Introduction Part 1 of this page illustrates images analyzed in Random Scale-invariant & Dead Leaves. The images are not shown original size; they’ve been resized to be approximately equal in magnification with respect to the original chart image— with enough magnification to show the results of the camera optics and image processing. Part 2 demonstrates how demosaicing is the cause of a commonly observed discrepancy between Spilled Coins and slanted-edge MTF measurements. Part 1: Images used in Random / Dead Leaves Original pattern (cropped from the middle of the chart), for reference. Original pattern (reduced from file used to print […]

These posts describe several topics, including: SFRplus Quadrant analysis (it includes the center region as well), Saturation analysis, which attempts to estimate the severity of saturation in slanted-edge regions (ROIs), and a few other recent additions (November 2012). Saturation is important because saturated light or dark regions will result in artificially high MTF readings. How to select regions at a fixed distance from center to corner (typically in the range of 65-85%)

Introduction The Imatest Image Stabilization/Sharpness Compare module is a postprocessor for SFRplus that Measures the effectiveness of Optical Image Stabilization (abbreviated as IS or OIS) by comparing the sharpness (MTF or related lengths) of selected near-horizontal and near-vertical edges from three similar SFRplus images: Unshaken. Shaken without Image Stabilization. (Some recent cameras lack the ability to turn IS off. There are several approaches to measuring IS effectiveness in this case. One is to have a very precise vibratory apparatus with known vibration angles. Expen$ive. Another is to substitute a camera with similar pixel configuration and lens focal length, but no […]

Gamma is the exponent of the equation that relates scene luminance with image pixel level. When the raw output of the image sensor, which is linear, is converted to image file pixels for a standard color space, the equation below is applied (very approximately, as we’ll explain below). pixel level = (RAW pixel level)gamma_camera ~= exposuregamma_camera      (1) When an image file is sent to a display (a monitor or print), Output luminance = (pixel level)gamma_display      (2) The total system gamma is gamma_camera * gamma_display.  Standard values of display gamma are 1.8 for older color spaces used in the Macintosh and 2.2 […]

Since SFRplus (and eventually eSFR ISO, which uses almost all the same settings) is included in IT EXE and DLL, users may sometimes need to examine or edit the INI file used to control IT versions. Most of the settings in the [sfrplus] or [esfriso] section are set by one of the three SFRplus or eSFR ISO Settings windows that can be opened when SFRplus is run in Rescharts (or by clicking SFRplus setup in the Imatest main window). A few are set by responses to other windows or user actions. Settings that affect only Rescharts mode (and hence do […]

Instructions and comments We are updating this page for the latest Skype/Lync specification. An index of of the Skype/Lync specifications can be found on  http://technet.microsoft.com/en-us/lync/gg278181.aspx. This document contains instructions for using Imatest with the Skype Hardware Certification Specification — For all Skype Video Devices Version 5.0. It also contains comments and suggestions (some of which we hope might be adopted in a future release of the spec). The Skype spec uses only a tiny fraction of Imatest’s powerful capabilities. To learn more, see Image Quality Factors and SFRplus (which allows many factors to be measured from a single image). In […]

How Imatest IT/DLL works Imatest IT/DLL (Industrial Testing DLL; formerly API/DLL) is a library that allows developers to access Imatest‘s powerful image quality analysis tools via calls to functions residing in a Dynamic Link Library. At the present time (in Imatest 4.4) it supports calls from C and C++ , .NET (including C# and VB.NET), and Python.  Support for LabVIEW is under development. DLL modules perform the same calculations as the corresponding GUI-based Imatest Master modules. Fifteen modules are available: SFR   SFRplus   Star   OIS Colorcheck   Stepchart   Wedge   Random Uniformity (Light Falloff)   Distortion   eSFR ISO   SFRreg […]

Imatest Pass/Fail Operation and Reference Introduction Imatest can return pass/fail (P/F) results for industrial inspection or for any tests where pass/fail results are required. Although pass/fail is primarily intended for IT (DLL and EXE), it works with GUI-based versions of Imatest (except for Studio), where it can be particularly useful for testing P/F thresholds for Imatest IT. Starting with Imatest 4.0, the Pass/Fail monitor lets you examine P/F results in detail. Getting started – Summary – Pass/fail settings file – Pass/Fail Reference Slanted-edge (SFRplus, etc.) settings Blemish and Uniformity settings Getting started with Pass/Fail Determine the measurements to use for […]

This page is a reference for the INI files used to store Imatest settings, particularly imatest-v2.ini, which is the basis of ini files used to control Imatest IT. It focuses on INI file settings that are used by several modules and are of interest to users of Imatest IT and the Functional Interface.  INI file structure – Extracting an INI file for IT – Running from a Custom File – INI File Monitor – [api] (for Imatest IT) [dcraw] – [rdraw] (Generalized Read Raw) – Secondary Readouts – Miscellaneous To keep this document to a reasonable length, the INI references for Imatest IT modules are stored […]

Find the sharpest files in a batch Thanks for Andrea Nivini for suggesting this module. New in Imatest 5.2: A major redesign of Find Sharp Files. A summary plot is available. Results can be shown in an easy-to-read Table format. Results can be saved in CSV and JSON files.   Find Sharpest Files lets you quickly and conveniently rank the sharpness of a set of images. It works on any image— it doesn’t have to be a test chart. It runs much faster than any of the standardized sharpness measurements (slanted-edge, star, etc.). There are a number of situations where this capability […]

