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Purpose: Clinicians commonly assess posture in persons with musculoskeletal disorders and tend to do so subjectively. Evidence-based practice requires the use of valid, reliable and sensitive tools to monitor treatment effectiveness. The purpose of this article was to determine which methods were used to assess posture quantitatively in a clinical setting and to identify psychometric properties of posture indices measured from these methods or tools., Methods: We conducted a comprehensive literature review. Pertinent databases were used to search for articles on quantitative clinical assessment of posture. Searching keywords were related to posture and assessment, scoliosis, back pain, reliability, validity and different body segments., Results: We identified 65 articles with angle and distance posture indices that corresponded to our search criteria. Several studies showed good intra- and inter-rater reliability for measurements taken directly on the persons (e.g., goniometer, inclinometer, flexible curve and tape measurement) or from photographs, but the validity of these measurements was not always demonstrated., Conclusion: Taking measurements of all body angles directly on the person is a lengthy process and may affect the reliability of the measurements. Measurement of body angles from photographs may be the most accurate and rapid way to assess global posture quantitatively in a clinical setting.

Background: The goal of this study was to determine the validity and reliability of assessing the presence of plantar foot ulceration and pre-ulcerative lesions in diabetes patients from digital photographs that were produced using a new photographic foot imaging device., Methods: In 32 diabetes patients who had a foot ulcer or were at high risk of ulceration (a total of 60 feet), high-quality photographic images of the plantar foot surface were collected. Each foot was assessed live, from photographs 2 weeks later, and again 4 weeks later for the presence of an ulcer, abundant callus, or the absence of signs. Each foot was assessed by four independently operating foot care specialists. Agreement scores were calculated using κ values (range, 0-1). Sensitivity and specificity scores were also calculated., Results: Foot ulceration was cumulatively scored 59 times, callus 78 times, and absence of signs 149 times during live assessment. Agreement with photographic assessment was very good for ulcer (κ = 0.87) and absence of signs (κ = 0.83) and good for callus (κ = 0.61). Sensitivity and specificity were high for ulcer (88% and 98%, respectively), callus (69% and 89%, respectively), and absence of signs (both 90%). Intra-observer agreement between repeated photographic assessments was good to excellent for all outcomes and observers (κ between 0.70 and 1.00). Inter-observer agreement for photographic assessments was good for ulcer (κ = 0.72-0.88) and absence of signs (κ = 0.59-0.75) and moderate to good for callus (κ = 0.48-0.73). For live assessment, inter-observer agreement scores were only slightly higher., Conclusions: The data illustrate that diabetic foot ulcers and pre-ulcerative lesions can be diagnosed in a valid and reliable manner by trained professionals from digital photographs produced with the foot imaging device. This supports the intended use of the device as a telemedical monitoring tool in the home environment for early detection of diabetic foot disease and prevention of severe complications in high-risk diabetes patients.

The improved designs of intraocular lenses (IOLs) implanted during cataract surgery demand understanding of the possible effects of lens misalignment on optical performance. In this review, we describe the implementation, set-up and validation of two methods to measure in vivo tilt and decentration of IOLs, one based on Purkinje imaging and the other on Scheimpflug imaging. The Purkinje system images the reflections of an oblique collimated light source on the anterior cornea and anterior and posterior IOL surfaces and relies on the well supported assumption of the linearity of the Purkinje images with respect to IOL tilt and decentration. Scheimpflug imaging requires geometrical distortion correction and image processing techniques to retrieve the pupillary axis, IOL axis and pupil centre from the three-dimensional anterior segment image of the eye. Validation of the techniques using a physical eye model indicates that IOL tilt is estimated within an accuracy of 0.261 degree and decentration within 0.161 mm. Measurements on patients implanted with aspheric IOLs indicate that IOL tilt and decentration tend to be mirror symmetric between left and right eyes. The average tilt was 1.54 degrees and the average decentration was 0.21 mm. Simulated aberration patterns using custom models of the patients eyes, built using anatomical data of the anterior cornea and foveal position, the IOL geometry and the measured IOL tilt and decentration predict the experimental wave aberrations measured using laser ray tracing aberrometry on the same eyes. This reveals a relatively minor contribution of IOL tilt and decentration on the higher-order aberrations of the normal pseudophakic eye.

We present a new method for viewpoint independent gait biometrics. The system relies on a single camera, does not require camera calibration, and works with a wide range of camera views. This is achieved by a formulation where the gait is self-calibrating. These properties make the proposed method particularly suitable for identification by gait, where the advantages of completely unobtrusiveness, remoteness, and covertness of the biometric system preclude the availability of camera information and specific walking directions. The approach has been assessed for feature extraction and recognition capabilities on the SOTON gait database and then evaluated on a multiview database to establish recognition capability with respect to view invariance. Moreover, tests on the multiview CASIA-B database, composed of more than 2270 video sequences with 65 different subjects walking freely along different walking directions, have been performed. The obtained results show that human identification by gait can be achieved without any knowledge of internal or external camera parameters with a mean correct classification rate of 73.6% across all views using purely dynamic gait features. The performance of the proposed method is particularly encouraging for application in surveillance scenarios.

