The impact of prenatal mercury on neurobehavioral functioning longitudinally assessed from a young age to pre-adolescence in a Spanish birth cohort.

The objective is to investigate the relation between cord blood mercury concentrations and child neurobehavioural functioning assessed longitudinally during childhood until pre-adolescence. METHODS: The study involves mothers and their offspring engaged in the Spanish INMA birth cohort (n = 1147). Total mercury (THg) was determined in cord blood. Behavioural problems were assessed several times during childhood using the ADHD-DSM-IV at age 4, SDQ at ages 7 and 11, CPRS-R:S and the CBCL at ages 7, 9 and 11. Covariates were obtained through questionnaires during the whole period. Multivariate generalised negative binomial (MGNB) models or mixed-effects MGNB (for those tests with information at one or more time points, respectively) were used to investigate the relation between cord blood THg and the children's punctuations. Models were adjusted for prenatal fish intake. Effect modification by sex, prenatal and postnatal fish intake, prenatal fruit and vegetable intake, and maternal polychlorinated biphenyl concentrations (PCBs) was assessed by interaction terms. RESULTS: The geometric mean ± standard deviation of cord blood THg was 8.22 ± 2.19 µg/L. Despite adjusting for fish consumption, our results did not show any statistically significant relationship between prenatal Hg and the children's performance on behavioural tests conducted between the ages of 4 and 11. Upon assessing the impact of various factors, we observed no statistically significant interaction. CONCLUSION: Despite elevated prenatal THg exposure, no association was found with children's behavioural functioning assessed from early childhood to pre-adolescence. The nutrients in fish could offset the potential neurotoxic impact of Hg. Further birth cohort studies with longitudinal data are warranted.

Pro-vegetarian dietary patterns and essential and heavy metal exposure in children of 4-5-years from the INfancia y medio Ambiente cohort (INMA).

Dietary patterns provide a comprehensive assessment of food consumption, including essential nutrients and potential exposure to environmental contaminants. While pro-vegetarian (PVG) dietary patterns have shown health benefits in adults, their effects on children are less well studied. This study aims to explore the association between children's adherence to the most common PVG dietary patterns and their exposure to metals, assessed through urine concentration. In our study, we included a population of 723 children aged 4-5-years from the INfancia y Medio Ambiente (INMA) cohort in Spain. We calculated three predefined PVG dietary patterns, namely general (gPVG), healthful (hPVG), and unhealthful (uPVG), using dietary information collected through a validated Food Frequency Questionnaire. Urinary concentrations of various essential and heavy metals (Co, Cu, Zn, Se, Mo, Pb, and Cd) were measured using mass spectrometry. Additionally, urinary arsenic speciation, including arsenobetaine (AsB), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), and inorganic arsenic (iAs), was measured. The sum of urinary MMA and iAs was used to assess iAs exposure. We estimated primary (PMI) and secondary iAs methylation (SMI) indices. To explore the association between PVG dietary patterns in quintiles and metal exposure, we utilized multiple-adjusted linear regression models and the quantile g-computation approach. Compared with the lowest quintile, participants in the highest quintile of gPVG showed a 22.7% lower urinary Co (95% confidence interval (CI): -38.7; -1.98) and a 12.6% lower Se (95%CI: -22.9; -1.00) concentrations. Second quintile of adherence to hPVG was associated with a 51.7% lower urinary iAs + MMA concentrations (95%CI: -74.3; -8.61). Second quintile of adherence to an uPVG was associated with a 13.6% lower Se levels (95%CI: -22.9; -2.95) while the third quintile to this pattern was associated with 17.5% lower Mo concentrations (95%CI: -29.5; -2.95). The fourth quintile of adherence to gPVG was associated with a 68.5% higher PMI and a 53.7% lower SMI. Our study showed that adherence to a gPVG dietary pattern in childhood may modestly reduce the intakes of some essential metals such as Co and Se. Further investigations are warranted to explore any potential health implications.

