https://uvadoc.uva.es/handle/10324/27506 ECA-SIMM - Capítulos de Monografías Mon, 13 Apr 2026 19:17:37 GMT 2026-04-13T19:17:37Z https://uvadoc.uva.es/handle/10324/41029 A novel strategy for Automatic online Signature Verification based on hidden Markov models (HMM) with user-dependent structure is presented in this work. Under this approach, the number of states and Gaussians giving the optimal prediction results are independently selected for each user. With this simple strategy just three genuine signatures could be used for training, with an EER under 2.5% obtained for the basic set of raw signature parameters provided by the acquisition device. This results increment by a factor of six the accuracy obtained with the typical approach in which claim-independent structure is used for the HMMs. Mon, 01 Jan 2007 00:00:00 GMT https://uvadoc.uva.es/handle/10324/41029 2007-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/41028 In a previous work a new proposal for an efficient on-line signature recognition system with very low computational load and storage requirements was presented. This proposal is based on the use of size normalized signatures, which allows for similarity estimation, usually based on DTW or HMMs, to be performed by an easy distance calcultaion between vectors, which is computed using fractional distance. Here, a method to select representative features from the normalized signatures is presented. Only the most stable features in the training set are used for distance estimation. This supposes a larger reduction in system requirements, while the system performance is increased. The verification task has been carried out. The results achieved are about 30% and 20% better with skilled and random forgeries, respectively, than those achieved with a DTW-based system, with storage requirements between 15 and 142 times lesser and a processing speed between 274 and 926 times greater. The security of the system is also enhanced as only the representative features need to be stored, it being impossible to recover the original signature from these. Thu, 01 Jan 2009 00:00:00 GMT https://uvadoc.uva.es/handle/10324/41028 2009-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/41027 A new DTW-based on-line signature verification system is presented and evaluated. The system is specially designed to operate under realistic conditions, it needs only a small number of genuine signatures to operate and it can be deployed in almost any signature capable capture device. Optimal features sets have been obtained experimentally, in order to adapt the system to environments with different levels of security. The system has been evaluated using four on-line signature databases (MCYT, SVC2004, BIOMET and MyIDEA) and its performance is among the best systems reported in the state of the art. Average EERs over these databases lay between 0.41% and 2.16% for random and skilled forgeries respectively. Thu, 01 Jan 2009 00:00:00 GMT https://uvadoc.uva.es/handle/10324/41027 2009-01-01T00:00:00Z