeit liquid products in the market including olive oil, honey, and alcohol. Counterfeiters often adulterate the liquid products by replacing a large portion of the authentic content with cheaper substitutes (e.g., mixing vodka with cheaper alcohol or potentially toxic methanol). Exacerbating the problem, the counterfeits are packaged and sealed to factory standards, rendering it extremely difficult for an average consumer to identify them. While solutions exist, they are often impractical for the general public as they require specialized and costly equipment. To overcome these limitations, we propose LiquidHash, a novel counterfeit liquid food product detection system. LiquidHash is a practical solution that only requires the use of a commodity smartphone to detect adulterated liquid products without opening the bottles. LiquidHash works by detecting and tracking the shape and movement of air bubbles that form inside the bottles. We implement LiquidHash and evaluate its feasibility with real-world experiments under varying conditions with a total of more than 500 minutes of video recording and observe an overall detection accuracy of up to 95%.

Counterfeit liquid food products, including olive oil, honey and alcohol, are continuing to pose severe threats to the general public as counterfeiters adulterate the authentic content with cheaper and potentially harmful substitutes, and package them in authentic bottles. Existing solutions are often impractical for the general public as they require specialized and costly equipment as well as taking liquid samples. We overcome these limitations by proposing LiquidHash, a novel detection system that only requires the use of a commodity smartphone to detect adulterated liquid products without opening the bottles. LiquidHash leverages computer vision and machine learning techniques to extract characteristics of air bubbles formed by flipping a bottle. We implement LiquidHash and evaluate its feasibility with real-world experiments and achieve an overall detection accuracy of up to 95%.

Tiny hidden spy cameras concealed in sensitive locations including hotels and bathrooms are becoming a significant threat worldwide. These hidden cameras are easily purchasable and are extremely difficult to find with the naked eye due to their small form factor. The state-of-the-art solutions that aim to detect these cameras are limited as they require specialized equipment and yield low detection rates. Recent academic works propose to analyze the wireless traffic that hidden cameras generate. These proposals, however, are also limited because they assume wireless video streaming, while only being able to detect the presence of the hidden cameras, and not their locations. To overcome these limitations, we present LAPD, a novel hidden camera detection and localization system that leverages the time-of-flight (ToF) sensor on commodity smartphones. We implement LAPD as a smartphone app that emits laser signals from the ToF sensor, and use computer vision and machine learning techniques to locate the unique reflections from hidden cameras. We evaluate LAPD through comprehensive real-world experiments by recruiting 379 participants and observe that LAPD achieves an 88.9% hidden camera detection rate, while using just the naked eye yields only a 46.0% hidden camera detection rate.

Tiny spy cameras hidden in everyday objects are continuing to pose severe privacy threats to the general public as these cameras are often placed in sensitive locations such as hotels and restroom stalls. Commercially available "hidden camera detectors" have high false positive rates, and existing academic works detect (but cannot localize) only a subset of hidden cameras with wireless capabilities. We overcome these limitations by proposing LAPD, a novel hidden camera detection and localization system that leverages time-of-flight (ToF) sensors on commodity smartphones. LAPD is a smartphone app that detects hidden cameras in real-time by transmitting laser signals from the ToF sensor and searching for unique signatures representing reflections from hidden camera lenses. Using computer vision and machine learning techniques, LAPD achieves significantly higher hidden camera detection rates compared to the naked eye and hidden camera detectors.

In this paper, we discuss and evaluate the advantages and disadvantages of several techniques to visualize and analyze eye movement data tracked and recorded from public transport map viewers in a formerly conducted eye tracking experiment. Such techniques include heat maps and gaze stripes. To overcome the disadvantages and improve the effectiveness of those techniques, we present a viable solution that makes use of existing techniques such as heat maps and gaze stripes, as well as attention clouds which are inspired by the general concept of word clouds. We also develop a web application with interactive attention clouds, named the EyeCloud, to put theory into practice. The main objective of this paper is to help public transport map designers and producers gain feedback and insights on how the current design of the map can be further improved, by leveraging on the visualization tool. In addition, this visualization tool, the EyeCloud, can be easily extended to many other purposes with various types of data. It could be possibly applied to entertainment industries, for instance, to track the attention of the film audiences in order to improve the advertisements.