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analytikLtd

VideometerLab 3 Multi-Spectral Imaging

Rapid Non-destructive Surface Analysis

Adrian Waltho, Analytik Ltd (Cambridge, UK)

adrian.waltho@analytik.co.uk

www.analytik.co.uk/multispectral-imaging

Light reflectance surface mapping for accurate measurement of colour, texture,

shape, size and chemical composition

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• Nuanced, human-like analysis of heterogeneous samples

• Objective, accurate, repeatable measurements

• Non-destructive analysis allows further sample assay work

• No sample preparation is required

• Rapid data acquisition and analysis allows high throughput screening

Why use Multispectral Imaging?

• Hybrid between spectroscopy and imaging

• Allows rapid, accurate and reproducible analysis of spectral AND spatial features including shape, colour, texture, size, surface chemistry and chemical composition

• The flexibility of the VideometerLab software unlocks many different application possibilities with the same hardware

• Advanced signal processing and statistical analysis algorithms allow fast, objective, repeatable, non-destructive analysis of any heterogeneous surface

Multispectral Imaging with VideometerLab 3

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What makes the VideometerLab unique? • The VideometerLab 3 provides 90% of the

performance of a hyperspectral imaging system at a fraction of the cost

• VideometerLab’s patented LED illumination system ensures high signal to noise ratio across the UV-Vis-VNIR spectrum (375nm-970nm at spaced intervals)

• Hyperspectral systems use a broadband illumination source, with a fixed intensity at each wavelength. The detector sensitivity can’t be changed, forcing a compromise that doesn’t use the optimum sensitivity at any wavelength and results in poor signal to noise

• LED illumination allows precise control of lighting conditions at each chosen LED wavelength allowing tuneable optimised illumination for any given sample surface

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• CIELab colour quantification and sRGB simulation under specified lighting conditions

• Contaminant detection and identification

• Concentration distribution heterogeneity of pharmaceutical API in tablets

• Corrosion quantification and grading of machinery parts

• Agar plate colony counting of multiple species simultaneously

• Forensic analysis of fingerprints, bloodstains, inks, powder residues and questioned documents

• Grain hydration and viability scoring

Multispectral Imaging Application Examples

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Traditional colour imaging uses three broad bands of colour

Red, Green and Blue

Normal Colour Imaging

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Normal Colour Imaging

• RGB photographs have limited spectral resolution

• Chlorophyll a and b give almost the same RGB signal and are not spectrally separated

Chloro-a High Low High

Chloro-b High Low High

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Multispectral Imaging

Many images obtained at many different wavelengths

Ultraviolet Near-Infrared

IR Red Yellow Green Blue UV

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Multispectral Imaging

Chloro-a High Low Low High

Chloro-b Med High Med Low

• Using just 4 wavelength bands with tightly defined ranges, Chlorophyll a and b can easily be distinguished

• VideometerLab 3 uses 19 wavelength bands

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VideometerLab 3 Schematic Overview

• Narrowband illumination provided by 19 LEDs between 375-970nm

• Integrating sphere diffuses light onto sample

• 5Mp CCD camera captures reflectance data at each LED wavelength

• Optional emission filter wheel for fluorescence macro-imaging

• Optional bright-field or dark-field lighting for translucency or diffuse scattering imaging

CCD Camera

LEDs

Integrating sphere

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VideometerLab 3 Schematic Overview

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Sizing ring sRGB Watch sRGB

Perceptual Simulation • Here are standard-RGB (sRGB) images of a machine sizing ring and watch

strap as they appear in a normal photograph

• sRGB is the standard computer displays and printers use to render images

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Perceptual Simulation • Human visual perception is well characterised

and understood

• Each sRGB pixel tri-value is calculated using the known %age reflectance values at wavelength bands within the visual range to render the image

• With 19 narrow-band reflectance values for each pixel, we have more detailed data than just 3 broad RGB values

