Pen Pressure Research Articles

Examination of Simulated Forgery and its Investigation Protocol

Every day, we may face signature verification problem directly or indirectly whether it is in a banking transaction or signing a credit card transaction or authenticating a legal document. Signature identification and the questions of disguise, forgery and genuineness account for a significant proportion of a document examiner's case load. The development and examination, of a personal signature follows almost all of the concepts relating to handwriting. General indications of non-genuineness may include blunt starts and stops, pen lifts, hesitations, tremor, speed, pressure and patching. Forgery is an illegal modification or reproduction of an image, document signature, legal tender or any other means of recording information. Now-a-days, forgery detection is very important for real world events. In the present study 3 specimen of signature were collected from 50 individuals and were simulated for the examination of simulated forgery and its investigation protocol with Video Spectral Comparator.

Offline writer verification based on forensic expertise: Analyzing multiple characters by combining the shape and advanced pen pressure information

Offline writer verification based on forensic expertise: Analyzing multiple characters by combining the shape and advanced pen pressure information

Psychological and Physiological Processes in Figure-Tracing Abilities Measured Using a Tablet Computer: A Study with 7 and 9 Years Old Children.

The present study investigated the use of a tablet computer to assess figure-tracing skills and their relationships with psychological (visual–perceptual processes, cognitive processes, handwriting skills) and physiological (body mass index, isometric strength of arms) parameters with school-children of second (7–8-year-olds) and fourth (9–10-year-olds) grades. We were also interested in gender differences. The task required tracing of geometric figures on a template, shown on a tablet screen in light gray, for the segments that make up the target figure, one at a time. This figure-tracing tablet test allows acquisition and automated analysis of four parameters: number of strokes (pen lift) for each segment; oscillations of lines drawn with respect to reference lines; pressure of pen on tablet; and average speed of tracing. The results show a trade-off between speed and quality for the tablet parameters, with higher speed associated with more oscillations with respect to the reference lines, and lower number of strokes for each segment, in both male and female children. The involvement of visual–motor integration on the ability to reduce the oscillations in this tablet test was only seen for the male children, while both the male and female children showed a relationship between oscillations and more general/abstract visual–spatial processes. These data confirm the role of visual–motor processes in this figure-tracing tablet test only for male children, while more general visual–spatial processes influence the performance in the tablet test for both sexes. We conclude that the test proposed is useful to screen for grapho-motor difficulties.

Handwriting performance versus arm forward reach and grasp abilities among post-stroke patients, a case-control study

Background: Evidence-based studies regarding deficits in handwriting performance relative to hand reaching and grasping after a stroke are lacking.Objective: To evaluate the extent of damage to handwriting skills compared to arm reach and grasp task among post-stroke patients.Methods: Eighteen patients and 19 healthy subjects were recruited to this case-control study. Patients were evaluated 15.2 days (±6.5) after the stroke using a Computerized Penmanship Evaluation Tool, surface Electromyography and Fugl-Meyer assessment. This study compared motor deficits in hand reaching and grasping and in handwriting between stroke patients and healthy subjects. Damage to handwriting performance relative to hand reaching and grasping skills was also evaluated.Results: Significant differences were found between groups in handwriting performance (p < 0.05). The performance of the trapezius, biceps, and triceps muscles can predict 63.5% of the variance in the ability to write a short sentence (p < 0.023). Pen pressure can predict 74.9% of the hand motor performance from Fugl-Meyer assessment (p < 0.05). Handwriting was more damaged than was the pattern of activation of the proximal muscles of the shoulder and arm (p < 0.05). FM scores were highly, negatively correlated with the in-air writing time across tasks (r = −0.819, p < 0.004).Conclusions: This study confirms the clinical observation that dexterity skills are more damaged than are arm forward reach after a stroke. However, these differences in motor performance were not significant in mildly disabled patients, demonstrating the feasibility of handwriting rehabilitation in these patients. Therefore, we modestly recommend focusing on handwriting rehabilitation of the hemiparetic upper extremity in mildly impaired patients after a stroke.

Kinematic measures of brain drawings are associated with illness perceptions in people with stroke.

