Tables to help you navigate Imatest modules and charts Imatest is a complex, rich application involving a great many image quality factors, modules, and test charts. The tables below, for Quality Factor, Module, and Test chart are designed to help navigate the site. A Table of contents is also available. Image quality factors – Modules – Test charts – Test images  Algorithms – Suppliers Image quality factors Image quality factors have their own page. A brief list of recommended test charts is given in the FAQ. Quality factor Charts Module Comments Camera, lens Color accuracy X-Rite ColorChecker (24-patch) Colorcheck, Color/Tone […]

Related pages Dynamic Range  a comprehensive introduction: strongly affected by flare light. Veiling glare (lens flare)  describes several measurement techniques, including the new Contrast Resolution method. Making Dynamic Range Measurements Robust Against Flare Light   Introduction Introduction – Background – The Contrast Resolution chart – Photographing & analyzing – Tonal response and SNR – Visualization – Visual analysis – Contrast Resolution Dynamic Range – Tone mapped results – Flare Mask & two-image measurement – Summary – Verification – References  This page describes the Imatest Contrast Resolution chart and analysis (supported by Imatest 5.0+), which is designed to measure the visibility of low […]

including raw (image sensor), chroma, and visual noise as well as several types of Dynamic Range calculation News– 2021: Using images of noise to estimate image processing behavior for image quality evaluation  was presented at Electronic Imaging 2021. Noise can be measured anywhere in an image– on edges, etc.– if multiple identical images are acquired. This will lead to some interesting applications. Imatest 5.2: Multicharts (the highly interactive module for measuring color accuracy, tonal response, and noise) has been renamed to Color/Tone Setup, and Multitest (the fixed/batch-capable version of Multicharts) has been renamed to Color/Tone Auto. For now the old […]

Introduction  |  Measurement  |  Modules  |  Demosaicing Purple fringing – CA correction for non-tangential edges Introduction Chromatic aberration (CA) is one of several aberrations that degrade lens performance. (Others include coma, astigmatism, spherical aberration, and curvature of field.) It occurs because the index of refraction of glass varies with the wavelength of light, i.e., glass bends different colors by different amounts. This phenomenon is called dispersion. It appears as color fringing, most visibly on tangential edges near the boundaries of the image. It is sometimes confused with another effect, which we call pixel shift— a color channel offset that is […]

Obtain and photograph chart –  Lighting – Distance – Exposure – Tips – Links Imatest Checkerboard performs highly automated measurements of sharpness (expressed as Spatial Frequency Response (SFR), Lateral Chromatic Aberration, and optical distortion from images of checkerboard patterns (with a recommended tilt angle of ~5-8 degrees for sharpness measurements). The primary advantages of Checkerboard are: Compared to Imatest’s other automatically-detected sharpness modules:  It is relatively insensitive to framing. You can zoom in or out as much as you like, as long as there are detectable corner features.  Compared to the Distortion (legacy) module:  It works with highly-distorted (fisheye lens) images. Calculations are more accurate, and it contains all results […]

For more information on how to use INI files in Imatest IT, we recommend the Imatest INI File Reference This document was created by running checkerboard in Imatest 5.2.0. ALPHA on 30-May-2019 22:57:20. For Imatest IT, most of these entries don’t need to be entered. Many don’t affect Imatest IT results: they control interactive figure displays or figure output formats (figures are often not used in Imatest IT). Background Meaning Yellow Yellow background: Important to Imatest IT. Parameter and Description are in boldface. [IT] Cyan Cyan background: Figure settings. (Figures are used infrequently for IT.) [f] Gray Gray background: For […]

Imatest 5.1 has important new capabilities for measuring and correcting MTF degradation caused by test charts. These new capabilities are far easier to understand and apply than CQI. Chart quality calculator Compensating camera MTF measurements for chart and sensor MTF As a result of the improved measurements, the Chart Quality Index measurement has been deprecated. The Chart Finder is an interactive web page that can help you select the appropriate chart size and media. It contains results from this page, but without the math. Summary In order to determine the suitability of a test chart is for measuring the performance of a […]

Imatest lets you use the measured test chart modulation transfer function (MTF) to Determine the suitability of a test chart, which is characterized by size (height), print media, and printing technology, for camera MTF measurements where the camera is characterized by the number of vertical pixels. This can help determine whether a test chart is appropriate for a specific application.  Increase the accuracy of MTF measurements by dividing the measured camera MTF by the chart MTF projected on the image sensor. This is equivalent to deconvolution in spatial domain. This technique is described in Compensating camera MTF measurements for chart and […]

Postprocessor for viewing summaries of SFR, SFRplus, Checkerboard, and eSFR ISO results Introduction to Batchview Batchview is a postprocessor for displaying lens test results generated by SFR, SFRplus, and eSFR ISO batch runs (analyses of groups of test chart images taken at various apertures, focal lengths, etc.). It can store and display up to four sets of results for convenient comparisons in Imatest Master; two in Studio. Postprocessor comparison Each lets you compare sharpness of different regions and/or images MTF Compare Postprocessor to SFR, SFRplus, and eSFR ISO. Input is two CSV results files for individual regions. Lets you compare individual […]

