Fuzzy Intervals for Designing Structural Signature: An Application to Graphic Symbol Recognition

Revised selected papers from Eighth IAPR International Workshop on Graphics RECognition (GREC) 2009.The motivation behind our work is to present a new methodology for symbol recognition. The proposed method employs a structural approach for representing visual associations in symbols and a statistical classifier for recognition. We vectorize a graphic symbol, encode its topological and geometrical information by an attributed relational graph and compute a signature from this structural graph. We have addressed the sensitivity of structural representations to noise, by using data adapted fuzzy intervals. The joint probability distribution of signatures is encoded by a Bayesian network, which serves as a mechanism for pruning irrelevant features and choosing a subset of interesting features from structural signatures of underlying symbol set. The Bayesian network is deployed in a supervised learning scenario for recognizing query symbols. The method has been evaluated for robustness against degradations & deformations on pre-segmented 2D linear architectural & electronic symbols from GREC databases, and for its recognition abilities on symbols with context noise i.e. cropped symbols

Learning Cross-Modal Deep Embeddings for Multi-Object Image Retrieval using Text and Sketch

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordIn this work we introduce a cross modal image retrieval system that allows both text and sketch as input modalities for the query. A cross-modal deep network architecture is formulated to jointly model the sketch and text input modalities as well as the the image output modality, learning a common embedding between text and images and between sketches and images. In addition, an attention model is used to selectively focus the attention on the different objects of the image, allowing for retrieval with multiple objects in the query. Experiments show that the proposed method performs the best in both single and multiple object image retrieval in standard datasets.European Union Horizon 2020CERCA Programme/Generalitat de Cataluny

Recognition of architectural and electrical symbols by COSFIRE filters with inhibition

The automatic recognition of symbols can be used to automatically convert scanned drawings into digital representations compatible with computer aided design software. We propose a novel approach to automatically recognize architectural and electrical symbols. The proposed method extends the existing trainable COSFIRE approach by adding an inhibition mechanism that is inspired by shape-selective TEO neurons in visual cortex. A COSFIRE filter with inhibition takes as input excitatory and inhibitory responses from line and edge detectors. The type (excitatory or inhibitory) and the spatial arrangement of low level features are determined in an automatic configuration step that analyzes two types of prototype pattern called positive and negative. Excitatory features are extracted from a positive pattern and inhibitory features are extracted from one or more negative patterns. In our experiments we use four subsets of images with different noise levels from the Graphics Recognition data set (GREC 2011) and demonstrate that the inhibition mechanism that we introduce improves the effectiveness of recognition substantially

Interpretation, Evaluation and the Semantic Gap ... What if we Were on a Side-Track?

International audienceA significant amount of research in Document Image Analysis, and Machine Perception in general, relies on the extraction and analysis of signal cues with the goal of interpreting them into higher level information. This paper gives an overview on how this interpretation process is usually considered, and how the research communities proceed in evaluating existing approaches and methods developed for realizing these processes. Evaluation being an essential part to measuring the quality of research and assessing the progress of the state-of-the art, our work aims at showing that classical evaluation methods are not necessarily well suited for interpretation problems, or, at least, that they introduce a strong bias, not necessarily visible at first sight, and that new ways of comparing methods and measuring performance are necessary. It also shows that the infamous {\em Semantic Gap} seems to be an inherent and unavoidable part of the general interpretation process, especially when considered within the framework of traditional evaluation. The use of Formal Concept Analysis is put forward to leverage these limitations into a new tool to the analysis and comparison of interpretation contexts

Report on the Symbol Recognition and Spotting Contest

LORIA / INPL- cole des Mines de Nanc

A Performance Characterization Algorithm for Symbol Localization

In this paper we present an algorithm for performance characterization of symbol localization systems. This algorithm aims to be more “generic ” and “fuzzy ” to characterize the performance. It exploits only single points as the results of localization and compare them with the groundtruth, using information about context. Probability scores are computed for each localization point, depending on the spatial distribution of the regions in the groundtruth. Final characterization results are given with a detection rates/probability error plot, describing the sets of possible interpretations of the localization results. We present experiments and results done with the symbol localization system of [1], using a synthetic dataset of floorplans (100 images, 2500 symbols). We conclude about the performance of this system, in terms of localization accuracy and precision level (false alarms and multiple detections)

Datasets for the Evaluation of Substitution-Tolerant Subgraph Isomorphism

International audienceDue to their representative power, structural de-scriptions have gained a great interest in the community working on graphics recognition. Indeed, graph based representations have successful been used for isolated symbol recognition. New challenges in this research field have focused on symbol recog-nition, symbol spotting or symbol based indexing of technical drawing. When they are based on structural descriptions, these tasks can be expressed by means of a subgraph isomorphism search. Indeed, in consists in locating the instance of a pattern graph representing a symbol in a target graph representing the whole document image. However, there is a lack of publicly available datasets allowing to evaluate the performance of subgraph iso-morphism approaches in presence of noisy data. In this paper, we present three datasets that can be used to evaluate the performance of algorithms on several tasks involving subgraph isomorphism. Two of these datasets have been synthetically generated and allow to evaluate the search of a single instance of the pattern with or without perturbed labels. The third dataset corresponds to the structural description of architectural plans and allows to evaluate the search of multiple occurrences of the pattern. These datasets are made available for download. We also propose several measures to qualify each of the tasks

Computing Precision and Recall with Missing or Uncertain Ground Truth

Abstract. In this paper we present a way to use precision and recall measures in total absence of ground truth. We develop a probabilistic interpretation of both measures and show that, provided a sufficient number of data sources are available, it offers a viable performance measure to compare methods if no ground truth is available. This paper also shows the limitations of the approach, in case a systematic bias is present in all compared methods, but shows that it maintains a very high level of overall coherence and stability. It opens broader perspectives and can be extended to handling partial or unreliable ground truth, as well as levels of prior confidence in the methods it aims to compare.