An Experimental-Based Review of Image Enhancement and Image Restoration Methods for Underwater Imaging

Underwater images play a key role in ocean exploration, but often suffer from severe quality degradation due to light absorption and scattering in water medium. Although major breakthroughs have been made recently in the general area of image enhancement and restoration, the applicability of new methods for improving the quality of underwater images has not specifically been captured. In this paper, we review the image enhancement and restoration methods that tackle typical underwater image impairments, including some extreme degradations and distortions. Firstly, we introduce the key causes of quality reduction in underwater images, in terms of the underwater image formation model (IFM). Then, we review underwater restoration methods, considering both the IFM-free and the IFM-based approaches. Next, we present an experimental-based comparative evaluation of state-of-the-art IFM-free and IFM-based methods, considering also the prior-based parameter estimation algorithms of the IFM-based methods, using both subjective and objective analysis (the used code is freely available at https://github.com/wangyanckxx/Single-Underwater-Image-Enhancement-and-Color-Restoration). Starting from this study, we pinpoint the key shortcomings of existing methods, drawing recommendations for future research in this area. Our review of underwater image enhancement and restoration provides researchers with the necessary background to appreciate challenges and opportunities in this important field

Aprovechamiento de lanche, hierbaluisa y stevia en la elaboración de infusiones

Many diseases such as cancer, diabetes, cholesterol, among others, need to be prevented and/or controlled, therefore, plants and herbs are an alternative due to their bioactive compounds. The objective was to take advantage of lemon verbena, lanche and stevia produced in the province of Chota for the formulation of infusions. The leaves were washed, disinfected, dried at 50 °C and ground; 40 treatments were carried out consisting of ten formulations with lemon verbena, lanche and stevia (85:0:15; 80:5:15; 70:15:15; 60:25:15; 50:35:15; 40:45:15; 30:55:15; 20:65:15; 10:75:15 and 0:85:15), with four infusion times (244, 265, 300 and 344 s.), pH, total soluble solids and color (L*, a* and b*). Four treatments with the best physicochemical properties were selected and sensory evaluations of the odor, color, flavor and sweetness attributes were carried out with 80 non-disruptive panelists. An association (R2 = 0.72) was found between infusion time and total soluble solids, percentage of lemon verbena and parameter b* (R2 = 0.77), percentage of lanche and parameter b* (R2 = -0.77); treatment T7 (30% lemon verbena, 55% lanché and 15% stevia, infusion time 244 s.) had the highest sensory acceptability in the attributes of smell, color, flavor and sweetness.Muchas enfermedades como el cáncer, la diabetes, el colesterol, entre otras; requieren ser prevenidas y/o controladas, por ello, las plantas y hierbas son una alternativa debido a sus compuestos bioactivos. El objetivo fue aprovechar la hierbaluisa, lanche y stevia producida en la provincia de Chota para la formulación de infusiones. Las hojas fueron lavadas, desinfectadas, secadas a 50 °C y molidas; se realizaron 40 tratamientos, consistente en diez formulaciones con hierbaluisa, lanche y stevia (85:0:15; 80:5:15; 70:15:15; 60:25:15; 50:35:15; 40:45:15; 30:55:15; 20:65:15; 10:75:15 y 0:85:15), con cuatro tiempos de infusión (244, 265, 300 y 344 s.), se evaluó pH, sólidos solubles totales y color (L*, a* y b*). Se seleccionó cuatro tratamientos con mejores propiedades fisicoquímicas para realizar la evaluación sensorial de los atributos de olor, color, sabor y dulzor con 80 panelistas no entrenados. Se encontró asociación (R2 = 0,72) entre tiempo de infusión y sólidos solubles totales, porcentaje de hierbaluisa y parámetro b* (R2 = 0,77). El tratamiento T7 (30% de hierbaluisa, 55% de lanché y 15% de stevia, tiempo de infusión 244 s.) tuvo la mayor aceptabilidad sensorial en los atributos de olor, color, sabor y dulzor