Image-based CAPTCHA generation system
US7929805B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 30, 2007 |
| Grant date | Apr 19, 2011 |
| Priority date | — |
| Expiry date | Feb 7, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F21/36
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a system and method for the generation of attack-resistant, user-friendly, image-based CAPTCHAs (Completely Automated Public test to Tell Computers and Humans Apart), controlled distortions are applied to randomly chosen images and presented to a user for annotation from a given list of words. An image is presented that contains multiple connected but independent images with the borders between them distorted or otherwise visually obfuscated in a way that a computer cannot distinguish the borders and a user selects near the center of one of the images. The distortions are performed in a way that satisfies the incongruous requirements of low perceptual degradation and high resistance to attack by content-based image retrieval systems. Word choices are carefully generated to avoid ambiguity as well as to avoid attacks based on the choices themselves.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.