Objective: A high prevalence of poor standing posture among elementary schoolchildren indicates the need for the introduction of school-based interventions for improvement of postural alignments. For assessing the effect of intervention programs, reliable quantitative measures of standing posture should be used. Therefore, the purpose of this study was to examine the reliability of a photographic method for assessment of standing posture among elementary schoolchildren., Methods: The study was conducted on a convenience sample of 273 male students between 10 and 13 years old. Each subject was photographed in habitual standing posture, 3 times in a front view and 3 times in a side view. Deviations from ideal postural alignment were calculated with Posture Image Analyzer software and UTHSCSA ImageTool software. Interitem reliability was estimated using intraclass correlation coefficient., Results: Intraclass correlation coefficients for posture deviations assessed with Posture Image Analyzer ranged from 0.81 for knee joints deviation and ankle joints deviation in the coronal plane to 0.92 for trunk deviation and knee joints deviation in the sagittal plane. Intraclass correlation coefficients for posture deviations assessed with UTHSCSA ImageTool ranged from 0.80 for knee joints deviation in the coronal plane to 0.91 for trunk deviation and knee joints deviation in the sagittal plane., Conclusions: This study showed a satisfactory interitem reliability of a photographic method for the assessment of standing posture among elementary schoolchildren., (Copyright 2010 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.)

We propose a simple and practical calibration technique that effectively estimates camera parameters from just five points on two orthogonal 1-D objects, each which has three collinear points, one of which is shared. We derive the basic equations needed to realize camera calibration from just five points observed on a single image that captures the objects. We describe a new camera calibration algorithm that estimates the camera parameters based on the basic equations and optimizes them by the bundle adjustment technique. Our method is validated by both computer simulated data and real images. The results show that the camera parameters yielded by our method are close to those yielded by existing methods. The tests demonstrate that our method is both effective and practical.

Background: Recently, digital photography in medicine is considered an acceptable tool in many clinical domains, e.g. wound care. Although ever higher resolutions are available, reproducibility is still poor and visual comparison of images remains difficult. This is even more the case for measurements performed on such images (colour, area, etc.). This problem is often neglected and images are freely compared and exchanged without further thought., Methods: The first experiment checked whether camera settings or lighting conditions could negatively affect the quality of colorimetric calibration. Digital images plus a calibration chart were exposed to a variety of conditions. Precision and accuracy of colours after calibration were quantitatively assessed with a probability distribution for perceptual colour differences (dE&#95;ab). The second experiment was designed to assess the impact of the automatic calibration procedure (i.e. chart detection) on real-world measurements. 40 Different images of real wounds were acquired and a region of interest was selected in each image. 3 Rotated versions of each image were automatically calibrated and colour differences were calculated., Results: 1st, Experiment: Colour differences between the measurements and real spectrophotometric measurements reveal median dE&#95;ab values respectively 6.40 for the proper patches of calibrated normal images and 17.75 for uncalibrated images demonstrating an important improvement in accuracy after calibration. The reproducibility, visualized by the probability distribution of the dE&#95;ab errors between 2 measurements of the patches of the images has a median of 3.43 dE* for all calibrated images, 23.26 dE&#95;ab for all uncalibrated images. If we restrict ourselves to the proper patches of normal calibrated images the median is only 2.58 dE&#95;ab! Wilcoxon sum-rank testing (p < 0.05) between uncalibrated normal images and calibrated normal images with proper squares were equal to 0 demonstrating a highly significant improvement of reproducibility. In the second experiment, the reproducibility of the chart detection during automatic calibration is presented using a probability distribution of dE&#95;ab errors between 2 measurements of the same ROI., Conclusion: The investigators proposed an automatic colour calibration algorithm that ensures reproducible colour content of digital images. Evidence was provided that images taken with commercially available digital cameras can be calibrated independently of any camera settings and illumination features.

Optic disc photography is used in the management and study of glaucoma. Quality assessment is needed at the time of acquisition and during review. A computerized algorithm for objective quality assessment was developed to mimic the procedure used by human observers. It was tested on film-based images obtained with mydriasis (40 normal and 46 glaucomatous eyes) and non-mydriatic digital images (30 normal and 38 glaucomatous eyes). The image sharpness was graded by six masked readers into four categories. The area under the receiver operating characteristic curve for identifying unreadable images was 1.0 for the digital and film-based images and 0.91 and 1.0 for differentiating between unreadable and mediocre images for digital and film-based images, respectively. This pilot study demonstrates that the algorithm can identify all unreadable images. Further studies are necessary to test whether it can be applied to images obtained in other locations on the fundus and with additional cameras., (Copyright 2010, SLACK Incorporated.)

We report a new method for determining the energy resolution of time-of-flight spectrometers for detecting photoelectrons produced with attosecond XUV pulses. By measuring the width of the 2s2p autoionization line of helium, we found the resolution of our spectrometer to be approximately 0.6 eV for electrons at 35.5 eV. Furthermore, the resolution in the 10 to 35 eV range was determined by applying a retarding potential at the entrance of the drift tube.

