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Table of Contents
Image quality — Sharpness — Other IQ factors — IQ Utilities — Getting started —
Imatest Instructions – general — Troubleshooting — Knowledge Base highlights —
Sharpness modules — Tone, Color, Noise & Dynamic Range modules — Spatial & Uniformity modules —
Miscellaneous modules and utilities — Industrial Testing edition — Appendix
| Offline (local) documentation Imatest documentation can now be viewed offline. Download this small (8MB) zip file (only the main documentation pages) to a convenient location, then unzip it. The Imatest site folder will contain a mirror of the Imatest documentation website (not the entire site, but including the Knowledge Base and News). Double-click on index.html to open a fully navigable mirror of this page in your web browser. To open documentation directly from Imatest Master, click on the Offline/Online Help button in the Help tab on the right of the Imatest main window, and follow the instructions. |
Image Quality
General — Introduction to Image Quality Factors
Image quality factors – Overview and Imatest measurements
Introduction – Summary table – Image quality factors – Sharpness – Noise – Dynamic range – Color accuracy – Distortion – Uniformity – Lateral chromatic aberration – Veiling glare – Color moire – Software artifacts – Data compression – Printer quality factors – Print Dmax – Print color gamut
Sharpness
Sharpness – What is it and how is it measured?
Introduction – MTF – MTF equation – Slanted-edge measurements – Why a slanted edge? – MTF measurement matrix – Spatial frequency units – Summary metrics – Results – Noise reduction – Diffraction & Optimum aperture – Interpreting MTF50 – Autofocus Speed – Calculation details – Imatest vs. ISO calculation – Links
Sharpening – and Standardized Sharpening for comparing cameras
Introduction – Examples – Over/Undersharpening – Examples – Unsharp masking (USM) – Links – Standardized sharpening
Slanted-edge versus Siemens Star – A comparison of sensitivity to signal processing
Introduction – Images – Raw results – Slanted-edge results – Sinusoidal (Log F-Contrast and Siemens star) results – Extreme sharpening – Summary – Conclusions
Slanted-edge versus Siemens Star, Part 2 – Results for four additional cameras
Slanted-edge measurement consistency and repeatability – comparing different ISO speeds and ROI sizes. Incomplete, but still useful.
Validating the Imatest slanted-edge calculation
LSF (Line Spread Function) correction factor for slanted-edge MTF measurements
Correcting nonuniform illumination in slanted-edge MTF measurements for nonuniformity perpendicular to the edge
Compensating camera MTF measurements for chart and sensor MTF
Introduction – Calculation – MTF compensation files – Applying the compensation – Lens MTF measurements
Chart Quality Calculator – determine the suitability of a chart (based on MTF measurements for specific media & print methods) for a specific application
Test chart suitability for MTF measurements – charts for determining the MTF measurement suitability of several media types (inkjet and photographic; reflective and transmissive). Based on Chart Quality Calculator results.
Chart Quality Index (CQI) – older (now deprecated) method that relates chart quality and size to MTF measurements. Replaced by Chart Quality Calculator. The Chart Finder is an interactive website for selecting chart size and media.
MTF curves and Image appearance – Correlating measurement with appearance
Introduction – The Slanted-edge test – Reference image – Sharpened images – Blurred images – Sharpened + blurred images – Observations – Sharpness ranking – Links
Acutance and SQF (Subjective Quality Factor): perceptual sharpness measurement
Introduction – Acutance and MTF – Meaning of Acutance & SQF – Measuring Acutance & SQF – The SQF equation – CSF – Links
Other Image Quality Factors
Introduction – Appearance – Noise measurements – Noise summary – F-stop noise – The mathematics of noise – Links
Temporal Noise – comparing the two-image and multi-image measurements
Nyquist frequency, aliasing, and Color Moire – introducing a color aliasing metric derived from hyperbolic wedges.
Dynamic Range – a general introduction with links to Imatest modules that calculate it.
Sensor vs. System DR – DR definitions – Transmissive chart – Lightbox – Measuring DR – Contrast Resolution chart – Tips – More on Flare – F-stop noise & scene-referenced SNR
Chromatic Aberration – (Lateral Chromatic Aberration) AKA Color fringing
Introduction – Target – Stepchart measurement – Results – ISO 9358 – ISO 18844 measurements with Uniformity
Introduction – Incident light measurement – Modules – Equations – RAW files – Saturation-Based – Standard Output – Related documents
Shannon information capacity – information that can pass through a channel without error
Image quality utilities let you degrade, enhance, examine, and perform simple analyses of any image (not just test charts)
Image Processing – Simulate several image processing operations (degradations: blur and noise; enhancements: sharpen, bilateral filter, tone mapping, etc.) and observe their effects on appearance and measurements (MTF, SSIM, etc.).