• We can calculate the appearance of an object under any lighting condition

• Noon daylight

• Fluorescent light

• Tungsten bulbs

• We can also view the ‘appearance’ at just one wavelength in greyscale, where black = 0% reflectance, white = max reflectance

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NIR 940nm Violet 405nm

Cyan 505nm

Yellow 570nm

Deep Red 780nm

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NIR 940nm

Data Mining Images

• We can quickly gather more data on Regions of Interest (ROIs)

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NIR 940nm

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NIR 940nm

False-colour Image Enhancement

Each pixel’s grey-scale value represents %age reflectance black = 0% reflectance white = max (22.17% reflectance)

We can enhance contrast to our eyes using the ‘Jet’ false-colour scheme Blue = 0% reflectance Red = max (22.17% reflectance)

Jet NIR 940nm

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Jet MNF Band 3

Image Data Statistical Transformation

Jet PCA Band 3

• Statistical data manipulation algorithms transform image data-cube to highlight spatial-spectral trends

• Mathematics born from satellite imaging and remote sensing field

• 19 Wavelength bands 19 Transformation bands

Minimum Noise Fraction (MNF) Principal Components Analysis (PCA)

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MNF Band 3 PCA Band 3

MNF Band 4 PCA Band 4

MNF Band 5 PCA Band 5

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Trained Image Data Transformation • Guided statistical transformations allow us to compare ROIs directly by

training the transformation algorithm on known data sets • Paint two known conditions to highlight training sets • All other pixels scored on their similarity to training set pixels • Pixel’s entire spectral identity incorporated into weighting parameters • nCDA – normalised Canonical Discrimination Analysis

Jet NIR 940nm

Paint ROIs

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Trained Image Data Transformation

Jet NIR 940nm Jet nCDA transform

Blue = 0% 940nm reflectance Red = max 22.17% 940nm reflectance

Blue = pixels most like ROI 1 Red = pixels most like ROI 2

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Trained Image Data Transformation • Guided nCDA transformations allow us to compare ROIs in

separate images • Sample comparisons • Time lapse studies • Quantifiable, objective and reproducible data for rapid

analysis in research projects

Jet NIR 940nm Jet NIR 940nm

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Jet nCDA transform Jet nCDA transform

Trained Image Data Transformation

Blue = most like watch strap pixels Red = most like sizing ring ROI 2 pixels

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Trained Image Data Transformation

• The trained discrimination algorithm has highlighted an area of blue-scoring pixels on the sizing ring (circled)

• This tells us something about a common chemical identity between the watch strap material and a defined region of the sizing ring surface

Multispectral Image Data Analysis • A variety of image processing

tools and multivariate statistical transforms are available in VideometerLab’s analysis software

• Analysis routines and models can be saved and applied to new samples

• Multiple routines can be run on the same image data to quantify separate parameters

• Routines can be batch-run to aid in high-throughput data acquisition

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• Hardware options

• Emission Filter wheel (4 x 25mm Ø) for fluorescence macro-imaging

• Dark- or Bright-field backlighting for scattering or translucency analysis

• Vibratory feeder for automatic presentation of granular samples

• Software options

• Image Processing Toolbox for filtering and segmentation of image data in individual spectral bands

• Multispectral Imaging Toolbox for multi-variate image analysis and modelling

• Blob Toolbox for object separation, analysis and data output reporting

Hardware and Software Options

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• Hardware warranty and Software support for one year included with purchase

• Software Support Hotline service for simple protocol development helps guide you through image analysis steps (more complicated protocol development is available as a paid service)

• Software updates released on a regular basis (daily build available)

• On site repair response in 3 days

Post Sales Support

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• Nuanced, human-like analysis of heterogeneous samples

• Sophisticated data analysis tools for the novice and power user

• Objective, repeatable data collection with easy export

• Rapid, non-destructive testing with no sample preparation

VL3 Multispectral Imaging

adrian.waltho@analytik.co.uk

Multispectral imaging at Analytik.co.uk

VL3 Datasheet PDF