The association between intimate partner violence type and mental health in migrant women living in Spain: findings from a cross-sectional study.

Introduction: The association between intimate partner violence (IPV) and mental health has been clearly established in the literature, however the differential associations between IPV type and mental health are less well understood, particularly in migrant groups who are at increased risk of both IPV and poor mental health. Under-studied and emerging forms of violence such as economic abuse and technology-facilitated abuse must be considered alongside more traditionally studied forms of IPV in order to fully understand the complex nature of violence. This study makes a novel contribution to the literature by assessing multiple forms of IPV including psychological, physical, sexual, economic and technology-facilitated IPV and their relationship with symptoms of depression and anxiety in migrant women, disaggregated by IPV type. Methods: A cross-sectional survey of migrant women living in the Valencian Community of Spain was conducted, to assess experiences of IPV and symptoms of mental health. Regression analysis from the Bayesian perspective was performed. Results: 1,998 women accessed the survey. They had an average age of 37, and came predominantly from Europe (49%), namely Western Europe, followed by Latin America (38%). The majority had been in Spain between 1 and 3 years, and 80% had resident status. A total of 1,156 responded to questions on violence and mental health. Results showed that the prevalence of IPV was high, with 59% of women reporting any experience of violence. Economic abuse was the most commonly reported form of violence, and showed the strongest relationship with symptoms of depression. Sexual violence was the strongest predictor of anxiety. In both cases, in the presence of violence, the odds of having more severe symptoms of depression and anxiety increases by over 2.25. Technology-facilitated abuse was as detrimental to women's mental health as face-to-face violence. Discussion: The findings from the study are relevant to researchers, policy-makers and service providers. They highlight the complex nature of IPV experiences faced by migrant women and the importance of understanding how different types of IPV can impact migrant mental health, in order to ensure survivors receive adequate care.

[Niveles de mercurio en pescado en la Comunitat Valenciana: evolución temporal (2011-2017) y factores asociados.] / Mercury levels in fish in the Valencian Community: temporal evolution (2011-2017) and associated factors.

OBJECTIVE: Mercury (Hg) is a toxic metal, and dietary exposure is the main one in humans, especially fish consumption. In order to reduce Hg exposure, maximum levels in fish products have been established. We aimed to describe total mercury (THg) and methylmercury (MeHg) concentrations in fish species consumed in Comunitat Valenciana, as well as factors associated and their tendency during the period 2011-2017. METHODS: A retrospective descriptive study of Hg levels in fish meat samples in Comunitat Valenciana between 2011 and 2017 and their temporal trend was carried out, both in general and by fish groups. Data comes from Generalitat Valenciana's Health Surveillance of Food Program. We created multivariate linear regression models to evaluate the association between sampling year, fish group and origin and THg (n=560) / MeHg (n=206) concentrations. The average annual trend of THg and MeHg levels throughout the period was evaluated. RESULTS: The median was 0.20 mg/kg for THg and 0.14 mg/kg for MeHg. Swordfish, fresh tuna/albacore and canned tuna, in that order, showed the highest concentrations. Global tendency of THg levels was descending when adjusting by swordfish annual percentage. When we analized the tendency in swordfish, we observed a 7% decrease on average per year. CONCLUSIONS: Global temporal trend of THg levels in fish in Comunitat Valenciana during the period 2011-2017 is descending after adjusting by the relative weight of swordfish over the total number of samples by year. We observe a descending tendency when studied by species (swordfish).