Previous research has shown that measuring the size and content of patients' drawings of their illness can reveal their perceptions and predict recovery. This study aimed to assess the usefulness of analyzing kinematic features of drawings. A pilot observational study was conducted with 15 patients who had been hospitalized with a stroke 8 to 11 months previously. They were asked to draw a picture of what they thought had happened to their brain and describe the drawing using an electronic inking pen and digitizing tablet. Analysis of kinematic data (time to draw/write, drawing/writing speed, and pen pressure) was conducted using MovAlyzeR® software. Evaluations of physical functioning, quality of life, illness perceptions, and emotional well-being were administered, and correlations with kinematic measures assessed. Stronger pen pressure was associated with perceptions of greater control over the stroke. Faster drawing was correlated with greater worry about a recurrent stroke and the perception that the effects of the stroke would last longer. Needing more time to write was associated with perceptions of fewer consequences of the stroke. No associations between kinematic measures and indicators of stroke severity, physical, or emotional well-being were shown. Kinematic measures of stroke patients' drawings of their brain and comments were associated with illness perceptions and not measures of physical or emotional health status. The addition of kinematic analysis may add further utility to the assessment of patients' drawings of their illness. More studies need to be performed with larger sample sizes and other patient groups.

A new algorithm for identity verification based on the analysis of a handwritten dynamic signature

Identity verification based on authenticity assessment of a handwritten signature is an important issue in biometrics. There are many effective methods for signature verification taking into account dynamics of a signing process. Methods based on partitioning take a very important place among them. In this paper we propose a new approach to signature partitioning. Its most important feature is the possibility of selecting and processing of hybrid partitions in order to increase a precision of the test signature analysis. Partitions are formed by a combination of vertical and horizontal sections of the signature. Vertical sections correspond to the initial, middle, and final time moments of the signing process. In turn, horizontal sections correspond to the signature areas associated with high and low pen velocity and high and low pen pressure on the surface of a graphics tablet. Our previous research on vertical and horizontal sections of the dynamic signature (created independently) led us to develop the algorithm presented in this paper. Selection of sections, among others, allows us to define the stability of the signing process in the partitions, promoting signature areas of greater stability (and vice versa). In the test of the proposed method two databases were used: public MCYT-100 and paid BioSecure.

The Influence of Lying Body Position on Handwriting.

Although the problem of handwriting variability due to lying body position has practical significance, particularly for last will cases, it has not been sufficiently studied. The presented experiment aimed to recognize how such posture may influence handwriting features. Samples of text and signatures were collected from 50 healthy individuals, aged 23-58, produced in three postures: typical sitting position (SP) and two different lying positions (LP1 & LP2). Using the SP sample of each individual as a specimen, eleven characteristics in LP1 and LP2 samples were evaluated as similar or different. Nine other features were measured with a specialized software, and their conformity was tested with Student's t-test. Although none of the characteristics differed significantly in most cases, variation occurred in pen pressure, margins, baselines, and heights of letters. Additionally, a series of blind tests revealed that lying position of the individuals did not hinder the possibility to identify their writings.

Comparação do desempenho motor de crianças com transtorno de aprendizagem e desenvolvimento típico

Durante a aprendizagem, encontra-se o período de aquisição das habilidades motoras, sendo este um aspecto relevante na vida do ser humano. No entanto, os estudos têm constatado várias dificuldades ocorridas durante o processo de escolarização, pois algumas crianças nesse período apresentam desempenho escolar abaixo do esperado para a idade. O presente estudo objetiva comparar o desempenho motor de crianças com transtorno de aprendizagem em relação às com desenvolvimento típico durante uma produção grafomotora. O desempenho motor fino foi avaliado por meio de produção grafomotora, sendo analisadas as variáveis: tempo de execução, tamanho absoluto, velocidade média, tremor, pressão da caneta, e quantidade de segmentos. Participaram do estudo 17 crianças com desenvolvimento típico e 17 com diagnóstico de transtorno de aprendizagem, do sexo masculino e feminino, com idade entre 10 e 13 anos.

"Let Me Hear Your Handwriting!" Evaluating the Movement Fluency from Its Sonification.