There are increasing applications that require precise calibration of cameras to perform accurate measurements on objects located within images, and an automatic algorithm would reduce this time consuming calibration procedure. The method proposed in this article uses a pattern similar to that of a chess board, which is found automatically in each image, when no information regarding the number of rows or columns is supplied to aid its detection. This is carried out by means of a combined analysis of two Hough transforms, image corners and invariant properties of the perspective transformation. Comparative analysis with more commonly used algorithms demonstrate the viability of the algorithm proposed, as a valuable tool for camera calibration.

Objective: To assess the accuracy of portion-size estimates and participant preferences using various presentations of digital images., Design: Two observational feeding studies were conducted. In both, each participant selected and consumed foods for breakfast and lunch, buffet style, serving themselves portions of nine foods representing five forms (eg, amorphous, pieces). Serving containers were weighed unobtrusively before and after selection as was plate waste. The next day, participants used a computer software program to select photographs representing portion sizes of foods consumed the previous day. Preference information was also collected. In Study 1 (n=29), participants were presented with four different types of images (aerial photographs, angled photographs, images of mounds, and household measures) and two types of screen presentations (simultaneous images vs an empty plate that filled with images of food portions when clicked). In Study 2 (n=20), images were presented in two ways that varied by size (large vs small) and number (4 vs 8)., Subjects/setting: Convenience sample of volunteers of varying background in an office setting., Statistical Analyses Performed: Repeated-measures analysis of variance of absolute differences between actual and reported portions sizes by presentation methods., Results: Accuracy results were largely not statistically significant, indicating that no one image type was most accurate. Accuracy results indicated the use of eight vs four images was more accurate. Strong participant preferences supported presenting simultaneous vs sequential images., Conclusions: These findings support the use of aerial photographs in the automated self-administered 24-hour recall. For some food forms, images of mounds or household measures are as accurate as images of food and, therefore, are a cost-effective alternative to photographs of foods., (Copyright 2010 American Dietetic Association. Published by Elsevier Inc. All rights reserved.)

We present algorithms for plane-based calibration of general radially distorted cameras. By this, we understand cameras that have a distortion center and an optical axis such that the projection rays of pixels lying on a circle centered on the distortion center form a right viewing cone centered on the optical axis. The camera is said to have a single viewpoint (SVP) if all such viewing cones have the same apex (the optical center); otherwise, we speak of NSVP cases. This model encompasses the classical radial distortion model [5], fisheyes, and most central or noncentral catadioptric cameras. Calibration consists in the estimation of the distortion center, the opening angles of all viewing cones, and their optical centers. We present two approaches of computing a full calibration from dense correspondences of a single or multiple planes with known euclidean structure. The first one is based on a geometric constraint linking viewing cones and their intersections with the calibration plane (conic sections). The second approach is a homography-based method. Experiments using simulated and a broad variety of real cameras show great stability. Furthermore, we provide a comparison with Hartley-Kang's algorithm [12], which, however, cannot handle such a broad variety of camera configurations, showing similar performance.

Purpose: Retinal images acquired by means of digital photography are often used for evaluation and documentation of the ocular fundus, especially in patients with diabetes, glaucoma or age-related macular degeneration. The clinical usefulness of an image is highly dependent on its quality. We set out to develop and evaluate an automatic method of evaluating the quality of digital fundus photographs., Methods: A method for making a numerical quantification of image sharpness and illumination was developed using Matlab image analysis functions. Based on their sharpness and illumination measures, 1000 fundus photographs, randomly selected from a clinical database, were assigned to four predefined quality groups (not acceptable, acceptable, good, very good). Six independent observers, comprising three experienced ophthalmologists and three ophthalmic nurses with extensive experience in fundus image acquisition, classified a selection of 100 of these images into the corresponding quality groups., Results: Automatic quality evaluation was more sensitive than evaluation by human observers in terms of ability to discriminate between good and very good images. The median concordance between the six human observers and the automatic evaluation was substantial (kappa = 0.64)., Conclusions: The proposed method provides an objective quality assessment of digital fundus photographs which agrees well with evaluations made by qualified human observers and which may be useful in clinical practice.

