Handwriting Recognition Research Research Articles

Generative adversarial networks for handwriting image generation: a review

AbstractHandwriting synthesis, the task of automatically generating realistic images of handwritten text, has gained increasing attention in recent years, both as a challenge in itself, as well as a task that supports handwriting recognition research. The latter task is to synthesize large image datasets that can then be used to train deep learning models to recognize handwritten text without the need for human-provided annotations. While early attempts at developing handwriting generators yielded limited results [1], more recent works involving generative models of deep neural network architectures have been shown able to produce realistic imitations of human handwriting [2–19]. In this review, we focus on one of the most prevalent and successful architectures in the field of handwriting synthesis, the generative adversarial network (GAN). We describe the capabilities, architecture specifics, and performance of the GAN-based models that have been introduced to the literature since 2019 [2–14]. These models can generate random handwriting styles, imitate reference styles, and produce realistic images of arbitrary text that was not in the training lexicon. The generated images have been shown to contribute to improving handwriting recognition results when augmenting the training samples of recognition models with synthetic images. The synthetic images were often hard to expose as non-real, even by human examiners, but also could be implausible or style-limited. The review includes a discussion of the characteristics of the GAN architecture in comparison with other paradigms in the image-generation domain and highlights the remaining challenges for handwriting synthesis.

Burapha-TH: A Multi-Purpose Character, Digit, and Syllable Handwriting Dataset

In handwriting recognition research, a public image dataset is necessary to evaluate algorithm correctness and runtime performance. Unfortunately, in existing Thai language script image datasets, there is a lack of variety of standard handwriting types. This paper focuses on a new offline Thai handwriting image dataset named Burapha-TH. The dataset has 68 character classes, 10 digit classes, and 320 syllable classes. For constructing the dataset, 1072 Thai native speakers wrote on collection datasheets that were then digitized using a 300 dpi scanner. De-skewing, detection box and segmentation algorithms were applied to the raw scans for image extraction. The experiment used different deep convolutional models with the proposed dataset. The result shows that the VGG-13 model (with batch normalization) achieved accuracy rates of 95.00%, 98.29%, and 96.16% on character, digit, and syllable classes, respectively. The Burapha-TH dataset, unlike all other known Thai handwriting datasets, retains existing noise, the white background, and all artifacts generated by scanning. This comprehensive, raw, and more realistic dataset will be helpful for a variety of research purposes in the future.

An effective digit recognition model using enhanced convolutional neural network based chaotic grey wolf optimization

Classical Handwriting recognition systems depend on manual feature extraction with a lot of previous domain knowledge. It’s difficult to train an optical character recognition system based on these requirements. Deep learning approaches are at the centre of handwriting recognition research, which has yielded breakthrough results in recent years. However, the rapid growth in the amount of handwritten data combined with the availability of enormous processing power necessitates an increase in recognition accuracy and warrants further investigation. Convolutional Neural Networks (CNNs) are extremely good at perceiving the structure of handwritten characters in ways that allow for the automatic extraction of distinct features, making CNN the best method for solving handwriting recognition problems. In this research work, a novel CNN has built to modify the network structure with Orthogonal Learning Chaotic Grey Wolf Optimization (CNN-OLCGWO). This modification is adopted for evolutionarily optimizing the number of hyper-parameters. This proposed optimizer predicts the optimal values from the fitness computation and shows better efficiency when compared to various other conventional approaches. The ultimate target of this work is to endeavour a suitable path towards digitalization by offering superior accuracy and better computation. Here, MATLAB 2018b has been used as the simulation environment to measure metrics like accuracy, recall, precision, and F-measure. The proposed CNN- OLCGWO offers a superior trade-off in contrary to prevailing approaches.

Character context: a shape descriptor for Arabic handwriting recognition

In the handwriting recognition field, designing good descriptors are substantial to obtain rich information of the data. However, the handwriting recognition research of a good descriptor is still an open issue due to unlimited variation in human handwriting. We introduce a “character context descriptor” that efficiently dealt with the structural characteristics of Arabic handwritten characters. First, the character image is smoothed and normalized, then the character context descriptor of 32 feature bins is built based on the proposed “distance function.” Finally, a multilayer perceptron with regularization is used as a classifier. On experimentation with a handwritten Arabic characters database, the proposed method achieved a state-of-the-art performance with recognition rate equal to 98.93% and 99.06% for the 66 and 24 classes, respectively.