The quality of handwriting is evaluated from the visual inspection of its legibility and not from the movement that generates the trace. Although handwriting is achieved in silence, adding sounds to handwriting movement might help towards its perception, provided that these sounds are meaningful. This study evaluated the ability to judge handwriting quality from the auditory perception of the underlying sonified movement, without seeing the written trace. In a first experiment, samples of a word written by children with dysgraphia, proficient children writers, and proficient adult writers were collected with a graphic tablet. Then, the pen velocity, the fluency, and the axial pen pressure were sonified in order to create forty-five audio files. In a second experiment, these files were presented to 48 adult listeners who had to mark the underlying unseen handwriting. In order to evaluate the relevance of the sonification strategy, two experimental conditions were compared. In a first ‘implicit’ condition, the listeners made their judgment without any knowledge of the mapping between the sounds and the handwriting variables. In a second ‘explicit’ condition, they knew what the sonified variables corresponded to and the evaluation criteria. Results showed that, under the implicit condition, two thirds of the listeners marked the three groups of writers differently. In the explicit condition, all listeners marked the dysgraphic handwriting lower than that of the two other groups. In a third experiment, the scores given from the auditory evaluation were compared to the scores given by 16 other adults from the visual evaluation of the trace. Results revealed that auditory evaluation was more relevant than the visual evaluation for evaluating a dysgraphic handwriting. Handwriting sonification might therefore be a relevant tool allowing a therapist to complete the visual assessment of the written trace by an auditory control of the handwriting movement quality.

Local Features Analysis of On-Line Signature Using Modified Distance of DTW

Signature verification is a reliable and publicly acceptable method for authentication. Each signature is represented as a set of functional features such as coordinates of signature points, pen pressure and pen angle and therefore many features are available to the designer of signature verification system. The efficiency of any signature verification system depends mainly on the discrimination power and robustness of the features use in the system. This paper evaluates 40 dynamic features viewpoint classification error and consistency for extracting the best subset once a set of features provide maximal discrimination capability between genuine and forgery signatures. A modified distance of dynamic time warping (DTW) algorithm is proposed to improve performance of verification phase. The proposed system is evaluated on the public SVC2004 signature database. The experimental results show that first, the most discriminate and consistent features are velocity-based. Second, average equal error rate (EER) for proposed algorithm in comparison with the general DTW algorithm show a 47.5% decrease. Moreover, comparative study based on different classifier with skilled forgery show that the best result has EER of 1.73% using Parzen window classifier.

Text and User Generic Model for Writer Verification Using Combined Pen Pressure Information From Ink Intensity and Indented Writing on Paper

Writer verification is a method to specify an authentic writer from handwriting. Automated writer verification methods are required for various applications (e.g., credit cards, checks, and passports). However, there is room for improvement in the performance of such methods compared with the performance of human beings, for example, forensic document examiners. Because automated writer verification systems do not always return correct results under any circumstances, which can lead to grave consequences, further research is required to improve the performance of such methods. Furthermore, problems caused by limited samples must be solved for real applications. To improve verification accuracy with limited samples, we propose a text and user generic model for writer verification that uses a combination of pen pressure information from ink intensity and writing indentations obtained by a multiband image scanner. We introduce a writer-specific dissimilarity representation to consider individual handwriting characteristics that affect model performance. Experimental results obtained using handwriting samples collected from 54 volunteers are reported. The results show a decrease in error rate compared with conventional methods from 10.0% to 4.0%.

Anodal transcranial direct current stimulation to the cerebellum improves handwriting and cyclic drawing kinematics in focal hand dystonia.

