Alexander Pacha

Dr. Alexander Pacha

Institute of Information Systems Engineering, TU Wien, 1040 Vienna, Austria
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Research Focus & Metrics

Academic Career Length

16Years (2011-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 July 2020 in ACM Computing Surveys
Verified
Journal Article
Open access
JCJorge Calvo-Zaragoza
Jorge Calvo-Zaragoza
JJJan Hajič Jr.
Jan Hajič Jr.
APAlexander Pacha
Alexander Pacha
For over 50 years, researchers have been trying to teach computers to read music notation, referred to as Optical Music Recognition (OMR). However, this field is still difficult to access for new researchers, especially those without a significant musical background: Few introductory materials are available, and, furthermore, the field has struggled with defining itself and building a shared terminology. In this work, we address these shortcomings by (1) providing a robust definition of OMR and its relationship to related fields, (2) analyzing how OMR inverts the music encoding process to recover the musical notation and the musical semantics from documents, and (3) proposing a taxonomy of OMR, with most notably a novel taxonomy of applications. Additionally, we discuss how deep learning affects modern OMR research, as opposed to the traditional pipeline. Based on this work, the reader should be able to attain a basic understanding of OMR: its objectives, its inherent structure, its relationship to other fields, the state of the art, and the research opportunities it affords.

29 August 2018 in Applied Sciences
Verified
Journal Article
Open access
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APAlexander Pacha
Alexander Pacha
NNN/A N/A
N/A N/A
JCJorge Calvo-Zaragoza
Jorge Calvo-Zaragoza
Deep learning is bringing breakthroughs to many computer vision subfields including Optical Music Recognition (OMR), which has seen a series of improvements to musical symbol detection achieved by using generic deep learning models. However, so far, each such proposal has been based on a specific dataset and different evaluation criteria, which made it difficult to quantify the new deep learning-based state-of-the-art and assess the relative merits of these detection models on music scores. In this paper, a baseline for general detection of musical symbols with deep learning is presented. We consider three datasets of heterogeneous typology but with the same annotation format, three neural models of different nature, and establish their performance in terms of a common evaluation standard. The experimental results confirm that the direct music object detection with deep learning is indeed promising, but at the same time illustrates some of the domain-specific shortcomings of the general detectors. A qualitative comparison then suggests avenues for OMR improvement, based both on properties of the detection model and how the datasets are defined. To the best of our knowledge, this is the first time that competing music object detection systems from the machine learning paradigm are directly compared to each other. We hope that this work will serve as a reference to measure the progress of future developments of OMR in music object detection.

1 April 2018
Verified
Conference Paper
Closed access
APAlexander Pacha
Alexander Pacha
KCKwon-Young Choi
Kwon-Young Choi
BCBertrand Couasnon
Bertrand Couasnon
YRYann Ricquebourg
Yann Ricquebourg
RZRichard Zanibbi
Richard Zanibbi
HEHorst Eidenberger
Horst Eidenberger
Optical Music Recognition (OMR) is the challenge of understanding the content of musical scores. Accurate detection of individual music objects is a critical step in processing musical documents because a failure at this stage corrupts any further processing. So far, all proposed methods were either limited to typeset music scores or were built to detect only a subset of the available classes of music symbols. In this work, we propose an end-to-end trainable object detector for music symbols that is capable of detecting almost the full vocabulary of modern music notation in handwritten music scores. By training deep convolutional neural networks on the recently released MUSCIMA++ dataset which has symbol-level annotations, we show that a machine learning approach can be used to accurately detect music objects with a mean average precision of over 80%.

1 November 2017
Verified
Conference Paper
Closed access
APAlexander Pacha
Alexander Pacha
HEHorst Eidenberger
Horst Eidenberger
Optical Music Recognition (OMR) aims to recognize and understand written music scores. With the help of Deep Learning, researchers were able to significantly improve the stateof- the-art in this research area. However, Deep Learning requires a substantial amount of annotated data for supervised training. Various datasets have been collected in the past, but without a common standard that defines data formats and terminology, combining them is a challenging task. In this paper we present our approach towards unifying multiple datasets into the largest currently available body of over 90000 musical symbols that belong to 79 classes, containing both handwritten and printed music symbols. A universal music symbol classifier, trained on such a dataset using Deep Learning, can achieve an accuracy that exceeds 98%.

1 December 2017
Verified
Conference Paper
Closed access
APAlexander Pacha
Alexander Pacha
HEHorst Eidenberger
Horst Eidenberger
Optical Music Recognition (OMR) is a branch of artificial intelligence that aims at automatically recognizing and understanding the content of music scores in images. Several approaches and systems have been proposed that try to solve this problem by using expert knowledge and specialized algorithms that tend to fail at generalization to a broader set of scores, imperfect image scans or data of different formatting. In this paper we propose a new approach to solve OMR by investigating how humans read music scores and by imitating that behavior with machine learning. To demonstrate the power of this approach, we conduct two experiments that teach a machine to distinguish entire music sheets from arbitrary content through frame-by-frame classification and distinguishing between 32 classes of handwritten music symbols which can be a basis for object detection. Both tasks can be performed at high rates of confidence (> 98%) which is comparable to the performance of humans on the same task.

1 September 2011
Verified
Conference Paper
Closed access
RMRichard Mordinyi
Richard Mordinyi
APAlexander Pacha
Alexander Pacha
SBStefan Biffl
Stefan Biffl
Participants in modern automation engineering projects typically work distributed and in parallel. Therefore, there are advanced approaches for integrating the data of specific engineering tools and systems. However, in these projects there are also participants who do not work with the specific engineering tool set but provide important data updates, e.g., customer representatives. A major challenge is to provide systematic and efficient quality assurance for these inputs. In this paper we describe an approach to provide efficient quality assurance when importing data from general purpose tools such as Excel into an integrated engineering data set. We report on experiences with initial prototypes and compare the improved with a traditional data import process to discuss advantages, risks, and further improvements.