Postprocessor for viewing summaries of SFR, SFRplus 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 edges from any region […]

Analysis of hyperbolic or trapezoidal wedge patterns with the Imatest Wedge and eSFR ISO modules Introduction Imatest Master and IS can analyze wedge patterns in two modules, both of which may be run from the interactive Rescharts interface or as fixed (batch-capable) modules. The Wedge module (described in this document) can analyze any arrangement of horizontal or vertical (but not diagonal) wedges, using manual region selection. The eSFR ISO module can analyze pairs of wedges on the Enhanced and Extended eSFR ISO charts (including the charts with extra wedges), introduced in April 2014. Region detection is fully automated. The user […]

Testing lenses: Introduction Lens quality (especially sharpness) has always been of great interest to photographers. It’s what we spend the big bucks for— if we have them. And it’s what we look for in a lens at any price point. Traditionally, lens testing has been highly tedious, best left to professionals and large publications. With Imatest, that has changed forever. All you need to do is photograph an SFRplus, ISO-12233:2014+ eSFR, or tilted checkerboard chart (with careful technique of course), run SFRplus or eSFR ISO, and interpret the results. This page contains the recommended procedure for testing lenses using Imatest […]

Running SFRplus (Interactive and Auto mode settings) Imatest SFRplus performs highly automated measurements of several key image quality factors using a specially-designed test chart. This document shows how to run SFRplus in Rescharts and how to save settings for automated runs. Part 1 introduced SFRplus and explained how to obtain and photograph the chart. Part 3 illustrates the results. New in Imatest 3.10 SFRplus settings can be updated by clicking Settings, SFRplus Auto settings in the Imatest main window without having to read an image file into Rescharts SFRplus Setup. New in Imatest 3.9 SFRplus can be run without including […]

Imatest SFRplus results Imatest SFRplus performs highly automated measurements of several key image quality factors using the specially-designed SFRplus test chart. Unlike most other modules, the user never has to manually select Regions of Interest (ROIs). Image quality factors include Sharpness, expressed as Spatial Frequency Response (SFR), also known as the Modulation Transfer Function (MTF), Noise, Lateral Chromatic Aberration, Distortion (with nearly as detailed output as the Distortion module). Described in detail here. Tonal response (again, with less detail than Stepchart; no noise statistics) Color accuracy, when used with an SFRplus that contains the optional color pattern, located above the […]

Analysis of Log Frequency-Contrast charts New in Imatest 4.0  Automatic region is available with the revised version of the chart, which includes registration marks in the corners. Sharpness and Texture Analysis using Log F‑Contrast from Imaging-Resource compares the the effects of sharpening and noise reduction in several cameras using images downloaded from Imaging-Resource.com. Introduction Log F-Contrast (short for Log Frequency-Contrast; not in Imatest Studio) measures the effects of signal processing— noise reduction and sharpening— on imaging system performance using a chart that varies in spatial frequency on the horizontal axis (log frequency increases with x) and in modulation (i.e., contrast) […]

Analysis of random scale-invariant patterns, including the Spilled Coins (Dead Leaves) Pattern, for measuring texture sharpness Introduction – Obtaining – Photographing – Running – Automatic ROI detection – Output  MTF – MTFnn, MTFnnP – Power Spectral Density – Equations & Scale-invariance   Introduction  Random/Dead Leaves, which runs under the interactive Rescharts interface or as a fixed (non-interactive, batch-capable) module, measures SFR (Spatial Frequency Response) or MTF (Modulation Transfer Function) from random scale-invariant (or approximately scale-invariant) test charts, including “Dead Leaves” and “Spilled Coins” charts. It is primarily used to measure the effects of signal processing on image texture. Dead leaves/Spilled Coins charts are of increasing interest because their statistics resemble those of natural […]

Analysis of log frequency-varying charts Introduction Log frequency, which uses the Rescharts interface, measures the contrast of narrow bar or sine charts that increase logarithmically in spatial frequency. It also measures color Moiré (Imatest Master only). When the image pattern is sinusoidal (rather than a bar chart), contrast is equivalent to SFR or MTF. This method is more direct than the slanted-edge method, but less accurate and more susceptible to noise. A chart can be created by Test Charts and printed on a high quality inkjet printer. Log Frequency image (complete and cropped) The image above used to illustrate the […]

Measure visible sensor defects The Human Visual System – Algorithm – Instructions – Settings window – Filtering and threshold – Display options – Defective pixels – Tuning – Results Blemish Detect detects visible sensor defects (typically blurred (dark) spots caused by dust in front of the image sensor, but light blemishes can also be detected). To ensure that only visible blemishes are flagged— and blemishes below the threshold of visibility are not— the image is filtered by a response function derived from the Human Visual System (HVS). Filter settings are adjustable for a wide range of applications and viewing conditions. Blemish detect also includes all […]

Monitor patterns for Light Falloff, SFR, Distortion, and monitor calibration Introduction Screen Patterns displays a variety of test patterns on monitors, preferably on LCD flat screen monitors. It may become more useful as cost-effective ultra-high resolution (4k+) monitors become available. It is opened by clicking on Screen Patterns on the right of the Imatest main window. Most patterns (except perhaps Monitor calibration) perform best with the window maximized. You may need to redraw the pattern after maximizing (or resizing) it by selecting the pattern or changing one of the settings. These patterns are offered as a convenient alternative to the […]