There is increasing evidence that the cerebellum has a role in the pathophysiology of primary focal hand dystonia and might provide an intervention target for non-invasive brain stimulation to improve function of the affected hand. The primary objective of this study was to determine if cerebellar transcranial direct current stimulation (tDCS) improves handwriting and cyclic drawing kinematics in people with hand dystonia, by reducing cerebellar-brain inhibition (CBI) evoked by transcranial magnetic stimulation (TMS). Eight people with dystonia (5 writer’s dystonia, 3 musician’s dystonia) and eight age-matched controls completed the study and underwent cerebellar anodal, cathodal and sham tDCS in separate sessions. Dystonia severity was assessed using the Writer’s Cramp Rating Scale (WRCS) and the Arm Dystonia Disability Scale (ADDS). The kinematic measures that differentiated the groups were; mean stroke frequency during handwriting and fast cyclic drawing and average pen pressure during light cyclic drawing. TMS measures of cortical excitability were no different between people with FHD and controls. There was a moderate, negative relationship between TMS-evoked CBI at baseline and the WRCS in dystonia. Anodal cerebellar tDCS reduced handwriting mean stroke frequency and average pen pressure, and increased speed and reduced pen pressure during fast cyclic drawing. Kinematic measures were not associated with a decrease in CBI within an individual. In conclusion, cerebellar anodal tDCS appeared to improve kinematics of handwriting and circle drawing tasks; but the underlying neurophysiological mechanism remains uncertain. A study in a larger homogeneous population is needed to further investigate the possible therapeutic benefit of cerebellar tDCS in dystonia.

The Effect of a Visual Memory Training Program on Chinese Handwriting Performance of Primary School Students with Dyslexia in Hong Kong

This study investigated the effect of a visual memory training program on Chinese handwriting performance among primary school students with dyslexia in Hong Kong. Eight students of Grade 2 to 3 who were diagnosed with dyslexia were recruited. All participants received six sessions of training, which composed of 30-minute computerized game-based visual memory training and 30-minute Chinese character segmentation training. Visual perceptual skills and Chinese handwriting performance were assessed before and after the training, as well as three weeks after training using the Test of Visual Perceptual Skills (3rd edition) (TVPS-3) and the Chinese Handwriting Analysis System (CHAS). In comparing the pre- and post-training results, paired t-tests revealed significant improvements in visual memory skills, as well as handwriting speed, pause time and pen pressure after the training. There was no significant improvement in handwriting accuracy or legibility. The improved visual memory and handwriting performance did not show a significant drop at the follow-up assessments. This study showed promising results on a structured program to improve the Chinese handwriting performance, mainly in speed, of primary school children. The improvements appeared to be well-sustained after the training program. There is a need to further study the long-term effect of the program through a randomized controlled trial study.

Dynamic characteristics of signatures: effects of writer style on genuine and simulated signatures.

The aims of this study were to determine if computer-measured dynamic features (duration, size, velocity, jerk, and pen pressure) differ between genuine and simulated signatures. Sixty subjects (3 equal groups of 3 signature styles) each provided 10 naturally written (genuine) signatures. Each of these subjects then provided 15 simulations of each of three model signatures. The genuine (N = 600) and simulated (N = 2700) signatures were collected using a digitizing tablet. MovAlyzeR(®) software was used to estimate kinematic parameters for each pen stroke. Stroke duration, velocity, and pen pressure were found to discriminate between genuine and simulated signatures regardless of the simulator's own style of signature or the style of signature being simulated. However, there was a significant interaction between style and condition for size and jerk (a measure of smoothness). The results of this study, based on quantitative analysis and dynamic handwriting features, indicate that the style of the simulator's own signature and the style of signature being simulated can impact the characteristics of handwriting movements for simulations. Writer style characteristics might therefore need to be taken into consideration as potentially significant when evaluating signature features with a view to forming opinions regarding authenticity.

An off-line cheque handwritten forgery detection based on feature route density matrix

The security of handwritten documents is very important in authentication systems. In this paper, a forgery detection method is proposed for verifying handwritten documents. This method proposes two types of novel features: macro and micro. Macro features extract the structure of handwritten while micro features extract more detailed information. Also, the micro features try to extract some properties similar to online properties from offline data such as pen pressure and velocity. After extracting those features a PCA is applied to them which resulted in reducing the feature vector. A simple positive classifier is used separately to detect forgeries. It is very important that the weights of this classifier have been adjusted based on positive data because it is not possible to use forgery samples in adjusting phase. To test the proposed method a Persian handwritten data set was prepared using four kinds of forgeries; random, unskilled, skilled, and mimic. This data set consists of numbers written by text as reference words. The method performance using these different reference words showed the best result in correct rejection was 87 % while the correct acceptance was 97 %. We believe the proposed method can be applied to other languages by adjusting some parameters but because it is very important to have the data in high resolution format (e.g. 1,200 dpi) and none of databases have such resolution, the method was only applied to the dataset we gathered.