Purpose: We set out to quantify changes in the anterior chamber volume (ACV), anterior chamber depth (ACD) and anterior chamber angle (ACA) measurements obtained by the Pentacam rotating Scheimpflug camera following uneventful phacoemulsification surgery in normotensive eyes with open iridocorneal angles., Methods: We enrolled 44 eyes of 44 consecutive patients undergoing cataract extraction in this prospective study. Patients with a history of glaucoma, angle-closure glaucoma or any other concurrent ocular disease were excluded. A detailed eye examination including intraocular pressure (IOP) measurement was performed and ACV, ACD and inferior, superior, temporal and nasal ACA measurements were obtained in each patient eye using the Pentacam Comprehensive Eye Scanner (Pentacam CES) before and 3 months after phacoemulsification and intraocular lens (IOL) implantation with temporal clear corneal incision. Data were compared using paired t-test and one-way anova., Results: Mean preoperative ACV, ACD, ACA and IOP measurements were 164.7 +/- 49.8 mm(3), 3.0 +/- 0.8 mm, 35.7 +/- 10.2 degrees and 15.8 +/- 3.7 mmHg, respectively. Three months postoperatively, mean ACV, ACD, ACA and IOP measurements were 200.9 +/- 33.3 mm(3), 3.9 +/- 0.9 mm, 41.5 +/- 6.5 degrees and 13.2 +/- 3.9 mmHg, respectively. Postoperative mean ACV, ACD and ACA values in all four quadrants were significantly increased (p < 0.0001, p < 0.0001, p < 0.0001, respectively), whereas IOP was significantly reduced (p < 0.0001)., Conclusions: The Pentacam CES allowed very easy, fast, automatic and non-contact quantification of the anterior chamber parameters pre- and postoperatively in all patient eyes. Measurements obtained confirm that in normotensive eyes with open iridocorneal angles, the ACV and ACD increase and the ACA widens in all quadrants 3 months after uneventful phacoemulsification and IOL implantation. These changes are accompanied by a significant fall in IOP in the short term.

Purpose: To evaluate the accuracy of corneal power measurements by the Pentacam Scheimpflug system for intraocular lens (IOL) power calculation., Setting: Studio Oculistico d'Azeglio, Bologna, Italy., Methods: Consecutive patients having phacoemulsification and in-the-bag IOL implantation were prospectively studied. Intraocular lens power was calculated by entering 3 combinations of data into the Hoffer Q formula: (1) corneal power measurements by corneal topography (simulated keratometry) and axial length (AL) measurements by Ultrascan ultrasound (US) immersion biometry; (2) Scheimpflug corneal power measurements (simulated keratometry) and US AL measurements; (3) corneal power and AL measurements by partial coherence interferometry (PCI) (IOLMaster). The prediction error was calculated as the difference between the predicted and the measured refraction 1 month postoperatively., Results: Forty-one eyes were evaluated. The mean arithmetic error was zero for all combinations of measurements due to constant optimization. The mean absolute error (MAE) of the Scheimpflug-US combination was good (0.44 diopters [D] +/- 0.30 [SD]) but significantly higher than the topography-US combination and PCI (0.33 +/- 0.29 D and 0.33 +/- 0.23 D, respectively) (P = .043). The percentage of eyes with an MAE of 0.75 D or greater was higher with the Scheimpflug-US combination (7 eyes, 17%) than with the corneal topography-US combination (2 eyes, 4.8%) or PCI (3 eyes, 7.3%)., Conclusion: Corneal power measurements with the Pentacam Scheimpflug system should be used in IOL power calculation formulas with caution because the accuracy is good but is not as high as with standard measurement methods.

Purpose: To assess the repeatability and validity of lens densitometry derived from the Pentacam Scheimpflug imaging system., Setting: Eye Clinic, Queensland University of Technology, Brisbane, Australia., Methods: This prospective cross-sectional study evaluated 1 eye of subjects with or without cataract. Scheimpflug measurements and slitlamp and retroillumination photographs were taken through a dilated pupil. Lenses were graded with the Lens Opacities Classification System III. Intraobserver and interobserver reliability of 3 observers performing 3 repeated Scheimpflug lens densitometry measurements each was assessed. Three lens densitometry metrics were evaluated: linear, for which a line was drawn through the visual axis and a mean lens densitometry value given; peak, which is the point at which lens densitometry is greatest on the densitogram; 3-dimensional (3D), in which a fixed, circular 3.0 mm area of the lens is selected and a mean lens densitometry value given. Bland and Altman analysis of repeatability for multiple measures was applied; results were reported as the repeatability coefficient and relative repeatability (RR)., Results: Twenty eyes were evaluated. Repeatability was high. Overall, interobserver repeatability was marginally lower than intraobserver repeatability. The peak was the least reliable metric (RR 37.31%) and 3D, the most reliable (RR 5.88%). Intraobserver and interobserver lens densitometry values in the cataract group were slightly less repeatable than in the noncataract group., Conclusion: The intraobserver and interobserver repeatability of Scheimpflug lens densitometry was high in eyes with cataract and eyes without cataract, which supports the use of automated lens density scoring using the Scheimpflug system evaluated in the study.

Purpose: In an elderly Australian population, to evaluate the quality of fundus photographs taken non-mydriatically in both eyes, and to compare the quality of those taken second with those taken first., Methods: From 2258 participants (4516 images) aged 70 years and older who participated in the Melbourne Collaborative Cohort Study (MCCS), digital non-stereoscopic 45 degrees retinal photographs were taken with a Canon CR6-45NM Non-mydriatic Retinal Camera and evaluated. The quality of macular images was assessed as good, fair, and poor and McNemar's test was used to analyze variation in quality., Results: Gradable quality images were obtained from 95.8% eyes of participants, with 93.9% of participants having gradable photos of both eyes. The gradable rate for the eye photographed first (right), was significantly higher than that for the eye photographed second (left): 89.7% vs. 85.6%, respectively (difference of 4.12%, confidence interval [CI] of 2.68-5.54%, p < 0.001). The rate of ungradable photographs from the second eye was slightly greater than the first eye (4.5% and 3.8%, respectively), but the difference in proportion was not statistically significant (difference of 3.6%, CI of 0.17-1.5%, p = 0.384)., Conclusions: In the setting of a large elderly cohort study, non-dilated 45 degrees digital retinal imaging is an excellent method for fundus examination. It is fast, easy to use, non-invasive, and a reliable AMD (age-related macular degeneration)-detecting technique with only a minor loss of information from the second eye.

