Project SVAVISCA: a space-variant color CMOS sensor

Abstract

The paper describes the results of the first phase of the ESPRIT LTR project SVAVISCA. The aim of the project was to add color capabilities to a previously developed monochromatic version of a retina-like CMOS sensor. In such sensor, the photosites are arranged in concentric rings and with a size varying linearly with the distance from the geometric center. Two different technologies were investigated: 1) the use of Ferroelectric Liquid Crystal filters in front of the lens, 2) the deposition of color microfilters on the surface of the chip itself. The main conclusion is that the solution based on microdeposited filters is preferable in terms of both color quality and frame rate. The paper will describe in more detail the design procedures and the test results obtained.

Disparity Estimation on Log-Polar Images and Vergence Control

“…However, in the following experiments, only two df (i.e., the camera pans) were used to test the algorithm. The robotic setup is equipped with two spacevariant color cameras (20). Experiments were carried out on a standard Windows NT-based Pentium II 400-MHz machine.…”

“…Log-polar images, however, are ideal for vergence control tasks. They provide high resolution in the fovea, where the target should be located, and a wide field of view at the same time [20]. These features, along with a computationally simple mapping technique used for disparity estimation, allows real-time performance to be achieved with high accuracy.…”

“…It is assumed that η max = 2ξ max , as it is in the usual case (e.g., [20,26,32]), and that the Cartesian equivalent image is square. Besides, it is reasonable to assume that there would be no oversampling of pixels in the fovea and, thus, the following equations must hold: 27) where r f min is fixed and represents the diameter of the receptive field of minimum size in the fovea.…”

Learning to track colored objects with log-polar vision

“…From the sensory point of view, the robot is equipped with a pair of color spacevariant cameras [32,33], whose sensor's layout is analytically described in the next section, inertial sensors simulating the vestibular system [20,21], microphones for acoustic localization and proprioceptive information through motor encoders. The robot is controlled by a set of PCs--ranging from Pentium III to Pentium IV processors--each running Windows and connected by a fast Ethernet link (100 Mbit/s).…”

A retina-like CMOS sensor and its applications

“…The following technological step was to transform this CMOS sensor into a color one [11]. Two patterns for microfilters were tested ( see Figure 6).…”