Operation – Image processing blocks – Displays and analysis – Optical Character Recognition (OCR) – Face and People Detection
SSIM: Structural Similarity Index – Measure image quality degradation and artifacts from signal processing such as compression. Also, measure PSNR.
Image Statistics – Interactively observe image statistics: cross sections, means, noise, SNR, histograms, and frequency spectra.
Radial Geometry – Add or correct distortion, lateral chromatic aberration, or rotation to images.
Getting Started with Image Quality Testing
Why Imatest? | Test Charts | Lighting | Image Capture Technique | Setting up Your Lab | Using Imatest Software
Start Using Imatest Software
Installation – and getting started
Using Imatest – Introduction and general instructions
Running Imatest – Multi file read – RAW files – Other controls – Options I – Options II – EXIF data & ExifTool – Dropdown menus – Figures – .CSV and JSON output – Use of Imatest
Activation/Deactivation – Activating Imatest and moving it from one computer to another
Online Activation | Offline Activation | Online Deactivation | Offline Deactivation | Floating Licenses | Proxy Server
Knowledge base — contains several links to help solve activation issues.
| Please note: Each Imatest license can be activated on only one computer at a time, but the activation can be easily moved between computers, especially if they’re online. You can install Imatest– and keep it installed– on as many computers as you like (Macintosh as well as Windows– your license works for both; you never have to uninstall it). To move the activation to another computer, you’ll need to deactivate it on the old computer then activate it on the new one, following the instructions above. You may do this as often as you like. |
Imatest Instructions – general
Session Logging – Log level controls for display and log files
Skype video specification support – Instructions and suggestions
Android Camera Interface for direct image acquisition
Sony AYA Interface for direct image acquisition
Sony AYA Interface for direct image acquisition
Autobatch – Combine several test images (from different modules) for a single device into an automatic batch run.
The Imatest Functional Interface – A simplified interface for running tests with consistent settings
Introduction – Using RAW files – Bayer RAW and RCCC files – dcraw demosaicing – DNG files – Rawview utility – Generalized Read Raw – Decompanding – Creating synthetic raw images
Building a test lab – How to build a testing lab
Introduction – Hardware – Building a Low-Cost Test Lab – Easel – Light measurement – Tripod – Clamps – Putting it together – Targets – Aligning target & camera
Saved settings – Imatest.ini and INI files for use with Imatest IT
Pass/Fail Monitor – Realtime display and update of pass/fail results (useful with Imatest IT)
Troubleshooting – What to do when Imatest doesn’t work
Installation problems – Version 3.6+ changes – Problems after install – Missing DLLs – Runtime problems – Corrupted INI file – A module has stopped working – Error reporting – Command (DOS) window – Diagnostics runs – Path conflicts
Knowledge Base highlights – Links to articles for troubleshooting, activation, and general advice on operation.
There are many more links like these on the Knowledge Base.
Sharpness modules
SFR – Basic analysis of slanted-edges (manual ROI selection)
Using SFR Part 1 – Setting up and photographing SFR targetsUsing SFR Part 2 – Running Imatest SFR
Image file – ROI – Cropping recommendations – Additional input – Equations – Gamma – Warnings – Saving – Repeated runs – Excel CSV output
SFR results: – Chromatic Aberration, Noise, and Shannon capacity plot
| Feature | SFRplus |
eSFR ISO |
SFRreg |
Checkerboard |
| Sharpness map detail | High | Medium | Depends on arrangement | High |
| ISO-standard chart design | – | ♦ | – | – |
| Color analysis | ♦ | ♦ | * | – |
| Tonal response (OECF) | ♦ | ♦ | * | – |
| Noise analysis | Limited | ♦ | * Limited | Limited |
| Distortion | ♦ | Limited | – | ♦ |
| Geometry | ♦ | ♦ | * | ♦ |
| Features and recommended uses |
Imatest’s original automatically-detected chart, in use since 2009. robust and versatile. Some white space recommended above and below top and bottom bars. More spatial and distortion detail than eSFR ISO. |
ISO-standard chart design. Includes wedge analysis. Supports detailed noise analysis. |
Several individual charts are typically placed around the image field. Works with *FoV is omitted from geometry. |
Relatively insensitive to framing: can zoom in or out as long as distance is large enough so chart quality is not an issue and there are detectable corners. Well-suited for through-focus measurements. Very accurate distortion measurements. |
♦ denotes strong support; – denotes no support.
