Image-based CAPTCHA generation system
First Claim
1. A method of generating a Completely Automated Public test to Tell Computers and Humans Apart (CAPTCHA), comprising the steps of:
- storing a database of images and annotations corresponding to the images, each image depicting a concept or object intended for human recognition;
distorting at least one of the images, and presenting the distorted image on a computer display along with a separate list of words, one of which best annotates the distorted image; and
assuming that the user of the computer is a human as opposed to a machine if the correct word is selected to annotate the distorted image.
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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.
357 Citations
15 Claims
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1. A method of generating a Completely Automated Public test to Tell Computers and Humans Apart (CAPTCHA), comprising the steps of:
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storing a database of images and annotations corresponding to the images, each image depicting a concept or object intended for human recognition; distorting at least one of the images, and presenting the distorted image on a computer display along with a separate list of words, one of which best annotates the distorted image; and
assuming that the user of the computer is a human as opposed to a machine if the correct word is selected to annotate the distorted image. - View Dependent Claims (2, 3, 4, 5)
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6. A method of generating a Completely Automated Public test to Tell Computers and Humans Apart (CAPTCHA), comprising the steps of:
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storing a database of images and annotations corresponding to the images, each image depicting a concept or object intended for human recognition; presenting a composite image on a computer display, the composite image including plurality of different images randomly selected from the database; selecting one of the images from the composite image; distorting the selected image and presenting the distorted image along with a separate list of words, one of which best annotates the distorted image; and assuming that the recipient of the image is a human as opposed to a machine if the correct word is selected to annotate the distorted image. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A Completely Automated Public test to Tell Computers and Humans Apart (CAPTCHA) system, comprising:
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a database for storing annotated images, each image depicting a concept or object intended for human recognition; a processor for distorting the images; a display for presenting a distorted image to a user along with a separate list of annotations to choose from; and an input allowing a user to select the annotation that best corresponds to the distorted image. - View Dependent Claims (13, 14, 15)
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Specification