There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

As one of the most successful applications of image analysis and understanding, face recognition has recently received significant attention, especially during the past several years. At least two reasons account for this trend: the first is the wide range of commercial and law enforcement applications, and the second is the availability of feasible technologies after 30 years of research. Even though current machine recognition systems have reached a certain level of maturity, their success is limited by the conditions imposed by many real applications. For example, recognition of face images acquired in an outdoor environment with changes in illumination and/or pose remains a largely unsolved problem. In other words, current systems are still far away from the capability of the human perception system.This paper provides an up-to-date critical survey of still- and video-based face recognition research. There are two underlying motivations for us to write this survey paper: the first is to provide an up-to-date review of the existing literature, and the second is to offer some insights into the studies of machine recognition of faces. To provide a comprehensive survey, we not only categorize existing recognition techniques but also present detailed descriptions of representative methods within each category. In addition, relevant topics such as psychophysical studies, system evaluation, and issues of illumination and pose variation are covered.

Face recognition: A literature survey

“Unpaired Image-to-Image Translation using Cycle-Consistent Adversarial Networks”の学習報告

Images containing faces are essential to intelligent vision-based human-computer interaction, and research efforts in face processing include face recognition, face tracking, pose estimation and expression recognition. However, many reported methods assume that the faces in an image or an image sequence have been identified and localized. To build fully automated systems that analyze the information contained in face images, robust and efficient face detection algorithms are required. Given a single image, the goal of face detection is to identify all image regions which contain a face, regardless of its 3D position, orientation and lighting conditions. Such a problem is challenging because faces are non-rigid and have a high degree of variability in size, shape, color and texture. Numerous techniques have been developed to detect faces in a single image, and the purpose of this paper is to categorize and evaluate these algorithms. We also discuss relevant issues such as data collection, evaluation metrics and benchmarking. After analyzing these algorithms and identifying their limitations, we conclude with several promising directions for future research.

/pdf/detecting-faces-in-images-a-survey-4yhbbns6mr.pdf

Detecting faces in images: a survey

Optimum nonlinear signal detection and estimation in the presence of ultrasonic speckle.

In this paper we propose an image watermarking algorithm based on constraints in the Discrete Cosine Transform (DCT) domain. An image watermarking algorithm has two stages: signature casting (embedding) and signature detection. In the first stage it embeds an identifying label in the image. This is recognized in the second stage. The proposed algorithm has two processing steps. In the first step certain pixel blocks are selected using a set of parameters while in the second step a DCT coefficient constraint is embedded in the selected blocks. Two different constraint rules are suggested for the parametric modification of the DCT frequency coefficients. The first one embeds a linear constraint among certain selected DCT coefficients and the second defines circular detection regions according to the given parameters. The watermarks cast by the proposed algorithm are resistant to JPEG compression and filtering.

/pdf/image-watermarking-using-block-site-selection-and-dct-domain-3c21qx8u0m.pdf

Image watermarking using block site selection and DCT domain constraints.

A blind method for watermarking of vector graphics images through polygonal line modification is proposed. The watermark is embedded in the Fourier descriptors of the polygonal lines, causing invisible distortions to the vertices coordinates. The properties of the Fourier descriptors ensure that watermarks generated by this technique withstand rotation, translation, scaling, reflection, change of traversal starting point/direction and smoothing.

Fourier descriptors watermarking of vector graphics images

Morphological shape representation

Six basic facial expressions are investigated when the human face is partially occluded, i.e. when the eyes and eyebrows or the mouth regions are occluded. Such occlusions occur when a person wears glasses (e.g. in VR application) or a mouth mask (e.g. in medical application). More specifically, we are interested in finding the part of the face that contains sufficient information in order to correctly classify these six expressions. Two facial image databases are employed in our experiments. Each image from the database is convolved with a set of Gabor filters having various orientations and frequencies. The new feature vectors are classified by using a maximum correlation classifier and the cosine similarity measure approaches. We find that, overall, the facial expression recognition method provides robustness against partial occlusion, the classification accuracy only decreasing from 89.7% (no occlusion) to 84% (eyes region occlusion) and 83.5% (mouth region occlusion) for the first database and from 94.5% (no occlusion) to 91.5% (eyes region occlusion) and 87.2% (mouth region occlusion) for the second database, respectively.

Ioannis Pitas

Papers

Optimum nonlinear signal detection and estimation in the presence of ultrasonic speckle.

Image watermarking using block site selection and DCT domain constraints.

Fourier descriptors watermarking of vector graphics images

Morphological shape representation

Facial expression analysis under partial occlusion