Ralph Niels

• PhD
• Professor (Associate) at HAN University of Applied Sciences

In this thesis, techniques and features are described that were developed for the automatic comparison of handwritten characters by first matching them to prototypical character shapes (allographs). These techniques and features were evaluated in experiments simulating different real-world applications. The majority of the experiments regard forens...

In this paper we discuss mixed-method research in HCI. We report on an empirical literature study of the NordiCHI 2012 proceedings which aimed to uncover and describe common mixed-method approaches, and to identify good practices for mixed-methods research in HCI. We present our results as mixed-method research design patterns, which can be used to...

A well-established task in forensic writer identification is the comparison of prototypical character shapes (allo-graphs) present in the handwriting. Using elastic match-ing techniques like Dynamic Time Warping (DTW), com-parison results can be made that are plausible and under-standable to the human expert. Since these techniques re-quire the dyn...

We show a number of promising results in writer identification, by recasting the traditional information re-trieval (IR) problem of finding documents based on the frequency of occurrence of their terms. In IR, the tf-idf is a well-known statistical measure that weighs the im-portance of certain terms occurring in a database of doc-uments. Here, wri...

The automatic extraction of handwriting styles is an important process that can be used for various applications in the processing of handwriting. We propose a novel method that employs hierarchical clustering to explore prominent clusters of handwriting. So-called membership vectors are introduced to describe the handwriting of a writer. Each memb...

During the execution of a flipped classroom course, chances increase students are not at the level scheduled in the initial planning with some students falling behind with their knowledge acquisition and others running ahead. In those cases, adding value during the in-class meetings is much harder for teachers, as they have to take care of all the...

This chapter addresses the challenge to determine what constitutes a contribution to HCI’s multidisciplinary research program. To improve the field’s understanding of contributions in HCI we have (1) outlined the changing narratives about contributions to HCI in the past 30 years, (2) performed an empirical literature study on a substantial set of...

The flipping classroom approach is directed at getting students well-prepared in class so that the valuable face-to-face time during the in-class meetings can be used more efficiently to support students' learning. This requires a radical change of the role of the lecturers, as they are not knowledge transmitters anymore but learning facilitators....

In this paper we discuss mixed-method research in HCI. We report on an empirical literature study of the NordiCHI 2012 proceedings which aimed to uncover and describe common mixed-method approaches, and to identify good practices for mixed-methods research in HCI. We present our results as mixed-method research design patterns, which can be used to...

Slant is a salient feature of Western handwriting and it is considered to be an important writer-specific feature. In disguised handwriting however, slant is often modified. It was tested whether slant is indeed an important factor and it was tested whether the distorting effect of deliberate slant change can be countered by a simple shear transfor...

Recent advances in interactive pen-aware systems, pattern recognition technologies, and human–computer interaction have provided new opportunities for pen-based communication between human users and intelligent computer systems. Using interactive maps, users can annotate pictorial or cartographic information by means of pen gestures and handwriting...

Many handwritten gestures, characters, and symbols comprise multiple pendown strokes separated by penup strokes. In this paper, a large number of features known from the literature are explored for the recognition of such multi-stroke gestures. Features are computed from a global gesture shape. From its constituent strokes, the mean and standard de...

The goal of this paper is to announce the NicIcon col-lection of handwritten sketches containing iconic gestures. These data have recently been collected in our group with the goal to develop and assess pen input recognition tech-nologies for the domain of crisis management. In our en-visaged scenarios, users can use the pen to enter, e.g., in-form...

Poor handwriting is a diagnostic criterion for developmental coordination disorder. Typical of poor handwriting is its low overall quality and the high variability of the spatial characteristics of the letters, usually assessed with a subjective handwriting scale. Recently, Dynamic Time Warping (DTW), a technique originally developed for speech rec...

A well-established task in forensic writer identification focuses on the comparison of prototypical character shapes (allographs) present in handwriting. In order for a computer to perform this task convincingly, it should yield results that are plausible and understandable to the human expert. Trajectory matching is a well-known method to compare...

Writer identication is an important issue in forensic investigations of handwritten documents. A particu- larly well-established method employed by forensic experts is to utilize distinctive features of handwritten characters for comparing pieces of handwriting. Our research within the NWO Trigraph project aims at automating this laborious process....

This paper discusses the use of Dynamic Time Warping (DTW) for visually perceptive and intuitive character recognition. In particular in forensic document examination, techniques are required that yield results matching a human user's expectations. In our approach, the goal is to retrieve a set of best matching allographic prototypes based on a que...

This paper describes the use of dynamic time warping (DTW) for classifying handwritten Tamil characters. Since DTW can match characters of arbitrary length, it is particularly suited for this domain. We built a prototype based classifier that uses DTW both for generating prototypes and for calculating a list of nearest prototypes. Prototypes were a...

This paper describes a semi-automated procedure for the verification of a large human-labeled data set containing online handwriting. A number of classifiers trained on the UNIPEN "trainset" is employed for detecting anomalies in the labels of the UNIPEN "devset". Multiple classifiers with different feature sets are used to increase the robustness...

With this presentation, we want to introduce the recently started TRIGRAPH project. The aim of this project is to de-velop techniques that can be used for forensic writer identifi-cation, using recent advances in pattern recognition and image processing, new insights in automatically derived handwriting features, user interface development, and inn...

Writer identification is an important issue in forensic investigations. In this paper, we propose a novel method for identifying a writer by means of features of loops and lead-in strokes of produced letters. Using a k-nearest-neighbor classifier, we were able to yield a correct identi-fication performance of 98% on a database of 41 writers. These...

Automatic handwriting recognition has had the interest of researchers for decades. Although there are various applications for which the technique is already used in daily life, a number of problems still has to be solved. At this moment, one of the biggest problems is the low user acceptance: the systems are not accurately enough, and moreover, th...