Imatest 4.4+ can evaluate auto-focus (AF) as a measure of MTF with respect to time. This can be performed by using the SFR module with an appropriate video file. Related pages Auto Exposure in Stepchart Autofocus Speed in SFR Auto White balance in Colorcheck Uses/Purpose This metric is intended to be used as a way to measure the time a camera system takes to auto-focus. Rise time and settling time are automatically calculated. This measurement does not provide information about the accuracy or precision of auto-focus. To evaluate those measures, several measurements should be performed on the final, settled images and compared. File […]

Analyses & Output – INI settings – Chart Definition Files – Chart Definition Utility   INI file fields relevant to Arbitrary Charts The following INI fields are currently exposed to the user to control the behavior of the Arbitrary Charts module and its output. They have been organized here by topic, but do not need to be in any particular order or grouping in your INI file itself.    [arbcharts] section Slanted-edge Analysis     Texture Analysis   Star Analysis   Wedge Analysis   Uniformity Grid Analysis   Color/Tone/Noise   Perceptual metrics   Module operation and misc.   [api] section   […]

Analyses & Output – INI settings – Chart Definition Files – Chart Definition Utility   Data outputs from the Arbitrary Charts Module are different from other modules in Imatest: Only JSON files are output, not CSV or XML. The structure of JSON is substantially different than other modules.  If several images are run in a batch, results from all images may be contained in a single JSON. Since the Arbitrary Charts Module is based on the concept of a custom layout of features, there is no fixed structure to the measurement results that the Module produces. Instead, the module simply produces […]

Analyses & Output – INI settings – Chart Definition Files – Chart Definition Utility   Combine all the features you need to analyze into a single chart Introduction The Imatest™ Arbitrary Charts module analyzes images of custom test charts. A chart-definition file (typically user defined) is needed to describe the chart layout to Imatest software. The Arbitrary Charts module will automatically locate and analyze target features when an observed image of a chart is loaded along with the corresponding definition file.    This module allows users to get a number of measurements out of custom, legacy, or competitors’ charts which are unsupported […]

Introduction to Acutance and SQF   Acutance and Subjective Quality Factor (SQF) are measures of perceived print or display sharpness. SQF was used for years in the photographic industry but has remained unfamiliar to most photographers. Acutance is a relatively new measurement from the IEEE Camera Phone Image Quality (CPIQ) group. Both are metrics which incorporate the effects of The imaging system: The Modulation Transfer Function (MTF) of the camera as a measurement of its intrinsic sharpness. The viewer: The human eye’s sensitivity to each spatial frequency modeled with a Contrast Sensitivity Function (CSF). The viewing conditions: The image display height […]

Introduction Watch on YouTube. Imatest IT (Industrial Testing) is a set of Application Programming Interfaces (APIs) that allow developers to access Imatest’s powerful image quality analysis tools in their own custom applications. Imatest IT is available for 64-bit Windows, MacOS and Linux, and includes libraries for use with C, C++, Python, Objective-C, .NET (Windows only – including C# and Visual Basic), and LabVIEW. IT also contains standalone executables that can be called from a command line or script. The API libraries perform the exact same calculations as the corresponding GUI-based Imatest Master modules. Imatest IT is a complete package that […]

Imatest 4.5+   The Checkerboard Module is strongly recommended for distortion measurements because its corner detection algorithm is much more accurate and it is tolerant of large amounts of optical distortion, which can cause the Distortion module to fail. Checkerboard, which calculates distortion, MTF, and lateral chromatic aberration is Imatest’s primary recommended means of calculating optical distortion. The Distortion module will be removed after the 22.2 release and is not recommended for new work. If you are using it, we recommend avoiding the grid (line) pattern because it is much fussier than the checkerboard: thin lines may fail to be detected; thick lines reduce […]

Table of Contents Intro to stray light (flare) How to test for stray light Setting up for stray light testing Physical set up and alignment Test environment Test coverage: extent and sampling Image data Imatest’s hardware solution for stray light testing Imatest Motorized Gimbal Broadband Halogen Fiber Optic Illuminator (Benchtop Setup)  Imatest configurable light source Imatest Motorized Test Stand Imatest Blackout Curtain Fixture   Intro to Stray Light (Flare) What is stray light and how is it measured? Stray light, also known as flare, is any light that reaches the detector (i.e., the image sensor) other than through the designed […]

Postprocessor for SFRplus, Checkerboard, and eSFR ISO for analyzing image quality factors that require multiple images: Curvature of field, Longitudinal (Axial) Chromatic Aberration, & more Introduction to FocusField FocusField is a postprocessor for displaying camera test results from batches of images acquired at different distances and/or with different focus settings (also with different apertures), then analyzed by SFRplus, Checkerboard, or eSFR ISO  batch runs. (These modules are preferred because magnification, and hence distance, can be derived from the image.) It can display Depth of Field (DoF), Curvature of field, Longitudinal (axial) chromatic aberration, and Lens focal length (when used with the motorized […]

Analysis of wedge patterns with the  Imatest Wedge and eSFR ISO modules News  2021.2 —  Logarithmic wedges: a superior design describes the advantages of logarithmic wedges, which have a much better distribution of spatial frequencies than hyperbolic wedges, allowing a larger maximum/minimum frequency ratio. Supported by Imatest (automatically detected) since 2021, but (as of May 2022) not currently included in standard eSFR ISO charts (though available on request).  2020.2 —  Calculations were greatly sped up in order to improve performance of direct image acquisition. During the testing of the speedup with direct acquisition, we found that Wedge results were unstable during […]