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Cronin A, Tkaczyk ER, Hussain I, Bowden A, Saknite I. Effect of camera distance and angle on color of diverse skin tone-based standards in smartphone photos. JOURNAL OF BIOPHOTONICS 2023; 16:e202200381. [PMID: 36772956 PMCID: PMC10247498 DOI: 10.1002/jbio.202200381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 02/02/2023] [Accepted: 02/03/2023] [Indexed: 06/07/2023]
Abstract
Accurate and reproducible color capture is vital in medical photography. Camera distance and angle are particularly important as they are highly variable in a clinical setting. To account for variability in illumination, camera technology, and geometric effects, color standards are often used for color correction. To explore how geometry affects color, we quantified the change in CIELAB color value of a color standard for diverse skin tones at varying smartphone camera distances and angles. Whereas both chromaticity (a* and b*) and lightness (L*) were affected by angle, distance only affected L* (standard error of measurement, SEM > 1 CIELAB unit). Flash usage did not generally reduce distance and angle associated variability. Compared to compressed (JPG) format, raw (DNG) images had decreased median variability across different distances and angles. These findings suggest that in medical photography, inconsistent camera distance and angle can increase variability in photographed skin appearance over time.
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Affiliation(s)
- Austin Cronin
- Dermatology Service, Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee, USA
- Department of Dermatology, Vanderbilt Dermatology Translational Research Clinic, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Eric R. Tkaczyk
- Dermatology Service, Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee, USA
- Department of Dermatology, Vanderbilt Dermatology Translational Research Clinic, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Iftak Hussain
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Audrey Bowden
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
- Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Inga Saknite
- Department of Dermatology, Vanderbilt Dermatology Translational Research Clinic, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Biophotonics Laboratory, Institute of Atomic Physics and Spectroscopy, University of Latvia, Riga, Latvia
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Evaluation of the consistency of neonatal skin injury assessment using clinical images and the metric and graduated colour tool. J Tissue Viability 2022; 31:395-403. [DOI: 10.1016/j.jtv.2022.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/30/2022] [Accepted: 05/04/2022] [Indexed: 11/18/2022]
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Abstract
Whole slide imaging (WSI) has various uses, including the development of decision support systems, image analysis, education, conferences, and remote diagnostics. It is also used to develop artificial intelligence using machine learning methods. In the clinical setting, however, many issues have hindered the implementation of WSI. These issues are becoming more important as WSI is gaining wider use in clinical practice, particularly with the implementation of artificial intelligence in pathological diagnosis. One of the most important issues is the standardization of color for WSI, which is an important component of digital pathology. In this paper, we review the major factors of color variation and how to evaluate and modify color variation to establish color standardization. There are five major reasons for color variation, which include specimen thickness, staining, scanner, viewer, and display. Recognizing that the color is not standardized is the first step towards standardization, and it is difficult to ascertain whether the appropriate color of the WSI is displayed at the reviewers' end.
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Affiliation(s)
- Takashi Inoue
- Department of Pathology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.,Department of General Thoracic Surgery, Dokkyo Medical University, 880 Kitakobayashi, Mibu, Shimotuga-gun, Tochigi 3210293, Japan
| | - Yukako Yagi
- Department of Pathology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
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Karimi R, Afshar M, Salimian M, Sharif A, Hidariyan M. The Effect of Platelet Rich Plasma Dressing on Healing Diabetic Foot Ulcers. Nurs Midwifery Stud 2016. [DOI: 10.17795/nmsjournal30314] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Collings S, Thompson O, Hirst E, Goossens L, George A, Weinkove R. Non-Invasive Detection of Anaemia Using Digital Photographs of the Conjunctiva. PLoS One 2016; 11:e0153286. [PMID: 27070544 PMCID: PMC4829242 DOI: 10.1371/journal.pone.0153286] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 03/25/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND AND AIMS Anaemia is a major health burden worldwide. Although the finding of conjunctival pallor on clinical examination is associated with anaemia, inter-observer variability is high, and definitive diagnosis of anaemia requires a blood sample. We aimed to detect anaemia by quantifying conjunctival pallor using digital photographs taken with a consumer camera and a popular smartphone. Our goal was to develop a non-invasive screening test for anaemia. PATIENTS AND METHODS The conjunctivae of haemato-oncology in- and outpatients were photographed in ambient lighting using a digital camera (Panasonic DMC-LX5), and the internal rear-facing camera of a smartphone (Apple iPhone 5S) alongside an in-frame calibration card. Following image calibration, conjunctival erythema index (EI) was calculated and correlated with laboratory-measured haemoglobin concentration. Three clinicians independently evaluated each image for conjunctival pallor. RESULTS Conjunctival EI was reproducible between images (average coefficient of variation 2.96%). EI of the palpebral conjunctiva correlated more strongly with haemoglobin concentration than that of the forniceal conjunctiva. Using the compact camera, palpebral conjunctival EI had a sensitivity of 93% and 57% and specificity of 78% and 83% for detection of anaemia (haemoglobin < 110 g/L) in training and internal validation sets, respectively. Similar results were found using the iPhone camera, though the EI cut-off value differed. Conjunctival EI analysis compared favourably with clinician assessment, with a higher positive likelihood ratio for prediction of anaemia. CONCLUSIONS Erythema index of the palpebral conjunctiva calculated from images taken with a compact camera or mobile phone correlates with haemoglobin and compares favourably to clinician assessment for prediction of anaemia. If confirmed in further series, this technique may be useful for the non-invasive screening for anaemia.
