We use nonlinear composite filters in object recognition, even when they have rotation, scale, noise, and illumination distortions. We generated 936 images of the letters E, F, H, P, and B. The images consisted of these letters scaled from 70% to 130% and rotated 360 deg. The maximum number of images supported by these filters was determined by a numerical experiment. Considering a system confidence level of at least 80%, the maximum number of images is around 216. We found a "rotation problem" when the filter contained the letter rotated 360 deg, since circles were artificially introduced, and this creates complications when working with images that also have circles in their spectrum. Due to this, we propose a segmented filter that breaks the circular symmetry. Experiments where carried out in order to find the noise tolerance of each filter, and the use of Spearman's rank correlation (in conjunction with the nonlinear method, SNM) is proposed in order to increase that tolerance. We also made an assessment of the impact that illumination changes had in the correlation output, in the problem image, and we propose the use of SNM to obtain illumination invariance. We tested these filters with two real-life problems; nonlinear composite filters can recognize the target in the presence of distortions.
In this work we use non linear composite filters in object recognition, even when they have rotation, scale and noise
distortions. We generated 936 images of the letters E, F, H, P and B. The images consisted of these letters scaled from 70% to 130% and rotated 360°. The maximum number of images supported by these filters was determined by a numerical experiment. This was done by generating filters with different amount of images each. We have images at 13
scales and each scale with 72 different angles, tests were done to two different kinds of filters, one where all the scales were present and we add more angles to increase the number of images, and another where all of the angles were present and more scales were added to increase the number of images. Considering a system confidence level of at least 80%, the maximum number of images allowed by the filter is around 216. In one type of filter we have the letter rotated 360°. We found a "rotation problem", since circles were introduced in the Fourier plane, in other words first order Bessel functions were introduced in the image spectrum, which creates complications when working with images that also have circles in their spectrum. Due to this we propose a segmented filter which breaks the circular symmetry. Non-linear composite filters can recognize the target in presence of distortions.
Microbial mats are an extant paradigm of the earliest ecosystems. Defining the minimal ecosystem requirements necessary for the survival and proliferation of organisms is crucial in the search for extraterrestrial life and for establishing Earth-like ecosystems beyond our planet. Microbial mats are multilayered biofilms that operate as almost closed systems with persistent oxidation-reduction gradients and restricted vertical flows. Under the driving force of light the components interact and feedback flows become established. The community is the highest biological unit in an ecological hierarchy. The knowledge of the community composition is essential to understand the microbial mats dynamics. Understanding the factors that determine ecosystem stability has been one of the main challenges for ecologists. It has been pointed that both major and minor populations are important for maintaining ecosystem stability. Spirochetes represent one of the minor heterotrophic groups (ca. 1% total population) in microbial mats. However, when samples were examined with primers specific for the spirochete group, highly diverse collections of spirochete 16S rDNA were uncovered. Spirochetes may constitute a ubiquitous component of microbial mats that are linked to other microbial communities by robust trophic interactions.
Conference Committee Involvement (2)
Instruments, Methods, and Missions for Astrobiology IX
14 August 2006 | San Diego, California, United States
Instruments, Methods, and Missions for Astrobiology IX
31 July 2005 | San Diego, California, United States
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.