OBJETIVO: El mercurio (Hg) es un metal tóxico cuya principal fuente de exposición en humanos es la dieta, principalmente el consumo de pescado. Para reducir la exposición al Hg se han establecido unos niveles máximos permitidos en productos de pesca. El objetivo del presente trabajo fue describir las concentraciones de mercurio total (THg) y metilmercurio (MeHg) en las especies de pescado dispuestas para el consumo en la Comunitat Valenciana, así como los factores asociados a dichas concentraciones y su evolución en el período 2011-2017. METODOS: Se realizó un estudio descriptivo, retrospectivo, de los niveles de Hg en muestras de pescado y de su evolución temporal, tanto en general como por grupos de pescado. Los datos proceden del Programa de Vigilancia Sanitaria de Alimentos de la Generalitat Valenciana. Se construyeron modelos de regresión lineal multivariantes para evaluar la asociación del año de muestreo, el grupo de pescado y el origen del mismo con las concentraciones de THg (n=560) y MeHg (n=206). Se evaluó la tendencia anual media de los niveles de THg y MeHg a lo largo del período. RESULTADOS: La mediana para THg fue de 0,20 mg/kg, y de 0,14 mg/kg para MeHg. El pez espada/emperador fue el grupo de pescado que presentó niveles más altos, seguido del atún/bonito frescos y del atún en lata. La tendencia global de los niveles de THg fue descendente ajustando por el peso anual de las muestras de pez espada/emperador. Al analizar la tendencia en pez espada/emperador se observó una disminución del 7% en promedio por año. CONCLUSIONES: La evolución temporal de los niveles de THg en pescado en la Comunitat Valenciana en el período 2011-2017 presenta una tendencia global descendente cuando se ajusta por el peso relativo de pez/espada emperador sobre el total de muestras para cada año. Además, al estudiar los niveles de THg en este grupo se observa una tendencia decreciente.

Genetic Susceptibility to Neurotoxicity Related to Prenatal Inorganic Arsenic Exposure in Young Spanish Children.

We explored the influence of child and maternal single nucleotide polymorphisms (SNPs) in genes related to neurological function and arsenic metabolism (i.e., ABCA1, ABCB1, PON1, CYP3A, BDNF, GSTP1, MT2A, and APOE as well as AS3MT) on the association between prenatal arsenic (As) exposure and methylation efficiency and neuropsychological development in 4-5-year-old children. Participants were 549 mother-child pairs from the INMA (Environment and Childhood) Spanish Project. We measured inorganic arsenic (iAs) and the metabolites monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in urine samples collected during pregnancy. Neuropsychological development was assessed at the age of 4-5 years using the McCarthy Scales of Children's Abilities (MSCA). Several SNPs were determined in maternal and child DNA; AS3MT and APOE haplotypes were inferred. The median ∑As (sum of iAs, DMA, and MMA) was 7.08 µg/g creatinine. Statistically significant interactions for children's APOE haplotype were observed. Specifically, ε4-carrier children had consistently lower MSCA scores in several scales with increasing ∑As and MMA concentrations. These results provide evidence regarding the neurotoxic effects of early life exposure to As, observing that the APOE ε4 allele could make children more vulnerable to this exposure.

Niveles de mercurio en pescado en la Comunitat Valenciana: evolución temporal (2011-2017) y factores asociados / Mercury levels in fish in the Valencian Community: temporal evolution (2011-2017) and associated factors