Kinematics of Signature Writing in Healthy Aging

Forensic document examiners (FDE) called upon to distinguish a genuine from a forged signature of an elderly person are often required to consider the question of age-related deterioration and whether the available exemplars reliably capture the natural effects of aging of the original writer. An understanding of the statistical relationship between advanced age and handwriting movements can reduce the uncertainty that may exist in an examiner's approach to questioned signatures formed by elderly writers. The primary purpose of this study was to systematically examine age-related changes in signature kinematics in healthy writers. Forty-two healthy subjects between the ages of 60-91 years participated in this study. Signatures were recorded using a digitizing tablet, and commercial software was used to examine the temporal and spatial stroke kinematics and pen pressure. Results indicated that vertical stroke duration and dysfluency increased with age, whereas vertical stroke amplitude and velocity decreased with age. Pen pressure decreased with age. We found that a linear model characterized the best-fit relationship between advanced age and handwriting movement parameters for signature formation. Male writers exhibited stronger age effects than female writers, especially for pen pressure and stroke dysfluency. The present study contributes to an understanding of how advanced age alters signature formation in otherwise healthy adults.

On-line signature verification using vertical signature partitioning

In this paper we propose a new approach to identity verification based on the analysis of the dynamic signature. Considered problem seems to be particularly important in terms of biometrics. Effectiveness of signature verification significantly increases when dynamic characteristics of the signature are considered (e.g. velocity, pen pressure, etc.). These characteristics are individual for each user and difficult to forge. The effectiveness of the verification on the basis of an analysis of the dynamics of the signature can be further improved. A well-known way is to consider the characteristics of the signature in the sections called partitions. In this paper we propose a new method for identity verification which uses partitioning. Partitions represent time moments of signing of the user. In the classification process the partitions, in which the user created more stable reference signatures during acquisition phase, are more important. Other important features of our method are: using capabilities of fuzzy set theory and development on the basis of them the flexible neuro-fuzzy systems and interpretable classification system for final signature classification. In this paper we have included the simulation results for the two currently available databases of dynamic signatures: free SVC2004 and commercial BioSecure database.

Discriminative Features Mining for Offline Handwritten Signature Verification

Signature verification is an active research area in the field of pattern recognition. It is employed to identify the particular person with the help of his/her signature’s characteristics such as pen pressure, loops shape, speed of writing and up down motion of pen, writing speed, pen pressure, shape of loops, etc. in order to identify that person. However, in the entire process, features extraction and selection stage is of prime importance. Since several signatures have similar strokes, characteristics and sizes. Accordingly, this paper presents combination of orientation of the skeleton and gravity centre point to extract accurate pattern features of signature data in offline signature verification system. Promising results have proved the success of the integration of the two methods.

Offline writer verification using pen pressure information from infrared image

Writer verification methods from handwriting images have been widely used in biometrics, forensic casework and so on. However, their performance conducted by a computer is still far behind that of human beings. This study proposes an offline writer verification method which uses a new hybrid feature. The characteristics of this new feature are the combination of shape and pen pressure information. For shape information, the authors use the weighted direction code histogram, which is often used in Japanese handwriting recognition and writer verification methods. For pen pressure information, the authors use the texture features of infrared (IR) images obtained from a multi-band image scanner. Although the simple use of pen pressure information encoded in the IR image cannot improve the geometric mean (g-mean)-based error rate, the use of clipping process and second-order statistics can decrease the g-mean-based error rate from 4.8 to 3.2%.

Research Progress of 3D Style Design Based on Sketching

This paper summarizes research progress of 3D style design based on sketching, especially focuses on 3D modeling method based on sketching, 3D stroke fitting. The future research direction on multi-strokes fitting and the use of digital pen pressure and other information for style design are proposed.