"Find the Odd Disk" presents a visual puzzle where players must identify a single, subtly different colored disk among a grid of seemingly identical ones. The difference in color is minimal, challenging the player's perception and requiring careful observation. The game provides no hints or feedback beyond the user's clicks, increasing the difficulty and rewarding attentive analysis. Successfully clicking the odd disk reveals the next level, featuring progressively more disks and subtler color variations, making each round more demanding than the last.
Bruno Postle's "Piranesi's Perspective Trick" explores how 18th-century Italian artist Giovanni Battista Piranesi created the illusion of vast, impossible spaces in his etchings. Piranesi achieved this not through complex mathematical perspective but by subtly shifting the vanishing points and manipulating the scale of elements within a scene. By strategically placing smaller figures and architectural details in the foreground against exaggeratedly large background elements, and by employing multiple, inconsistent vanishing points, Piranesi generated a sense of immense depth and disorienting grandeur that transcends traditional perspective rules. This artistic sleight-of-hand contributes to the dreamlike and often unsettling atmosphere of his famous "Carceri" (Prisons) series and other works.
Commenters on Hacker News largely discussed the plausibility and effectiveness of Piranesi's supposed perspective trick, as described in the Medium article. Some debated whether the "trick" was intentional or simply a result of his artistic style and the limitations of etching. One commenter suggested Piranesi's unique perspective contributes to the unsettling and dreamlike atmosphere of his works, rather than being a deliberate deception. Others pointed out that the described "trick" is a common technique in perspective drawing, particularly in stage design, to exaggerate depth and create a sense of grandeur. Several commenters also shared links to other analyses of Piranesi's work and the mathematics of perspective. A few expressed appreciation for the article introducing them to Piranesi's art.
This post showcases a "lenticular" QR code that displays different content depending on the viewing angle. By precisely arranging two distinct QR code patterns within a single image, the creator effectively tricked standard QR code readers. When viewed head-on, the QR code directs users to the intended, legitimate destination. However, when viewed from a slightly different angle, the second, hidden QR code becomes readable, redirecting the user to an "adversarial" or unintended destination. This demonstrates a potential security vulnerability where malicious QR codes could mislead users into visiting harmful websites while appearing to link to safe ones.
Hacker News commenters discuss various aspects of the QR code attack described, focusing on its practicality and implications. Several highlight the difficulty of aligning a camera perfectly to trigger the attack, suggesting it's less a realistic threat and more a clever proof of concept. The potential for similar attacks using other mediums, such as NFC tags, is also explored. Some users debate the definition of "adversarial attack" in this context, arguing it doesn't fit the typical machine learning definition. Others delve into the feasibility of detection, proposing methods like analyzing slight color variations or inconsistencies in the printing to identify manipulated QR codes. Finally, there's a discussion about the trust implications and whether users should scan QR codes displayed on potentially compromised surfaces like public screens.
Summary of Comments ( 106 )
https://news.ycombinator.com/item?id=43745868
HN users generally enjoyed the "Find the Odd Disk" color puzzle, praising its elegant simplicity and clever design. Several pointed out the effectiveness of using just noticeable differences (JNDs) in color to create a challenging but solvable puzzle. Some discussed optimal strategies, with one suggesting binary search as the most efficient approach. A few users shared their completion times, and others expressed their satisfaction in solving it. There was some light debate over whether it was truly JND or slightly larger differences, but the overall consensus was positive, with many appreciating the break from more complex or stressful topics typically discussed on HN.
The Hacker News post "Find the Odd Disk" with ID 43745868, referring to the article about a color perception puzzle, has a modest number of comments, generating a brief discussion around the puzzle and related topics.
Several commenters discuss strategies for solving the puzzle. One commenter suggests a systematic approach, recommending starting by comparing the top-left disk to its neighbors and then systematically comparing adjacent disks, noting that the difference might be subtle. Another suggests a more visual approach, stating that squinting can help exaggerate the color difference. A third commenter explains their method, mentioning that they focused on the center of each disc, noticing a slight but consistent difference in the "odd" disk's color.
Beyond solution strategies, one commenter goes deeper into the science of color perception, mentioning the concept of "just noticeable difference" (JND) and how it plays a role in the difficulty of the puzzle. They discuss how the puzzle leverages subtle differences in color that are close to the JND threshold, making the odd disk challenging to identify.
A couple of commenters share their personal experiences with the puzzle. One admits to struggling with the puzzle, despite generally having good color vision. Another mentions finding the mobile version easier due to the increased color saturation on their screen.
Finally, one commenter draws a parallel between the puzzle and real-world applications, suggesting it's a good analogy for the challenges faced in tasks like identifying anomalies in large datasets. They point out that the subtle difference in the disk colors mirrors the subtle differences in data that can indicate important, yet easily overlooked, patterns or problems.
In summary, the comments on the Hacker News post primarily revolve around strategies for solving the color puzzle, discussions of color perception principles, and reflections on personal experiences with the puzzle, with a touch of relating the puzzle to real-world problem-solving. The conversation remains focused and relevant to the original post, offering different perspectives without veering into unrelated tangents.