Fundamentos: El mercurio (Hg) es un metal tóxico cuya principal fuente de exposición en humanos es la dieta, principalmenteel consumo de pescado. Para reducir la exposición al Hg se han establecido unos niveles máximos permitidos en productos de pesca. El objetivo del presente trabajo fue describir las concentraciones de mercurio total (THg) y metilmercurio (MeHg) en las especiesde pescado dispuestas para el consumo en la Comunitat Valenciana, así como los factores asociados a dichas concentraciones y suevolución en el período 2011-2017. Métodos: Se realizó un estudio descriptivo, retrospectivo, de los niveles de Hg en muestras de pescado y de su evolucióntemporal, tanto en general como por grupos de pescado. Los datos proceden delPrograma de Vigilancia Sanitaria de Alimentos de laGeneralitat Valenciana. Se construyeron modelos de regresión lineal multivariantes para evaluar la asociación del año de muestreo,el grupo de pescado y el origen del mismo con las concentraciones de THg (n=560) y MeHg (n=206). Se evaluó la tendencia anualmedia de los niveles de THg y MeHg a lo largo del período.Resultados: La mediana para THg fue de 0,20 mg/kg, y de 0,14 mg/kg para MeHg. El pez espada/emperador fue el grupo depescado que presentó niveles más altos, seguido del atún/bonito frescos y del atún en lata. La tendencia global de los niveles deTHg fue descendente ajustando por el peso anual de las muestras de pez espada/emperador. Al analizar la tendencia en pez espada/emperador se observó una disminución del 7% en promedio por año. Conclusiones: La evolución temporal de los niveles de THg en pescado en la Comunitat Valenciana en el período 2011-2017 presenta una tendencia global descendente cuando se ajusta por el peso relativo de pez/espada emperador sobre el total de muestraspara cada año. Además, al estudiar los niveles de THg en este grupo se observa una tendencia decreciente.(AU)

Background: Mercury (Hg) is a toxic metal, and dietary exposure is the main one in humans, especially fish consumption. Inorder to reduce Hg exposure, maximum levels in fish products have been established. We aimed to describe total mercury (THg) andmethylmercury (MeHg) concentrations in fish species consumed in Comunitat Valenciana, as well as factors associated and theirtendency during the period 2011-2017. Methods: A retrospective descriptive study of Hg levels in fish meat samples in Comunitat Valenciana between 2011 and 2017 andtheir temporal trend was carried out, both in general and by fish groups. Data comes from Generalitat Valenciana’sHealth Surveillance ofFood Program. We created multivariate linear regression models to evaluate the association between sampling year, fish group and originand THg (n=560) / MeHg (n=206) concentrations. The average annual trend of THg and MeHg levels throughout the period was evaluated. Results: The median was 0.20 mg/kg for THg and 0.14 mg/kg for MeHg. Swordfish, fresh tuna/albacore and canned tuna, in thatorder, showed the highest concentrations. Global tendency of THg levels was descending when adjusting by swordfish annual percentage. When we analized the tendency in swordfish, we observed a 7% decrease on average per year. Conclusions: Global temporal trend of THg levels in fish in Comunitat Valenciana during the period 2011-2017 is descending afteradjusting by the relative weight of swordfish over the total number of samples by year. We observe a descending tendency whenstudied by species (swordfish).(AU)

Influence of genetic polymorphisms on arsenic methylation efficiency during pregnancy: Evidence from a Spanish birth cohort.

BACKGROUND: Inorganic arsenic (iAs) is a widespread toxic metalloid. It is well-known that iAs metabolism and its toxicity are mediated by polymorphisms in AS3MT and other genes. However, studies during pregnancy are scarce. We aimed to examine the role of genetic polymorphisms in AS3MT, GSTO2, N6AMT1, MTHFR, MTR, FTCD, CBS, and FOLH1 in iAs methylation efficiency during pregnancy. METHODS: The study included 541 pregnant participants from the INMA (Environment and Childhood) Spanish cohort. Using high-performance liquid chromatography coupled to inductively coupled plasma-tandem mass, we measured arsenic (iAs and the metabolites monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)) in urine samples collected during the first trimester. iAs methylation efficiency was determined based on relative concentrations of the As metabolites in urine (%MMA, %DMA, and %iAs). Thirty-two single nucleotide polymorphisms (SNPs) in nine genes were determined in maternal DNA; AS3MT haplotypes were inferred. We assessed the association between genotypes/haplotypes and maternal As methylation efficiency using multivariate linear regression models. RESULTS: The median %MMA and %DMA were 5.3 %, and 89 %, respectively. Ancestral alleles of AS3MT SNPs (rs3740393, rs3740390, rs11191453, and rs11191454) were significantly associated with higher %MMA, %iAs, and lower %DMA. Pregnant participants with zero copies of the GGCTTCAC AS3MT haplotype presented a higher %MMA. Statistically significant associations were also found for the FOLH1 SNP rs202676 (ß 0.89 95%CI: 0.24, 1.55 for carriers of the G allele vs. the A allele). CONCLUSIONS: Our study shows that ancestral alleles in AS3MT polymorphisms were associated with lower As methylation efficiency in early pregnancy and suggests that FOLH1 also plays a role in As methylation efficiency. These results support the hypothesis that As metabolism is multigenic, being a key element for identifying susceptible populations.

