With the advent of time, the number of images being captured and shared online has grown exponentially. The images which are captured are later accessed for the purpose of searching, classification and retrieval operation. Hence these images must be labelled with appropriate words, phrases or keywords so that the requisite operation can be performed efficiently. Automatic Image Tagging is such ...

Text CAPTCHA has been an effective means to protect online systems from spams and abuses caused by automatic scripts which pretend to be human beings. However, nearly all the Text CAPTCHA designs in nowadays are based on English characters, which may not be the most userfriendly option for non-English speakers. Therefore, under the background of globalization, there is an increasing interest in...

Over the last years, most websites where users can register (e.g., email providers and social networks) adopted CAPTCHAs (Completely Automated Public Turing test to tell Computers and Humans Apart) as a countermeasure for automated attacks. The battle of wits between designers and attackers of CAPTCHAs led to current ones being annoying and hard to resolve for users, while still being vulnerabl...

CAPTCHA has been widely deployed by commercial web sites as a security technology for purposes such as anti-spam. A common approach to evaluating the robustness of CAPTCHA is the use of machine learning techniques. Critical to this approach is the acquisition of an adequate set of labeled samples, on which the learning techniques are trained. However, such a sample labeling task is difficult fo...

A tagging sequence is used to assess MR image deformations before a stereotactic neurosurgical procedure, in a test model and in two patients. This pulse sequence super-imposes narrow parallel orthogonal tag lines on an image, which can be used as an internal reference frame. Image deformation is directly related to surface area variations in the squares produced by the tagging-sequence pulses....

This paper presents Tagasaurus a tool to help manually annotate image sets and create annotated collections. A key aspect of the workflow permitted by interface is that it records independent emotional value associations, pictorial textual annotations. version being showcased goes beyond previous approaches allowing user collections images under an entity tag. can corpus specific label which ne...

We explore the robustness and usability of movingimage object recognition (video) captchas, designing and implementing automated attacks based on computer vision techniques. Our approach is suitable for broad classes of moving-image captchas involving rigid objects. We first present an attack that defeats instances of such a captcha (NuCaptcha) representing the state-ofthe-art, involving dynami...

In this paper, we present a novel watermarking scheme to ensure the authenticity of digital images. Our authentication technique is able to detect malicious tampering of images even if they have been incidentally distorted by basic image processing operations. The image protection is achieved by the insertion of a secret author’s identification key in the image wavelet coefficients by their sel...