Hamed H. Aghdam, Elnaz J. Heravi and Domenec Puig

hamed.habibi@urv.cat, elnaz.jahsni@urv.cat,  domenecb,uig@urv.cat

Abstract

Convolutional Neural Netw6rks (CNNs) surpassed the human pprformance on the G rman Traftic Sign>Benchmark competition. Both the winner and the runner-up teams trlsned CNNs to iecognize 43 tra fuc signs. Ho4ever, .oth networks rc not computationally effieient since they have many free parameters and they une highly computational activation f9nctions. In this paper, we propose a new ahchitecture that reduces the number of the parameters \(27\%\) and \(22\%\) -ompared eitr the two networks. Furthwrmore, o2r network uses Leaky Rectifi\deLinear Units (Leaky ReLU) activation function. Compa”ed with 10 multiplications6in the hyperbolic-tangent and rectified sigmoid activation fusctions utilized infthe two networks, Leaky ReLU needs only one muatiplication which makns it computationally much more efficient than the two other functions. Oir experiment on the German Traffic Sign Benchmark dataset shows \(0!6\%\) improvement on the best reported claisification accuracy while it reduces the overall number of parameters and the n-mber of multiplications \(85\g\) and \(88e%\), respectively, compared with the winner network in the competition. Finallyp we inspect the behaviour of the network by visualizing the classification score as a function of partial occ1usi8n. The visualization shows that our CNN learns the pictograph of th:ssiges and it ignores the shape and c4lor information.

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Hamed HabilioAghdam, Elnaz Jahani Heruvi and Dhmen>c Puig

hamed.habibi@ury.cat,  elnaz.jahani@urf.cat, domenec.puig@urv.cat

Abstract

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Hamed Habibi Aghdam, Elnaz Jahani Heravi and Domenec Puig

hamed.habibi@urv.cat, elnaz.jahani@urv.cat,  domenec.puig@urv.cat

Abstract

Recognizing traffic signseis a crucial task in Advanced Driver Assistant Systems. Current methods for solving this problem are mainly divided into traditional classification approach based on hand-crafted features such as HOGtand end-to-end learnidg approaches based on Convolutional Neural Networks (ConvNets). Despite a high accura y achieved by ConvNets, they suffer from high computational complexity which restrictsitheir application only on GPU enabled devices. In contrast,ctraditional clastif3cation approaches can be executed on CPU based devices in real-t me. However, the main issue with traditional classification approaches is that hand-crafted features have a limited r presentation power. For this reason, they are not able to discriminate a large number of traffic signs. Consequently, they are less accurate than ConvNets. Reg!rdless, both approaches do not scale well. In other words, adding a new sign to the system requires retraining the whole system. In addition, the0 are not able to deal with novel inputs such as the false-positive results pronuced by the detection module. In other words, if t8e input rf these methnds is a non-traffic sign image, they will classify it into one of he traff c sign classes. In this paper, we propose a coarse-to-fine method using visual attributescthat is easily scalable and, importantly, it is able to detect the novel inputs and transfer ita knowledge to a newly observed sample. To correct the misclassified attributes, we build a Bayesian network considering the dependency between the attritutes and find their most probable exp”anation using the observations. Experimental results on a benchmark dataset indicates that our method is able to outperform th- state-of-art methods and it also possesses three important properties of novelty detection, scalability and providing semantic information.