Background: Photographic severity scales depicting facial wrinkling are used extensively to assess the severity of skin ageing features, but they have been poorly investigated for their reproducibility., Objectives: To investigate the reproducibility of ordinal scales depicting four skin ageing features illustrated by reference photographs., Methods: A set of 253 images of caucasian women's faces was evaluated independently by four dermatologists using four different skin ageing severity scales: Larnier's overall photodamage, expression lines, glabellar frown lines, and wrinkles under the eyes. For each pair of dermatologists, degree of agreement was estimated using the weighted kappa statistic and degrees of distinguishability between adjacent categories along these scales were estimated using a recently developed log-linear method., Results: The kappa statistic highlighted substantial degrees of agreement between dermatologists for the glabellar frown lines scale, and the log-linear method did not evidence any scale defect. For the three other scales, only fair to moderate degrees of agreement were observed between dermatologists. In addition, difficulties in distinguishing between some adjacent categories were evidenced., Conclusions: The glabellar frown lines scale is a reproducible tool for assessment of the severity of facial wrinkling. The other scales should be redefined to improve their reproducibility, and therefore their quality, in future studies.

Measuring corneal diameter is often difficult in infants, but its importance in certain circumstances cannot be overstated. Most available techniques for obtaining corneal diameter measurement are threatening to the child: the gold standard measurement technique relies on calipers and a ruler and necessitates general anesthesia for most children under the age of 7 years. Consequently, this important element of the pediatric eye examination is often not performed in clinic. We describe and prospectively validate a digital photographic technique for measuring corneal diameter, which is easy to perform, quick, nonthreatening, and provides an accurate corneal diameter measurement.

We propose a new calibration method for a laser galvanometric scanning (LGS) system by adapting the camera model to model the LGS system. The similarity between the camera system and the LGS system has been investigated and exploited. The distortion parameters are acquired by solving a nonlinear least squares problem of 12 coefficients using the Levenberg-Marquardt algorithm. The efficiency of the calibration is improved. Experiments are conducted to verify the proposed model.

Objectives: To evaluate three different strategies (without or with mydriasis) for community based screening for sight threatening diabetic retinopathy (STDR)., Design: A masked cross-sectional comparative study., Setting: Primary care centre., Participants: 216 type-1 and type-2 diabetic patients (432 eyes)., Interventions: Screening for STDR was performed with the Topcon CRW6S non-mydriatic camera (NMC), compared with the grading of the seven-field standard stereoscopic photographs, 30 degrees field photographs with mydriasis as the gold standard method. Three fields were studied: Field 1 centred on the macula; field 2 centred on the disc and the macula and field 3 centred on the disc, on the macula and temporal upper to the macula all without and with mydriasis., Main Outcome Measures: Sensitivity and specificity of screening method and prevalence of STDR. Strategies: field 1 (macular), addition of field 2 (nasal), addition of field 3 (superior temporal) all without and with mydriasis., Results: The prevalence of STDR was 14.3%. When screening without mydriasis is performed, the percentage of referred patients increases from 14% (STDR) to almost 33% because of ungradable photographs. Sensitivity of detection of STDR by NMC using single field with mydriasis was 82% (95% confidence interval 72-92%) and without mydriasis 67% (54-80%). Specificity was 99% (97-100%) for single field with mydriasis and 99% (98-100%) without mydriasis. Sensitivity of detection using two fields with mydriasis was 95% (89-100%); without mydriasis (54-80%), slightly better than single field with mydriasis (72-92%). Specificity was similar., Conclusions: Screening for STDR with NMC can be performed effectively with one non-stereoscopic retinal photograph per eye with mydriasis using tropicamide 0.5%. Screening without mydriasis increases the number of patients to be referred.

The purpose of this study was to evaluate the validity of digital photographs for the assessment of the presence of pressure ulcers stage 2 or higher. Participants were 48 patients (28 white and 20 black) with pressure ulcers identified in the course of a wound specialist's routine clinical practice at the University of Maryland Medical Center. One pressure ulcer and one unaffected skin area were photographed on each participating patient. The gold standard diagnosis (stage 2 pressure ulcer vs. stage 1 or no pressure ulcer) was recorded by the wound specialist based on bedside examination. The photographs were reviewed blindly by another wound expert. The sensitivity of the blinded assessment was 97% (95% confidence interval [CI] 91-100%). The specificity was 97% (95% CI 92-100%). The sensitivity and specificity were both 100% in the white patients. In black patients, the sensitivity and specificity were 92% (95% CI 75-100%) and 93% (95% CI 82-100%), respectively. These results suggest that the use of photographic images to assess the presence or absence of a pressure ulcer stage 2 or higher has a high degree of validity. Since blinded outcome assessment is one of the cornerstones of good clinical trial design, photography offers the potential to strengthen future studies.