Hybrid Wavelet based Technique for Text Extraction from Images

This paper reviews the current state of the art in handwriting recognition research. The paper deals with issues such as hand-printed character and cursive handwritten word recognition. It describes recent achievements, difficulties, successes and challenges in all aspects of handwriting recognition.

Handwriting recognition research: Twenty years of achievement… and beyond

This panel discussion was a follow-up to the first edition of the ICFHR series, which was promoted as an international conference after 10 intensive and productive editions of the International Workshop on Frontiers in Handwriting Recognition initiated in 1990 in Montreal. It is essential, however, to recall that research on handwritten character recognition began some 40 years ago, and was expanded about 20 years ago to the more general notion of handwriting recognition (no longer constrained to isolated characters) that we work with today. The organizers of ICFHR 2008 wanted to take the opportunity to organize the panel discussion, chaired by M. Cheriet, to highlight progress in the field over the long course of its development. Panelists M. El Yacoubi, H. Fujisawa, D. Lopresti, and G. Lorette talked about the achievements of two decades of handwriting recognition and about its future. Following these outstanding presentations, conference attendees had the opportunity to air their questions and concerns during open and fruitful exchanges. Each section of this summary is drawn from the original presentation of a panelist. In Section 1, Dr. Hiromichi Fujisawa of Hitachi (Japan) discusses the impact of handwriting recognition technologies on the industrial sector. In Section 2, Dr. Mounim A. El Yacoubi of Institut Telecom, T&M SudParis (France) discusses the need to restructure the efforts of the handwriting recognition community. In Section 3, Dr. Guy Lorette of IRISA—Universite de Rennes (France) highlights the recent achievements in handwriting recognition and others on the horizon. In Section 4, Dr. Daniel Lopresti of Lehigh University (USA) discusses the future of handwriting recognition research as a “Grand Challenge” problem. Section 5 concludes this summary by highlighting the salient points that will drive research on handwriting recognition in the future.

Segmentation and Recognition of Handwritten Numeric Chains

Automatic reading of numeric chains has been attempted in several application areas such as bank cheque processing, postal code recognition and form processing. Such applications have been very popular in handwriting recognition research, due to the possibility to reduce considerably the manual effort involved in these tasks. In this study we propose an off line system for the recognition of the handwritten numeric chains. Firstly, study was based mainly on the evaluation of neural network performances, trained with the gradient back propagation algorithm. Used parameters to form the input vector of the neural network are extracted on the binary images of the digits by several methods: distribution sequence, Barr features and centred moments of different projections and profiles. Secondly, study was extented for the reading of the handwritten numeric chains constituted of a variable number of digits. Vertical projection was used to segment the numeric chain at isolated digits and every digit (or segment) was presented separately to the entry of the system achieved in the first part (recognition system of the isolated handwritten digits). The performances of the proposed system for the used database attain a recognition rate equal to 91.3%.

HANDWRITING RECOGNITION OF WHITEBOARD NOTES — STUDYING THE INFLUENCE OF TRAINING SET SIZE AND TYPE

This paper presents a system for the recognition of online whiteboard notes. Notes written on a whiteboard is a new modality in handwriting recognition research that has received relatively little attention in the past. For the recognition we use an offline HMM-recognizer, which is supplemented with methods for processing the online data and generating offline images. The system consists of six main modules: online preprocessing, transformation of online to offline data, offline preprocessing, feature extraction, classification and post-processing. The recognition rate of our basic recognizer in a writer independent experiment is 59.5%. By applying state-of-the-art methods, such as optimizing the number of states and Gaussian components, and by including a language model we could achieve a statistically significant increase of the recognition rate to 64.3%. To further improve the system performance we increased the size of the training set. For that we investigated two different strategies. First, we used another existing database of offline handwritten text. Second, we used a recently collected whiteboard database, called the IAM-OnDB. By means of these strategies the recognition rate could be further increased up to 68.5%.