Showing papers by "José A. Ferrari published in 2012"
TL;DR: A fringe generation technique that consists of projecting and acquiring a temporal sequence of strictly binary color patterns, whose (adequately weighted) average leads to sinusoidal fringe patterns with the required number of bits, which allows for a reliable three-dimensional profile using a PSI-algorithm.
Abstract: Three-dimensional profiling by sinusoidal fringe projection using PSI-algorithms are distorted by the nonlinear response of digital cameras and commercial video projectors. To solve the problem, we present a fringe generation technique that consists of projecting and acquiring a temporal sequence of strictly binary color patterns, whose (adequately weighted) average leads to sinusoidal fringe patterns with the required number of bits, which allows for a reliable three-dimensional profile using a PSI-algorithm. Validation experiments are presented.
21 citations
TL;DR: A 3-D shape profiling method that involves the projection of two shifted strictly binary fringe patterns, whose adequately weighted average allows to synthesize a sawtooth pattern that overcomes the nonlinear response of digital cameras and commercial video projectors without previous calibration.
Abstract: We present a three-dimensional (3-D) shape profiling method that involves the projection of two shifted strictly binary (square wave) fringe patterns, whose adequately weighted average allows to synthesize a sawtooth pattern. We demonstrate that the deformed fringes (after unwrapping) provide an intensity pattern proportional to the depth profile of the surface. The proposed technique overcomes the nonlinear response (i.e., the "gamma problem") of digital cameras and commercial video projectors without previous calibration. The two binary patterns can be encoded in the color components of a single color image, which allows a reliable 3-D profiling surface reconstruction at large time-rates. Validation experiments are presented.
8 citations
TL;DR: A method for orientation-selective enhancement of edges in color images is proposed that utilizes the capacity of digital micromirror devices to generate a positive and a negative color replica of the image used as input.
Abstract: A method for orientation-selective enhancement of edges in color images is proposed. The method utilizes the capacity of digital micromirror devices to generate a positive and a negative color replica of the image used as input. When both images are slightly displaced and imagined together, one obtains an image with enhanced edges. The proposed technique does not require a coherent light source or precise alignment. The proposed method could be potentially useful for processing large image sequences in real time. Validation experiments are presented.
3 citations
TL;DR: In this article, an auto programmable spatial-filtering system using photochromic glass plate as a programmable SLM, illuminated by a single wavelength of light, is described.
2 citations
TL;DR: Unlike Fourier, the proposal works with incoherent illumination and does not require precise alignment, and thus, it could be a useful tool for edge extraction/enhancement in large images in real-time applications.
Abstract: We present optical methods for edge enhancement in color images using optical derivative operations (first order
derivative and Laplacian operator) The proposed methods is based on the polarization properties of liquid-crystal
displays (LCD) and on the capacity of digital micro mirror devices to generate a (positive) copy of the digital image used
as input, and simultaneously a complementary color replica of it In the proposed optical setup the negative and positive
replicas are at the same time imagined across a plane First we analyzed the case when the negative replica has a lateral
differential displacement relative to the original one; an image with enhanced first derivatives along a specific direction
is obtained In the case when the negative replica is low-pass filtered, one obtains the Laplacian of the original image
Unlike Fourier, our proposal works with incoherent illumination and does not require precise alignment, and thus, it
could be a useful tool for edge extraction/enhancement in large images in real-time applications Validation experiments
are presented