A dominant theme in vision research is that important characteristics of the visual pathway evolved to be effective in processing natural scenes. Given this perspective, one can learn about the nature of visual processing from a quantitative analysis of natural images. Such analysis can benefit from the camera as a measuring device. As such, the camera should not introduce arbitrary artifacts into the image formation process. This paper describes how to correct a number of unnecessary artifacts associated with obtaining natural scene statistics with a digital camera. For artifacts that are inherently part of image formation, and where elimination is not possible or appropriate, we describe methods for transformation and quantification.

Scheimpflug photography and densitometric image analysis are very precise techniques for light scattering measurement and biometry in the anterior segment of the eye. They provide reproducible data on the characteristics of the anterior eye segment in clinical and experimental studies and the set of data obtained allows discrimination of light scattering changes because of ageing, disease or toxic effects. The techniques can also be used to determine no-effect levels or maximally tolerable dosages of physical and chemical noxious factors. Several Scheimpflug cameras have been marketed, but the only cameras commercially available today are the Nidek EAS 1000 and the Oculus Pentacam. This review outlines the development of the technique and its introduction into ophthalmology. Furthermore, the application of the technique in clinical and experimental ophthalmology as well as in ocular toxicology are presented and discussed.

Digital cameras, when used correctly, can provide the basis for telemedicine services. The increasing sophistication of digital cameras, combined with the improved speed and availability of the Internet, make them an instrument that every health-care professional should be familiar with. Taking satisfactory images of patients requires clinical photography skills. Photographing charts, monitors, X-ray films and specimens also requires expertise. Image capture using digital cameras is often done with insufficient attention, which can lead to inaccurate study results. The procedures in clinical photography should not vary from camera to camera, or from country to country. Taking a photograph should be a standardised process. There are seven main scenarios in clinical photography and health professionals who use cameras should be familiar with all of them. Obtaining informed consent prior to photography should be a normal part of the clinical photography routine.

We investigated the use of camera phones for telehaematology. First, the minimum requirements for the camera phones to be used in telehaematology were investigated. A single image containing white cells, red cells and platelets was sent from a camera phone to 33 different camera phones. Nine of the camera phones were found to be unsuitable for telehaematology due to low display resolution or no zoom function of the image. Then we examined the agreement between a haematologist using a suitable camera phone for remote diagnosis and the blood film report made in the usual way. Blood samples were collected from nine patients who had conditions in which diagnostically important morphological abnormalities occurred. In seven of the nine cases, the telehaematology responses were similar to the documented blood film reports. We conclude that telehaematology using camera phones offers a quick and potentially valuable method of support for the diagnostic haematology laboratory.

Traditional methods for geometrical camera calibration are based on calibration grids or single pixel illumination by collimated light. A new method for geometrical sensor calibration by means of diffractive optical elements (DOE) in connection with a laser beam equipment is presented. This method can be especially used for 2D-sensor array systems but in principle also for line scanners., ((c) 2008 Optical Society of America)

Reasons for Performing Study: Rigorous evaluation of practicable methods for the objective assessment of foot conformation has not been performed., Objectives: To assess the practicability, precision and accuracy of the process of obtaining measurements of horses' feet using photography and image processing software., Methods: Precision study: Lateral photographs of horses' feet were obtained twice by 2 veterinary surgeons (image acquisition - IAc). Photographs were analysed by 2 masked veterinary surgeons on 2 occasions (image analysis - IAn). Measurements were compared within and between operators for self and non-self acquired photographs. Agreement indices (AIs) and 95% limits of agreement (LOA) were calculated for the IAn process alone and for the combined IAc + IAn processes. Accuracy study: Measurements obtained from lateral photographs were compared with those obtained from lateromedial radiographs. AIs and 95% LOA were calculated for each measurement., Results: Precision study: Mean intra- and interoperator AIs for the IAn process alone were > or = 0.90 while those for the combined IAc + IAn processes were > or = 0.89 for all measurements. Similar mean AIs and 95% LOA were calculated regardless of image origin. The 95% LOA for hoof angle, heel height/toe height% and coronary band angle for all comparisons were within target values. Accuracy study: Mean AIs were > or = 0.89 for all measurements. The 95% LOA for heel height/toe height% and coronary band angle were within target values., Conclusions: Excellent precision was identified within and between operators regardless of image origin. High levels of accuracy were also identified, especially for heel height/toe height% and coronary band angle, indicating that photography and radiography may be used interchangeably., Potential Relevance: Acquisition and analysis of photographic images is an appropriate method for the objective measurement of foot conformation, both in clinical and, research settings.