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Affiliation(s)
- Shaun Collings
- Wellington School of Medicine, University of Otago, Wellington, New Zealand
- Malaghan Institute of Medical Research, Wellington, New Zealand
| | - Oliver Thompson
- Sensing and Automation Group, Callaghan Innovation, Lower Hutt, New Zealand
| | - Evan Hirst
- Sensing and Automation Group, Callaghan Innovation, Lower Hutt, New Zealand
| | - Louise Goossens
- Photography Department, Capital & Coast District Health Board, Wellington, New Zealand
| | - Anup George
- Wellington Blood & Cancer Centre, Capital & Coast District Health Board, Wellington, New Zealand
| | - Robert Weinkove
- Malaghan Institute of Medical Research, Wellington, New Zealand
- Wellington Blood & Cancer Centre, Capital & Coast District Health Board, Wellington, New Zealand
- Department of Pathology & Molecular Medicine, University of Otago Wellington, Wellington, New Zealand
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Thoonen G, Nys B, Vander Haeghen Y, De Roy G, Scheunders P. Automatic forensic analysis of automotive paints using optical microscopy. Forensic Sci Int 2016; 259:210-20. [DOI: 10.1016/j.forsciint.2015.12.040] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 12/14/2015] [Accepted: 12/27/2015] [Indexed: 11/26/2022]
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Abstract
The color error in images taken by digital cameras is evaluated with respect to its sensitivity to the image capture conditions. A parametric study was conducted to investigate the dependence of image color error on camera technology, illumination spectra, and lighting uniformity. The measurement conditions were selected to simulate the variation that might be expected in typical telemedicine situations. Substantial color errors were observed, depending on the measurement conditions. Several image post-processing methods were also investigated for their effectiveness in reducing the color errors. The results of this study quantify the level of color error that may occur in the digital camera image capture process, and provide guidance for improving the color accuracy through appropriate changes in that process and in post-processing.
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Affiliation(s)
- John Penczek
- National Institute of Standards and Technology, University of Colorado, MS 686.01, Rm. 1-3542, 325 Broadway, Boulder, CO, 80305-3328, USA,
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Bautista PA, Hashimoto N, Yagi Y. Color standardization in whole slide imaging using a color calibration slide. J Pathol Inform 2014; 5:4. [PMID: 24672739 PMCID: PMC3952402 DOI: 10.4103/2153-3539.126153] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 11/20/2013] [Indexed: 11/17/2022] Open
Abstract
Background: Color consistency in histology images is still an issue in digital pathology. Different imaging systems reproduced the colors of a histological slide differently. Materials and Methods: Color correction was implemented using the color information of the nine color patches of a color calibration slide. The inherent spectral colors of these patches along with their scanned colors were used to derive a color correction matrix whose coefficients were used to convert the pixels’ colors to their target colors. Results: There was a significant reduction in the CIELAB color difference, between images of the same H & E histological slide produced by two different whole slide scanners by 3.42 units, P < 0.001 at 95% confidence level. Conclusion: Color variations in histological images brought about by whole slide scanning can be effectively normalized with the use of the color calibration slide.