Exposure to mercury among Spanish adolescents: Eleven years of follow-up.

The toxic effects of mercury exposure on human health are a public health concern. The most important source of this exposure is the consumption of fish and marine mammals. This study aims to describe hair mercury concentrations and their evolution from birth until eleven years of age in adolescents from the INMA (Environment and Childhood) birth cohort study, and to assess the association of hair mercury concentrations at eleven years of age with sociodemographic and dietary factors. The sample comprised 338 adolescents from the sub-cohort of Valencia (in eastern Spain). Total mercury (THg) was measured in hair samples collected at 4, 9 and 11 years old and in cord blood at birth. The equivalent of hair for cord-blood THg concentrations was calculated. Fish consumption and other characteristics at 11 years old were collected through questionnaires. Multivariate linear regression models were conducted to explore the association between THg concentrations, fish consumption and covariates. The geometric mean of hair THg concentrations at 11 years of age was 0.86 µg/g (95%CI: 0.78-0.94) and 45.2% of the participants presented concentrations above the equivalent RfD proposed by the US EPA (1 µg/g). Consumption of fish such as swordfish, canned tuna and other large oily fish was associated with higher levels of hair mercury at 11 years of age. Swordfish had the highest effect with an increase of 125% in hair mercury (95%CI: 61.2-214.9%) given a 100 g/week increase in its consumption, and, taking into account the frequency of consumption, canned tuna was the main contributor to Hg exposure among our population. The hair THg concentrations at 11 years of age represented a reduction of around 69% with respect to that estimated at childbirth. Even though THg exposure shows a sustained decreasing trend, it can still be considered elevated. INMA birth cohort studies provide a longitudinal assessment of mercury exposure in a vulnerable population, its associated factors and temporal trends, and this information could be used to adjust recommendations about this issue.

Pre and postnatal exposure to mercury and sexual development in 9-year-old children in Spain: The role of brain-derived neurotrophic factor.

Early exposure to mercury has been related to endocrine disruption. Steroid hormones play a crucial role in neural cell migration, differentiation, etc., as well as protecting against several neurotoxic compounds. We investigate the relation between mercury exposure and children's sexual development, and we evaluate the possible influence of different brain-derived neurotrophic factor (BDNF) polymorphisms on this association. Our study sample comprised 412 9-year-old children participating in the INMA cohort (2004-2015). Mercury concentrations were measured at birth (cord blood) and at 4 and 9 years of age (hair). Sexual development was assessed by levels of sex steroid hormones (estradiol and testosterone) in saliva and the Tanner stages of sex development at 9 years (categorized as 1: prepuberty and >1: pubertal onset). Covariates and confounders were collected through questionnaires during pregnancy and childhood. Polymorphisms in the BDNF gene were genotyped in cord blood DNA. Multivariate linear regression analyses were performed between mercury levels and children's sexual development by sex. Effect modification by genetic polymorphisms and fish intake was assessed. We found marginally significant inverse associations between postnatal exposure to mercury (at 9 years) and testosterone levels (ß[95%CI] = -0.16[-0.33,0.001], and -0.20[-0.42,0.03], for boys and girls, respectively). Additionally, we found that prenatal mercury was negatively associated with Tanner stage >1 in boys. Finally, we found significant genetic interactions for some single nucleotide polymorphisms in the BDNF gene. In conclusion, pre and postnatal exposure to mercury seems to affect children's sexual development and BDNF may play a role in this association, but further research would be needed.

