Optics theory and practice in Iberoamerica: introduction to the feature issue.

This feature issue of Applied Optics (AO) on Optics Theory and Practice in Iberoamerica (OTPI) collects significantly expanded refereed papers presented at the multiconference RIAO-OPTILAS-MOPM, held in Cancún, Mexico, Sept. 23-27, 2019. All authors who participated at the conference were contacted and invited to contribute to this special issue.

Image correlation by one-dimensional signatures invariant to rotation, position, and scale using the radial Hilbert transform optimized.

This paper presents a new methodology for pattern recognition invariant to rotation, position, and scale. The method uses the correlation of signatures, where the signatures were created with a new equation called the radial Hilbert transform optimized (RHTO) for longer signatures. An analysis with eight non-homogeneous illumination patterns was performed with 2000 letter variants and 30 phytoplankton species.

Spectral indexes obtained by implementation of the fractional Fourier and Hermite transform for the diagnosis of malignant melanoma.

Many people suffer from different skin diseases, which can be diverse and varied. Most skin diseases cause disorders in the skin, such as changes in color, texture, and appearance manifesting in spots, swelling, scaling, ulcers, etc. One of the diseases that represents a serious health problem is skin cancer.

Identification of melanoma cells: a method based in mean variance of signatures via spectral densities.

In this paper a new methodology to detect and differentiate melanoma cells from normal cells through 1D-signatures averaged variances calculated with a binary mask is presented. The sample images were obtained from histological sections of mice melanoma tumor of 4 [Formula: see text] in thickness and contrasted with normal cells. The results show that melanoma cells present a well-defined range of averaged variances values obtained from the signatures in the four conditions used.

Methodology for diagnosing of skin cancer on images of dermatologic spots by spectral analysis.

In this paper a new methodology for the diagnosing of skin cancer on images of dermatologic spots using image processing is presented. Currently skin cancer is one of the most frequent diseases in humans. This methodology is based on Fourier spectral analysis by using filters such as the classic, inverse and k-law nonlinear.

Relationship between DAPI-fluorescence fading and nuclear DNA content: An alternative method to DNA quantification?

In observations by confocal or conventional fluorescence microscopy, important factors should be considered in order to obtain accurate images. One of them, such as the fluorescence bleaching from highest intensity to lowest signal of fluorescence is a common problem with several DNA fluorochromes and especially for DAPI stain. The fluorescence of DAPI fades rapidly when it is exposed to UV light, under optimal conditions of observation.

Fluorescence in situ hybridization of rDNA, telomeric (TTAGGG)n and (GATA)n repeats in the red abalone Haliotis rufescens (Archaeogastropoda: Haliotidae).

The physical location of 18S-5.8S-28S rDNA, telomeric sequences with (TTAGGG)n DNA probe and (GATA)n microsatellites were performed by fluorescence in situ hybridization in chromosomes of red abalone Haliotis rufescens. The karyotype of red abalone showed a diploid number of 36 (8M+9SM+1ST).

Pattern recognition with an adaptive joint transform correlator.

An adaptive joint transform correlator for real-time pattern recognition is presented. A reference image for the correlator is generated with a new iterative algorithm. The training algorithm is based on synthetic discriminant functions.