Background: Although intravenous fluorescein angiography (IVFA) is a relatively safe procedure, side effects have been shown to occur. The designed purpose of this study was to demonstrate a reduction in the frequency and severity of side effects during digital IVFA using 2 mL compared with 5 mL of 10% sodium fluorescein (NaFl). The secondary hypothesis was to show that no loss of image quality occurred with a reduction in the NaFl dose utilizing digital fluorescein angiography., Methods: A prospective study was initiated in which 1200 patients were randomized to 2 mL or 5 mL of 10% NaFl to allow for the evaluation of adverse events. Standard IVFA technique utilizing modern high-resolution digital photography was employed. Photographers evaluated the difficulty of image capture. A masked observer recorded all adverse events. Masked ophthalmologists evaluated image quality subjectively with a 4-point rating scale. Secondary to concerns regarding image quality, a masked interim analysis was carried out after 140 patients had been randomized., Results: A statistically significant reduction in the quality of angiograms (p = 0.0025) and ease of photography (p = 0.0012) was associated with 2 mL of NaFl, necessitating the termination of the study. Patients randomized to the 5 mL NaFl group experienced all 3 of the minor adverse events in the study. No statistically relevant conclusions could be obtained from this limited group., Interpretation: Two millilitres of NaFl for IVFA produces inferior quality digital images compared with 5 mL of NaFl. The potential reduction in adverse events associated with 2 mL of NaFl becomes unimportant in light of this significant finding regarding image quality.

Digital photography has virtually replaced conventional film photography as far as clinical imaging is concerned. Though most dermatologists are familiar with digital cameras, there is room for improvement in the quality of clinical images. We aim to give an overview of the basics of digital photography in relation to dermatology, which would be useful to a dermatologist in his or her future clinical practice.

Background: All the reported measures of sitting posture, as well as photographs, have one flaw, as these measures are external to the body. These measures use calculations from external bony landmarks to estimate spinal posture, on the understanding that what is being measured externally reflects the shape, health and performance of structures of the underlying spine. Without a comparative measure of the relative position of the structures of the spine, the validity of any external spinal posture measure cannot be established. This paper reports on a study which tests the validity of photographs to measure adolescent sitting posture., Methods: The study was conducted in a laboratory at the Department of Human Biology, University of Cape Town. A random sample of 40 adolescents were recruited from the Cape metropolitan schools, to detect differences of three degrees or more between the repeated measures of upright, normal or slouched posture (photographs) and between the posture photographs and LODOX measures. Eligible participants were healthy male and female subjects aged 15 or 16 years old, in Grade 10, and who were undertaking Computer or Computype studies at their schools. Two posture measurement tools were used in the study, namely: Photographs were taken using the Photographic Posture Analysis Method (PPAM) and Radiographs were taken using the LODOX (LODOX (Pty) Ltd) system. Subjects' posture was assessed in simulated computer workstations. The following angles were measured: the sagittal head angle, cervical angle, protraction/retraction angle, arm angle and the thoracic angle., Results: Data from 39 subjects (19 males, 20 females) was used for analysis (17 15-year-olds (7 boys and 10 girls), 22 16-year-olds (12 boys and 10 girls)). All but one photographic angle showed moderate to good correlation with the LODOX angles (Pearson r values 0.67-0.95) with the exception being the shoulder protraction/retraction angle Pearson r values. Bland Altman limits of agreement illustrated a slight bias for all angles. The reliability study findings from repeated photographs demonstrated moderate to good correlation of all angles (ICC values 0.78-0.99)., Conclusion: The findings of this study suggest that photographs provide valid and reliable indicators of the position of the underlying spine in sitting. Clinically it is important to know whether a patient is showing true progression in relation to a postural intervention. Based on the results of this study, the PPAM can be used in practice as a valid measure of sitting posture.

Purpose: To analyze brightness, contrast, and color balance of digital versus film retinal images in a multicenter clinical trial, to propose a model image from exemplars, and to optimize both image types for evaluation of age-related macular degeneration (AMD)., Methods: The Age-Related Eye Disease Study 2 (AREDS2) is enrolling subjects from 90 clinics, with three quarters of them using digital and one quarter using film cameras. Image brightness (B), contrast (C), and color balance (CB) were measured with three-color luminance histograms. First, the exemplars (film and digital) from expert groups were analyzed, and an AMD-oriented model was constructed. Second, the impact of B/C/CB on the appearance of typical AMD abnormalities was analyzed. Third, B/C/CB in AREDS2 images were compared between film (156 eyes) and digital (605 eyes), and against the model. Fourth, suboptimal images were enhanced by adjusting B/C/CB to bring them into accord with model parameters., Results: Exemplar images had similar brightness, contrast, and color balance, supporting an image model. Varying a specimen image through a wide range of B/C/CB revealed greatest contrast of drusen and pigment abnormalities against normal retinal pigment epithelium with the model parameters. AREDS2 digital images were more variable than film, with lower correspondence to our model. Ten percent of digital were too dim and 19% too bright (oversaturated), versus 1% and 4% of film, respectively. On average, digital had lower green channel contrast (giving less retinal detail) than film. Overly red color balance (weaker green) was observed in 23% of digital versus 8% of film. About half of digital (but fewer film) images required enhancement before AMD grading. After optimization of both image types, AREDS2 image quality was judged as good as that in AREDS (all film)., Conclusions: A histogram-based model, derived from exemplars, provides a pragmatic guide for image analysis and enhancement. In AREDS2, the best digital images matched the best film. Overall, however, digital provided lower contrast of retinal detail. Digital images taken with higher G-to-R ratio showed better brightness and contrast management. Optimization of images in the multicenter study helps standardize documentation of AMD (ClinicalTrials.gov NCT00345176).