Assessment of barriers for people with disability to enjoy national parks.

There is increasing awareness of the importance of nature-based recreation to human wellbeing. Given its significant benefits, natural-protected area management has not always provided equitable access to all potential users. Limited research till now has been focused on how the outdoor barriers impact the equal enjoyment of people with mobility/motor disabilities (PwMDs) of nature when promoting sustainable nature-based tourism. This study intends to shed light on those aspects which constrain the PwMD's enjoyment of the great outdoors at national parks (NPs). The study was carried out in Canada and Spain through an online survey on amenities needed and accessibility barriers for PwMDs in parks. It was analyzed through log-linear models for cross-frequency tables, which allow us to estimate the associations between questions/variables and, thus, ultimately, obtain insights into how the needs of amenities and accessibility barriers can affect and limit PwMDs' enjoyment of natural parks. The results show a predisposition on the part of participants to enjoy parks more frequently than they usually do, as well as a preference for forests and mountain landscapes. Information and communication technologies are the tools most chosen to prepare for their trip and visit to the park. PwMD finds barriers in NPs as impediments to benefit from nature-based recreation and adding to their wellbeing. NP managers should take into consideration that PwMD's visits to parks are related to the main obstacles they perceive such as slopes and pavement and that they require amenities such as recreation and signposting. They would also like to enjoy parks more often, with footpaths suitable for walkability/wheelability, e.g., compact pavement, low inclines, and adequate signposting. In addition to the physical barriers, managers should also consider intrapersonal and interpersonal constraints to provide outdoor activities in parks focused on PwMDs' needs.

Prenatal arsenic exposure, arsenic methylation efficiency, and neuropsychological development among preschool children in a Spanish birth cohort.

BACKGROUND: Prenatal arsenic (As) exposure could negatively affect child neuropsychological development, but the current evidence is inconclusive. OBJECTIVES: To explore the relationship between prenatal urinary total As (TAs) concentrations, the As species and the methylation efficiency, and child neuropsychological development in a Spanish birth cohort. We also studied the effect modification produced by sex and several nutrients and elements. MATERIALS AND METHODS: Study subjects were 807 mother-child pairs participating in the INMA (Childhood and Environment) Project. Urinary TAs and its metabolites, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), inorganic As (iAs) and arsenobetaine were measured in the first trimester of pregnancy. Methylation efficiency was determined through the percentages of the metabolites and using principal component analysis. Children's neuropsychological development was assessed at the age of 4-5 years using the McCarthy Scales of Children's Abilities (MSCA). Multivariable linear regression models were built to assess the association between TAs, the As species and the maternal methylation efficiency, and the neuropsychological scores. We explored effect modification by sex, iron status, maternal nutrients status (serum manganese and selenium, and urinary zinc), and maternal vitamins intake (folate, and vitamins B12 and B6). RESULTS: The geometric mean (95%CI) of ∑As (sum of DMA, MMA and iAs) was 7.78 (7.41, 8.17) µg/g creatinine. MMA concentrations were inversely associated with the scores for the general, verbal, quantitative, memory, executive function and working memory scales (i.e. ß [CI95%] = -1.37 [-2.33, -0.41] for the general scale). An inverse association between %MMA and the memory scores was found. Children whose mothers had lower manganese, zinc and ferritin concentrations obtained lower scores on several MSCA scales with decreasing As methylation efficiency. DISCUSSION: An inverse association was observed between MMA concentrations and children's neuropsychological development. Maternal levels of manganese, zinc and ferritin affected the association between As methylation efficiency and MSCA scores.

Exposure to metals and metalloids among pregnant women from Spain: Levels and associated factors.