SFRplus – Automated analysis of slanted-edges
Using SFRplus Part 1 – The SFRplus chart: features and how to photograph itSlanted-edge test – Advantages – Obtain chart – Framing – No bars – Lighting – Distance – Exposure – Tips – Links
Using SFRplus Part 2 – Running SFRplus
Selecting files – Setup window – ROI selection & analysis area – Edge ID Files – More settings window – Settings area – Auto mode window – Warnings – Summary
Using SFRplus Part 3 – SFRplus edge results
Multi-ROI summary – Edge and MTF – Chromatic Aberration – Acutance/SQF – Histograms & noise – Image, Geometry, Distortion, FoV – 3D Plots – Lens style MTF plot – Edge roughness – Point Spread Function – Summary – CSV & JSON output
Rescharts Slanted-edge results Part 4 – SFRplus other results (tones, color, distortion, etc.)
Pre-distorted and special charts for Fisheye Lenses – with many applications such as automotive rear view cameras Includes SFRplus, eSFR ISO, and SFRreg charts. Previewing pre-distortion
Introduction – Pre-distorted charts – Running SFRplus & Algorithm – Results – Distortion correction display – Radial plot
Introduction – Test chart – Photograph – Lighting – Run SFRplus – Rescharts SFRplus – SFRplus settings – Auto run options – Display options – Secondary readout – Interpret the results – Batches – Checklist – Links
eSFR ISO – Automated analysis of the ISO 12233:2014 Edge SFR chart
Using eSFR ISO Part 1 – The ISO 12233:2014 E-SFR chart: features and how to photograph it
Slanted-edge test – ISO 12233:2014 compliance – Advantages – Obtain chart – Framing – Lighting – Distance – Exposure – Tips – Links
Using eSFR ISO Part 2 – Running eSFR ISO
Multi-ROI summary – Edge and MTF – Chromatic Aberration – Acutance/SQF – Histograms & noise – Image, Geometry, Distortion, FoV – 3D Plots – Lens style MTF plot – Edge roughness – Point Spread Function – Summary – CSV & JSON output
Rescharts Slanted-edge results Part 4 – eSFR ISO other results (tones, color, wedge, etc.)
SFRreg – Automated analysis of registration mark patterns
- Test at infinity focus with Long Range projection systems
- Test imaging systems with ultrawide fisheye lenses (>180 degrees)
- Test at very long camera-to-chart distances
- Test at variable distances for Depth of Field.
Using SFRreg Part 1 – Registration mark patterns and how to photograph them
target projection – Chart arrays for fisheye lenses – Center Chart – Obtain and photograph chart – Lighting – Distance – Exposure – Tips – Links
Using SFRreg Part 2 – Running SFRreg
Using SFRreg Part 3 – SFRreg edge results
Multi-ROI summary – Edge and MTF – Chromatic Aberration – Acutance/SQF – Histograms & noise – Image, Geometry, Distortion, FoV – 3D Plots – Lens style MTF plot – Edge roughness – Point Spread Function – Summary – CSV & JSON output
Rescharts Slanted-edge results Part 4 – SFRreg other results (tones, color, distortion, etc.)
Checkerboard – Automated analysis of checkerboard patterns
Using Checkerboard Part 2 – Running Checkerboard
Selecting files – Setup window – ROI selection & analysis area – Edge ID Files – More settings window – Settings area – Auto mode window – Warnings – Summary
Using Checkerboard Part 3 – Checkerboard edge results
Multi-ROI summary – Edge and MTF – Chromatic Aberration – Acutance/SQF – Histograms & noise – Image, Geometry, Distortion, FoV – 3D Plots – Lens style MTF plot – Edge roughness – Point Spread Function – Summary – CSV & JSON output
Rescharts Slanted-edge results Part 4 – Checkerboard other results (distortion, etc.)
Rescharts modules – Log F-Contrast, Star, Random, Wedge
Using Rescharts – Analysis of resolution-related charts
Introduction – Getting started – The Rescharts window – Rescharts modules – Slanted-edge SFR – SFRplus – Log frequency (simple) – Log frequency-contrast – Star – Wedge – Random/Dead Leaves – Focus ScoreLog Frequency – Analysis of log frequency-varying charts
Introduction – Photographing, running – Color moire – Output – Pattern – MTF – Comparisons – Calculation details – Nyquist, aliasing
Log F-Contrast – Analysis of charts that vary in log frequency and contrast
Introduction – Creating, printing – Photographing, running – Output – Pattern – MTF – MTF/contrast contours – MTFnn
Sharpness and Texture Analysis using Log F‑Contrast from Imaging-Resource – comparing of several different cameras.