Objective: To validate food photographs for food portion size estimation of frequently consumed dishes, to be used in a 24-hour recall food consumption study of pregnant women in a rural environment in Burkina Faso. This food intake study is part of an intervention evaluating the efficacy of prenatal micronutrient supplementation on birth outcomes., Subjects: Women of childbearing age (15-45 years)., Design: A food photograph album containing four photographs of food portions per food item was compiled for eight selected food items. Subjects were presented two food items each in the morning and two in the afternoon. These foods were weighed to the exact weight of a food depicted in one of the photographs and were in the same receptacles. The next day another fieldworker presented the food photographs to the subjects to test their ability to choose the correct photograph., Results: The correct photograph out of the four proposed was chosen in 55% of 1028 estimations. For each food, proportions of underestimating and overestimating participants were balanced, except for rice and couscous. On a group level, mean differences between served and estimated portion sizes were between -8.4% and 6.3%. Subjects who attended school were almost twice as likely to choose the correct photograph. The portion size served (small vs. largest sizes) had a significant influence on the portion estimation ability., Conclusions: The results from this study indicate that in a West African rural setting, food photographs can be a valuable tool for the quantification of food portion size on group level.

The authors reviewed and tested a range of equipment for their use in undertaking infrared (IR) and ultraviolet (UV) imaging in the digital workflow. In Part 1 the authors reported their findings with respect to undertaking IR imaging. Part 2 covers direct UV and UV fluorescence imaging.

Purpose: To assess the reproducibility of the evaluation of color photographs and fluorescein angiograms of the macula of each eye for patients enrolled in the Macular Photocoagulation Study (MPS) trials of laser photocoagulation of subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration., Methods: A total of 65 pre-enrollment and 26 posttreatment sets of photographs were regraded. The two gradings were compared on selected items judged to be of primary importance with respect to the role of the MPS Reading Center., Results: Agreement on eligibility of the neovascular lesion for an MPS trial was 88% (kappa statistic = 0.59); agreement on the size of the lesion was 86% (kappa statistic = 0.80); agreement on whether the lesion was covered by heavy treatment was 69% (kappa statistic = 0.35); and agreement on whether the treatment was in compliance with the study protocol was 73% (kappa statistic = 0.06)., Conclusions: Interpretation of photographs of eyes with CNV secondary to age-related macular degeneration for eligibility and size of the lesion was reproducible in the MPS. However, adequacy of laser photocoagulation treatment could not be determined reliably from photographs.

Objective: In diet surveys, quantitative underestimation of food consumption may be due to intentional misreporting or false portion-size reporting. Perception of food photographs used as aids for assessing the actual amounts may have an effect. This study was carried out to assess the validity of food photographs., Design: A real-time test protocol where 52 presented food servings were compared against photographed portions with similar food items., Subjects: Volunteers from the Rehabilitation Company Petrea (in Turku) were recruited, 161 adults participated, and for 146 subjects, complete data were collected., Methods: The proportions of correct estimations and reporting errors, in weights and percentages, are presented by gender and food group. Food descriptors, portion-size options and subject characteristics were studied as potential determinants of accuracy in portion-size estimation., Results: The total proportion of exactly correct estimations was 51% in men and 49% in women. The overall reporting error was -10 g in men and +1 g in women for the 52 food servings. Underreporting was typical for bread, spread and cold cuts and dishes in both genders. Over-reporting was typical for cereals in both genders and for snacks, vegetables and fruit in women. The estimation error was associated with the portion-size options but not associated with the energy density of food items, education or body mass index., Conclusions: Food portions in photographs seem to be a useful aid for the quantification of most food items. However, validation studies are needed to test the applicability of photographs for estimating current portions and for searching better tools in dietary surveys.

In many computer vision systems, it is assumed that the image brightness of a point directly reflects the scene radiance of the point. However, the assumption does not hold in most cases due to nonlinear camera response function, exposure changes, and vignetting. The effects of these factors are most visible in image mosaics and textures of 3D models where colors look inconsistent and notable boundaries exist. In this paper, we propose a full radiometric calibration algorithm that includes robust estimation of the radiometric response function, exposures, and vignetting. By decoupling the effect of vignetting from the response function estimation, we approach each process in a manner that is robust to noise and outliers. We verify our algorithm with both synthetic and real data which shows significant improvement compared to existing methods. We apply our estimation results to radiometrically align images for seamless mosaics and 3D model textures. We also use our method to create high dynamic range (HDR) mosaics which are more representative of the scene than normal mosaics.