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Affiliation(s)
- Pinky A Bautista
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Noriaki Hashimoto
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Yukako Yagi
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA
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Krupinski EA, Silverstein LD, Hashmi SF, Graham AR, Weinstein RS, Roehrig H. Observer performance using virtual pathology slides: impact of LCD color reproduction accuracy. J Digit Imaging 2013; 25:738-43. [PMID: 22546982 DOI: 10.1007/s10278-012-9479-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The use of color LCDs in medical imaging is growing as more clinical specialties use digital images as a resource in diagnosis and treatment decisions. Telemedicine applications such as telepathology, teledermatology, and teleophthalmology rely heavily on color images. However, standard methods for calibrating, characterizing, and profiling color displays do not exist, resulting in inconsistent presentation. To address this, we developed a calibration, characterization, and profiling protocol for color-critical medical imaging applications. Physical characterization of displays calibrated with and without the protocol revealed high color reproduction accuracy with the protocol. The present study assessed the impact of this protocol on observer performance. A set of 250 breast biopsy virtual slide regions of interest (half malignant, half benign) were shown to six pathologists, once using the calibration protocol and once using the same display in its "native" off-the-shelf uncalibrated state. Diagnostic accuracy and time to render a decision were measured. In terms of ROC performance, Az (area under the curve) calibrated = 0.8570 and Az uncalibrated = 0.8488. No statistically significant difference (p = 0.4112) was observed. In terms of interpretation speed, mean calibrated = 4.895 s; mean uncalibrated = 6.304 s which is statistically significant (p = 0.0460). Early results suggest a slight advantage diagnostically for a properly calibrated and color-managed display and a significant potential advantage in terms of improved workflow. Future work should be conducted using different types of color images that may be more dependent on accurate color rendering and a wider range of LCDs with varying characteristics.
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Wu D, Sun DW. Colour measurements by computer vision for food quality control – A review. Trends Food Sci Technol 2013. [DOI: 10.1016/j.tifs.2012.08.004] [Citation(s) in RCA: 236] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Menesatti P, Angelini C, Pallottino F, Antonucci F, Aguzzi J, Costa C. RGB color calibration for quantitative image analysis: the "3D thin-plate spline" warping approach. SENSORS 2012; 12:7063-79. [PMID: 22969337 PMCID: PMC3435966 DOI: 10.3390/s120607063] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 05/14/2012] [Accepted: 05/22/2012] [Indexed: 11/27/2022]
Abstract
In the last years the need to numerically define color by its coordinates in n-dimensional space has increased strongly. Colorimetric calibration is fundamental in food processing and other biological disciplines to quantitatively compare samples' color during workflow with many devices. Several software programmes are available to perform standardized colorimetric procedures, but they are often too imprecise for scientific purposes. In this study, we applied the Thin-Plate Spline interpolation algorithm to calibrate colours in sRGB space (the corresponding Matlab code is reported in the Appendix). This was compared with other two approaches. The first is based on a commercial calibration system (ProfileMaker) and the second on a Partial Least Square analysis. Moreover, to explore device variability and resolution two different cameras were adopted and for each sensor, three consecutive pictures were acquired under four different light conditions. According to our results, the Thin-Plate Spline approach reported a very high efficiency of calibration allowing the possibility to create a revolution in the in-field applicative context of colour quantification not only in food sciences, but also in other biological disciplines. These results are of great importance for scientific color evaluation when lighting conditions are not controlled. Moreover, it allows the use of low cost instruments while still returning scientifically sound quantitative data.
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Affiliation(s)
- Paolo Menesatti
- Agricultural Engineering Research Unit of the Agricultural Research Council (CRA-ING), Via della Pascolare 16, Monterotondo scalo (Rome) 00015, Italy; E-Mails: (P.M.); (C.A.); (F.P.); (F.A.)
| | - Claudio Angelini
- Agricultural Engineering Research Unit of the Agricultural Research Council (CRA-ING), Via della Pascolare 16, Monterotondo scalo (Rome) 00015, Italy; E-Mails: (P.M.); (C.A.); (F.P.); (F.A.)
| | - Federico Pallottino
- Agricultural Engineering Research Unit of the Agricultural Research Council (CRA-ING), Via della Pascolare 16, Monterotondo scalo (Rome) 00015, Italy; E-Mails: (P.M.); (C.A.); (F.P.); (F.A.)
| | - Francesca Antonucci
- Agricultural Engineering Research Unit of the Agricultural Research Council (CRA-ING), Via della Pascolare 16, Monterotondo scalo (Rome) 00015, Italy; E-Mails: (P.M.); (C.A.); (F.P.); (F.A.)