Star Chart – Analysis of the Siemens star chart
Introduction – Creating, photographing, running – Output – MTF – MTFnn, MTFnnP – MTF contours – Equations
Random/Dead Leaves – Scale-invariant test charts (including Imatest Spilled Coins)for measuring texture sharpness
Introduction – Creating, photographing, running – Automatic ROI detection – Output – MTF – MTFnn, MTFnnP – Power Spectral Density – Equations
Texture examples – More details of Imatest Spilled Coins texture sharpness measurements
Dead Leaves measurement issue – Illustrates challenges posed by extreme signal processing
Wedge Analysis – Analysis of hyperbolic or trapezoidal wedge patterns with the Wedge and eSFR ISO modules
Introduction – Recommendations – Instructions – Results – Stability – Limitations & Comparisons – Calculation details – MTF/Nyquist & Aliasing
Sharpness utilities & postprocessors
MTF Compare – Compare MTFs of different cameras and lenses
Image Stabilization/Sharpness Compare – SFRplus postprocessor for analyzing (Optical) Image Stabilization
and comparing sharpness of different images
and comparing sharpness of different images
Batchview – Postprocessor for viewing summaries of SFR, SFRplus results
Find Sharpest Files – Find the sharpest files in a batch
Tone, color, and spatial modules
Tone, Color, Noise, and Dynamic Range
Introduction – Getting started – Supported charts – Reference files – The Color/Tone Setup window – Displays and options
Using Color/Tone Auto (Multitest) – Fixed (batch-capable) analysis of color & grayscale test charts
Color/Tone/eSFR ISO Noise – including chroma, sensor (RAW), and visual noise
Chroma noise – Imatest Dynamic range – Image sensor (raw) noise and Dynamic Range – Temporal noise – ISO 15739 & CPIQ Visual Noise – ISO 15739 SNR and Dynamic Range – f-stop noise & scene-referenced SNR
Contast Detetction Probability (CDP) – Based on IEEE p2020 automotive image quality standard
Color/Tone Special Charts – Additional charts, including ISO OECF and noise chats and circles arranged on a square
Color Correction Matrix (CCM) Calculate a matrix (usually 3×3) for correcting image colors (often from RAW images)
Introduction – Math – Calculating in Color/Tone Setup – Saturation – Applying the matrix 1. in Color/Tone 2. in Image Processing 3. externally with program code
Nonuniformity Correction in grayscale and color chart modules for Color/Tone Auto or Setup, Stepchart, and Colorcheck
Dynamic Range – a general introduction with links to Imatest modules that calculate it.
Contrast Resolution – A special transmissive chart for measuring the visibility of low contrast features in larger fields over a wide dynamic range. Analyzed with Color/Tone Interactive or Auto.
What Colorcheck does – Colorchecker colors – Photographing target – Running Colorcheck – Colorchecker reference sources – Output – Temporal noise – Auto-white balance – Saving – Links
Colorcheck/Color/Tone Appendix – Color difference algorithms and reference formulas
Color difference formulas – Color ellipses (Delta-C ab, Delta-C 94, Delta-C 2000, etc.) – Color difference visualizer – Chroma correction (corr) – Algorithm – Grayscale and Exposure error
Photographing the chart – Running Stepchart – Output – Temporal noise – Auto-exposure – Saving – Dynamic range – Algorithm
Dynamic Range (postprocessor) – Calculate Dynamic Range from several Color/Tone Auto or Stepchart images
Measuring test chart patches – with a Spectrophotometer and one of two software packages
Spatial and Uniformity modules
Using Uniformity, Part 1Using Uniformity, Part 2 – Features in Imatest Master and IS (not in Studio)
Input dialog box – Hot and dead pixels – Color shading – Uniformity profiles – Grid plot – Polynomial fit – Histograms – Noise detail – Spot detection
Using Uniformity-Interactive – Interactive measurement of vignetting and sensor nonuniformity (can be used with direct image acquisition)
Using Blemish Detect – Measure visible sensor defects
Lightbox Comparison Guide – Comparing lightbox brightness and uniformity
Testing flat screen displays – with Imatest Blemish Detect
Using Distortion (Checkerboard is recommended for strongly barrel-distorted (“fisheye”) lenses.)