BACKGROUND: Humans are regularly exposed to metals and metalloids present in air, water, food, soil and domestic materials. Most of them can cross the placental barrier and cause adverse impacts on the developing foetus. OBJECTIVES: To describe the prenatal concentrations of metals and metalloids and to study the associated sociodemographic, environmental and dietary factors in pregnant Spanish women. METHODS: Subjects were 1346 pregnant women of the INMA Project, for whom the following metals arsenic (As), cadmium (Cd), cobalt (Co), copper (Cu), molybdenum (Mo), nickel (Ni), lead (Pb), antimony (Sb), selenium (Se), thallium (Tl) and zinc (Zn) were determined in urine, at both the first and the third trimesters of gestation. Sociodemographic, dietary and environmental information was collected through questionnaires during pregnancy. Multiple linear mixed models were built in order to study the association between each metal and metalloid concentrations and the sociodemographic, environmental and dietary factors. RESULTS: The most detected compounds were As, Co, Mo, Sb, Se and Zn at both trimesters. Zn was the element found in the highest concentrations at both trimesters and Tl was detected in the lowest concentrations. We observed significant associations between As, Cd, Cu, Sb, Tl and Zn concentrations and working situation, social class and age. Seafood, meat, fruits, nuts, vegetables and alcohol intake affected the levels of all the metals but Cd and Cu. Proximity to industrial areas, fields and air pollution were related to all metals except Cd, Sb and Se. CONCLUSIONS: This is the first large prospective longitudinal study on the exposure to metals and metalloids during pregnancy and associated factors to include several cohorts in Spain. The present study shows that some modifiable lifestyles, food intakes and environmental factors could be associated with prenatal exposure to metal(loid)s, which may be considered in further studies to assess their relationship with neonatal health outcomes.

A Gaussian Process Model for Color Camera Characterization: Assessment in Outdoor Levantine Rock Art Scenes.

In this paper, we propose a novel approach to undertake the colorimetric camera characterization procedure based on a Gaussian process (GP). GPs are powerful and flexible nonparametric models for multivariate nonlinear functions. To validate the GP model, we compare the results achieved with a second-order polynomial model, which is the most widely used regression model for characterization purposes. We applied the methodology on a set of raw images of rock art scenes collected with two different Single Lens Reflex (SLR) cameras. A leave-one-out cross-validation (LOOCV) procedure was used to assess the predictive performance of the models in terms of CIE XYZ residuals and Δ E a b * color differences. Values of less than 3 CIELAB units were achieved for Δ E a b * . The output sRGB characterized images show that both regression models are suitable for practical applications in cultural heritage documentation. However, the results show that colorimetric characterization based on the Gaussian process provides significantly better results, with lower values for residuals and Δ E a b * . We also analyzed the induced noise into the output image after applying the camera characterization. As the noise depends on the specific camera, proper camera selection is essential for the photogrammetric work.

Grey level and noise evaluation of a Foveon X3 image sensor: a statistical and experimental approach.

Radiometric values on digital imagery are affected by several sources of uncertainty. A practical, comprehensive and flexible procedure to analyze the radiometric values and the uncertainty effects due to the camera sensor system is described in this paper. The procedure is performed on the grey level output signal using image raw units with digital numbers ranging from 0 to 2(12)-1. The procedure is entirely based on statistical and experimental techniques. Design of Experiments (DoE) for Linear Models (LM) are derived to analyze the radiometric values and estimate the uncertainty. The presented linear model integrates all the individual sensor noise sources in one global component and characterizes the radiometric values and the uncertainty effects according to the influential factors such as the scene reflectance, wavelength range and time. The experiments are carried out under laboratory conditions to minimize the rest of uncertainty sources that might affect the radiometric values. It is confirmed the flexibility of the procedure to model and characterize the radiometric values, as well as to determine the behaviour of two phenomena when dealing with image sensors: the noise of a single image and the stability (trend and noise) of a sequence of images.