RT info:eu-repo/semantics/article
T1 A methodology for contrast enhancement in laser speckle imaging : applications in Phaseolus vulgaris and Lactuca sativa seed bioactivity
A1 Herrera, Edher Zacarias
A1 Mello Román, Julio César
A1 Florentín Báez, Joel Miguelangel
A1 Palacios Bogarín, José Luis
A1 Mereles Menesse, Gustavo Eduardo
A1 Jara Ávalos, Jorge Antonio
A1 Franco, Marcos
A1 Méndez, Fernando José
A1 García Torres, Miguel
A1 Vázquez Noguera, José Luis
A1 Pérez Estigarribia, Pastor Enmanuel
A1 Grillo, Sebastián Alberto
A1 Legal Ayala, Horacio Andrés
A2 Universidad Americana/INCADE S.A.E
AB Laser Speckle Imaging (LSI) is a non-invasive optical technique used to assess biological activity by detecting dynamic variations in speckle patterns. These patterns exhibit statistical symmetry in static regions, while biological activity induces symmetry breaking that can be captured through the Graphic Absolute Value of Differences (GAVD), producing the activity map IGAVD. This work evaluates the effect of four contrast enhancement algorithms: Histogram Equalization (HE), Contrast Limited Adaptive Histogram Equalization (CLAHE), Multiscale Morphological Contrast Enhancement (MMCE), and Multiscale Top-Hat Transform with an Open-Close Close-Open (OCCO) filter, applied to intermediate LSI images, with the final activity map used for quantitative evaluation. Each method represents a distinct enhancement paradigm: HE and CLAHE are histogram-based techniques for global and local contrast adjustment, whereas MMCE and OCCO-MTH are morphological approaches that emphasize structural preservation and local detail enhancement. The dataset consisted of images of Phaseolus vulgaris (SP) and Lactuca sativa (SL) seeds. Evaluation was conducted through expert visual inspection and quantitative analysis using contrast, entropy, spatial frequency (SF), structural similarity index (SSIM), peak signal-to-noise ratio (PSNR), and contrast improvement ratio (CIR). All metrics were computed on IGAVD activity maps, which reflect bioactivity through the disruption of statistical symmetry. Non-parametric statistical tests (Friedman, aligned Friedman, and Quade) revealed that CLAHE and MMCE significantly improved image quality compared to the original images (p < 0.05). Among the evaluated algorithms, CLAHE increased global contrast by approximately 25% and entropy by 6% relative to the original speckle frames, enhancing the visibility of bioactive regions. MMCE achieved the highest bioactivity contrast ratio (CIR = 0.64), while OCCO-MTH provided the best structural fidelity (SSIM = 0.91) and noise suppression (PSNR = 30.7 dB). These results demonstrate that suitable contrast enhancement can substantially improve the interpretability of LSI activity maps without altering acquisition hardware. This finding is particularly relevant for experimental applications aiming to maximize information quality without modifying acquisition hardware.
PB Multidisciplinary Digital Publishing Institute
SN 2073-8994
YR 2025
FD 2025-11-27
LK http://hdl.handle.net/20.500.14066/4736
UL http://hdl.handle.net/20.500.14066/4736
LA eng
NO Herrera, E. Z., Mello-Román, J. C., Florentin, J., Palacios, J., Mereles Menesse, G. E., Jara Avalos, J. A., Franco, M., Méndez, F., García-Torres, M., Vázquez Noguera, J. L., Pérez-Estigarribia, P., Grillo, S., & Legal-Ayala, H. (2025). A Methodology for Contrast Enhancement in Laser Speckle Imaging: Applications in Phaseolus vulgaris and Lactuca sativa Seed Bioactivity. Symmetry, 17(12), Artículo 2029. https://doi.org/10.3390/sym17122029
NO Correspondence: julio.mello@ua.edu.py (J.C.M.-R.); jose.vazquez@ua.edu.py (J.L.V.N.).
NO This article belongs to the Special Issue Symmetry and Its Applications in Image Processing.
NO Consejo Nacional de Ciencia y Tecnología
DS MINDS@UW
RD 03-sep-2026