Introduction – Instructions – Results – Main figure – Decentering – Corrected image – Intersection figure – Radius correction fig – Comparison with other modules – Links – Algorithm
Dot Pattern – Analysis of a grid of circular dots
Miscellaneous modules and utilities
Arbitrary Charts – Analyze a chart layout you have designed yourself.
Using Test Charts – Create test charts for high quality inkjet printers
SVG Test Charts – Scalable Vector Graphics charts for MTF and other measurements
Introduction: m x n squares – Squares and wedges – USAF 1951 chart – Operation – Options – Output figure – Printing
Using Screen Patterns – Monitor patterns for Light Falloff, SFR, Distortion, and monitor calibration
Introduction – Light Falloff – SFR – Distortion – Monitor calibration – Monitor gamma – Zone plate – SMPTE color bars – Slanted edges – Colorchecker-Stepchart – Squares (checkerboard)
Rename Files – using EXIF data
Image Processing – Simulate several image processing operations (degradations: blur and noise; enhancements: sharpen, bilateral filter, tone mapping, etc.) and observe their effects on appearance and measurements (MTF, SSIM, etc.).
Image Statistics – Interactively observe image statistics: cross sections, means, noise, SNR, histograms, and frequency spectra.
Composite Chart – Create a synthetic test chart from several individual image files.
Educational Apps – Learning resource for image quality factors and measurements.
Imatest IT – Industrial Testing (non-GUI)
Imatest IT-EXE instructions – Running Imatest IT (Industrial Testing)-EXE
Introduction – Installation – Step 1: Capture Images – Step 2: Configure INI File – Step 3: Call Imatest IT Modules – Step 4: Process Results – Error Handling – Sample Code – Advanced Topics – Troubleshooting
Imatest IT-C instructions – Running Imatest IT (Industrial Testing)-C
Introduction – Installation – Step 1: Capture Images – Step 2: Configure INI File – Step 3: Call Imatest IT Modules – Step 4: Process Results – Error Handling – Sample Code – Advanced Topics – Troubleshooting
Imatest IT-C++ instructions – Running Imatest IT (Industrial Testing)-C++
Introduction – Installation – Step 1: Capture Images – Step 2: Configure INI File – Step 3: Call Imatest IT Modules – Step 4: Process Results – Error Handling – Sample Code – Advanced Topics – Troubleshooting
Imatest IT-Python instructions – Running Imatest IT (Industrial Testing)-Python
Introduction – Installation – Step 1: Capture Images – Step 2: Configure INI File – Step 3: Call Imatest IT Modules – Step 4: Process Results – Error Handling – Sample Code – Advanced Topics – Troubleshooting
Imatest IT-.NET (C#) instructions – Running Imatest IT (Industrial Testing)-.NET (C#)
Introduction – Installation – Step 1: Capture Images – Step 2: Configure INI File – Step 3: Call Imatest IT Modules – Step 4: Process Results – Error Handling – Sample Code – Advanced Topics – Troubleshooting
Imatest IT-.NET (Visual Basic) instructions – Running Imatest IT (Industrial Testing)-.NET (Visual Basic)
Introduction – Installation – Step 1: Capture Images – Step 2: Configure INI File – Step 3: Call Imatest IT Modules – Step 4: Process Results – Error Handling – Sample Code – Advanced Topics – Troubleshooting
Imatest IT Parallel (IT-P) – Accelerating Imatest IT by performing tests in parallel
Imatest INI file reference – Reference to INI files for IT/EXE and IT/DLL users (sections used in several modules)
Direct Read Mode – Pass image data directly into Imatest IT, without writing to a file on disk
Implementing Pass/Fail – Setting up Pass/Fail criteria and Pass/Fail Reference. For Imatest IT and GUI versions.
Pass/Fail Monitor – Realtime display and update of pass/fail results (useful with Imatest IT)
Operator Console – User interface for production environments
Imatest IT Knowledge Base – Articles about Imatest IT
Appendix
FAQ – Frequently Asked Questions
Cross-reference tables – Tables to help you navigate Imatest
Version comparison: Studio vs. Master – Which is right for you?
Troubleshooting – What to do when Imatest doesn’t work
Installation problems – Problems after install – Missing DLLs – Runtime problems – Corrupted INI file – Command (DOS) window – A module has stopped working – Diagnostics runs – Path conflicts
Imatest Change Log – Imatest release history
Default INI Folder – Location on your computer of resource files used by Imatest
License – The Imatest End User License Agreement (EULA)