| | - Jacopo Aguzzi
- Instituto de Ciencías del Mar (ICM-CSIC), Paseo Marítimo de la Barceloneta 37-49, Barcelona 08003, Spain; E-Mail:
| | - Corrado Costa
- Agricultural Engineering Research Unit of the Agricultural Research Council (CRA-ING), Via della Pascolare 16, Monterotondo scalo (Rome) 00015, Italy; E-Mails: (P.M.); (C.A.); (F.P.); (F.A.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +39-06-9067-5214; Fax: +39-06-9062-5591
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Ballesteros R, Bonsfills N, Chacón M, García-Lázaro J, Gómez-Barrena E. Histomorphometry of the ligaments using a generic-purpose image processing software, a new strategy for semi-automatized measurements. J Digit Imaging 2011; 25:527-36. [PMID: 22143412 DOI: 10.1007/s10278-011-9440-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Gold chloride technique can be combined with Adobe Photoshop® software to yield a quantitative assessment of the different areas in heterogeneous structures as are ligament. A semi-automatized method based on the sum of two- and three-dimensional morphological criteria upon colorimetric criteria allows the identification and measurement of the area occupied by a structure of interest. It also allows the quantification of color intensity to differentiate structures with similar staining avidity, like vessels and nerves. This computer-assisted, semiquantitative procedure for computerized morphometry is relatively simple to perform. The accuracy, efficiency, and reproducibility of this method based on a commercially available imaging program were considered adequate when tested on the anterior cruciate ligament of the cat. Image normalization by trained observers using a commercially available software package designed for photography, applied to a sample randomly chosen, has provided the means of making reproducible measurements of heterogeneous structures.
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Affiliation(s)
- Rafael Ballesteros
- Department of Orthopedics, Universitary Hospital of Fuenlabrada, Camino del Molino 2, Fuenlabrada, 28942, Madrid, Spain.
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Iizaka S, Sugama J, Nakagami G, Kaitani T, Naito A, Koyanagi H, Matsuo J, Kadono T, Konya C, Sanada H. Concurrent validation and reliability of digital image analysis of granulation tissue color for clinical pressure ulcers. Wound Repair Regen 2011; 19:455-63. [PMID: 21518090 DOI: 10.1111/j.1524-475x.2011.00686.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Granulation tissue color is one indicator for pressure ulcer (PU) assessment. However, it entails a subjective evaluation only, and quantitative methods have not been established. We developed color indicators from digital image analysis and investigated their concurrent validity and reliability for clinical PUs. A cross-sectional study was conducted on 47 patients with 55 full-thickness PUs. After color calibration, a wound photograph was converted into three images representing red color: erythema index (EI), modified erythema index with additional color calibration (granulation red index [GRI]), and , which represents the artificially created red-green axis of L(*) a(*) b(*) color space. The mean intensity of the granulation tissue region and the percentage of pixels exceeding the optimal cutoff intensity (% intensity) were calculated. Mean GRI (ρ=0.39, p=0.007) and (ρ=0.55, p<0.001), as well as their % intensity indicators, showed positive correlations with a(*) measured by tristimulus colorimeter, but erythema index did not. They were correlated with hydroxyproline concentration in wound fluid, healthy granulation tissue area, and blood hemoglobin level. Intra- and interrater reliability of the indicator calculation using both GRI and had an intraclass correlation coefficient >0.9. GRI and from digital image analysis can quantitatively evaluate granulation tissue color of clinical PUs.
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Affiliation(s)
- Shinji Iizaka
- Department of Gerontological Nursing/Wound Care Management, Division of Health Sciences and Nursing, Graduate School of Medicine, The University of Tokyo, Japan
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Van Poucke S, Nelissen R, Jorens P, Vander Haeghen Y. Comparative analysis of two methods for wound bed area measurement. Int Wound J 2011; 7:366-77. [PMID: 20609029 DOI: 10.1111/j.1742-481x.2010.00701.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Wound bed area measurements are considered to be an essential part of the wound assessment process. Wound care professionals should be aware of the reliability and validity of the techniques they use. The purpose of this study was to assess whether wound care professionals are able to make as accurate and reproducible a measurement of the wound bed area using two methods for area measurement. Five wound care professionals independently assessed 2285 digital wound images for the wound bed area. Each image was measured in random order, three times, and in four angles by providing the rotated versions of each image (0°, 90°, 180° and 270°). Two techniques were compared: free hand drawing and closed polygon (CP) graph algorithm. Comparison of the two techniques showed differences that are, in our opinion, not acceptable in clinical practice when these techniques are used interchangeably and/or the measurements are carried out by different observers. Variations observed between wounds and observers seem related to the difference in perception of the wound bed margin. Our results indicate that repetition of CP graph area measurement results in the lowest difference in repetitive measurements. Study limitations are related to an incomplete consensus on definitions of wound, wound bed, wound edge and wound border. The development of an ontology related to wound images could aid to reduce these ambiguities.
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Affiliation(s)
- Sven Van Poucke
- Department of Anaesthesia, Critical Care, Emergency Care ZOL, Genk, Belgium.
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