David Mas

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An automatic method for three-dimensional (3-D) shape recognition is proposed. It combines the Fourier transform profilometry technique with a real-time recognition setup such as the joint transform correlator (JTC). A grating is projected onto the object surface resulting in a distorted grating pattern. Since this pattern carries information about the(More)
Recent advances in ophthalmic anterior segment imaging: a new era for ophthalmic diagnosis? " , Brit. J Ophthalmol. 91, 551-557 (2007). [7] C. O'Donnell, C. Maldonado-Codina, " Agreement and repeatability of central thickness measurement in normal corneas using ultrasound pachymetry and the OCULUS pentacam " , Cornea 24, 920-924 (2005). ABSTRACT: The(More)
PURPOSE The aim of this study is to determine the reliability of corneal thickness measurements derived from SOCT Copernicus HR (Fourier domain OCT). METHODS Thirty healthy eyes of 30 subjects were evaluated. One eye of each patient was chosen randomly. Images were obtained of the central (up to 2.0 mm from the corneal apex) and paracentral (2.0 to 4.0(More)
PURPOSE To evaluate the changes in the optical quality of corneas of hyperopic patients operated using central multifocal presbyLASIK treatment through the study of light patterns around the retinal plane. METHODS This study included eight hyperopic eyes that underwent central presbyLASIK surgery with Presby-one software using an H. Eye Tech Technovision(More)
An optoelectronic implementation of the nonlinear morphological correlation by use of a threshold-decomposition technique and a joint transform correlator architecture is presented. This nonlinear morphological correlation provides improved image detection compared with standard linear optical pattern-recognition correlation methods. It also offers a more(More)
A method for the calculation of the fractional Fourier transform (FRT) by means of the fast Fourier transform (FFT) algorithm is presented. The process involves mainly two FFT's in cascade; thus the process has the same complexity as this algorithm. The method is valid for fractional orders varying from -1 to 1. Scaling factors for the FRT and Fresnel(More)
The expanding use of optical communication by means of optical fibers and the situation of drastically increasing amounts of data to be transmitted urge the exploration of novel systems permitting the transmission of large amounts of spatial information by fiber with smaller spatial resolution. An optical encoding and decoding system is suggested for(More)
The wavelet transform, which has had a growing importance in signal and image processing, has been generalized by association with both the wavelet transform and the fractional Fourier transform. Possible implementations of the new transformation are in image compression, image transmission, transient signal processing, etc. Computer simulations demonstrate(More)
We present a noninvasive technique for high-speed measuring of eye retraction and eyelid position during blinking. The anterior chamber of the eye is illuminated by the slit lamp of a biomicroscope and eye dynamics during a blinking sequence are captured with a high-speed camera working at 500 frames per second. Digital image processing allows quantitative(More)
Investing in radical innovation requires specific forms of investment , which have to deal with knightian uncertainty. This paper focuses on the links developed by venture capitalists between them, through co-investment operation, and studies their relationship through social network analysis. We analyze the influence of different proximities (essentially(More)