A comparison of sensitivity to signal processing: Results for additional cameras This page contains additional Slanted-edge, Siemens Star, and Log F-Contrast results for four cameras, in support of claims in Slanted-edge versus Siemens Star that Siemens Star MTF measurements are nearly as sensitive to sharpening as low-contrast (4:1) slanted-edge measurements. The Siemens Star’s high contrast (specified at >50:1) makes it quite sensitive to saturation and to “shoulders” (regions of reduced contrast) in camera tonal response. Slanted-edge MTF measurements are stable, reliable, and more representative of perceived image sharpness under a wide range of conditions (in addition to their many well-known […]

A comparison of sensitivity to signal processing In this page we address concerns about the sensitivity of slanted-edge patterns to signal processing, especially sharpening, and we correct the misconception that sinusoidal patterns, such as the Siemens star, are insensitive to sharpening, and hence provide more robust and stable MTF measurements. The Siemens Star is of particular interest because, along with the slanted-edge, it is included in the ISO 12233:2014 standard.  To summarize our results, we found that sinusoidal patterns are sensitive to sharpening, though often less so than low contrast (4:1) slanted-edges. The relatively high contrast of the Siemens Star […]

SFRplus and eSFR ISO can tolerate moderate amounts of optical distortion (pincushion or barrel), but they have definite limits. In this page we describe special versions of SFRplus and eSFR ISO charts that can work with highly barrel-distorted (“fisheye“) lenses, with fields of view up to around 160 degrees— which are used in a number of applications, particularly for automotive rear-view and sports cameras. Cameras with fields of view over 160 degrees— even approaching 360 degrees— can be tested with the SFRreg module, which uses multiple individual “registration mark” charts facing the camera. Pre-distorted charts should only be used with […]

Running eSFR ISO – Rescharts eSFR ISO – eSFR ISO setup window – Speeding up – More Settings window – Secondary Readouts – Gamma – Auto mode settings – Warnings – eSFR ISO summary Running eSFR ISO Imatest eSFR ISO performs highly automated measurements of several key image quality factors using one of three versions of the ISO 12233:2014 Edge SFR chart: Standard, Enhanced, or Extended. This document shows how to run eSFR ISO in Rescharts and how to save settings for automated runs. Part 1 introduced eSFR ISO and explained how to obtain and photograph the chart. Part 3 […]

Imatest eSFR ISO performs highly automated measurements of several key image quality factors using versions of the new ISO 12233:2014 E-SFR (Edge SFR) test chart that may be purchased from the Imatest store (recommended) or printed on a high-quality inkjet printer. Region of Interest (ROI) selection is automatic, based on user-entered criteria (similar to  SFRplus, which it closely resembles). Image quality factors include: Sharpness, expressed as Spatial Frequency Response (SFR), also known as Modulation Transfer Function (MTF) Lateral Chromatic Aberration Distortion (with less detail than the Distortion module). Details in SFRplus Distortion and Field of View measurements. Noise, measured from the […]

Imatest eSFR ISO results Imatest eSFR ISO performs highly automated measurements of several key image quality factors using one of three versions of the ISO 12233:2014 Edge SFR chart: Standard, Enhanced, or Extended. 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, measured from the grayscale patches surrounding the center of the chart, includes all types of noise calculated by Color/Tone Interactive and Color/Tone Auto (standard pixel noise, chroma noise, scene-referenced noise, sensor (raw) […]

Introduction This page briefly illustrates how to use the Imatest with Omnivision OVTAPantherM. Please note that Omnivision cameras are not supported in the OSX and Linux version of Imatest. However, Imatest supports other development systems to varying degrees. Contact us for details. Load images directly from Omnivision sensors. This eliminates the need to capture images separately, store them, then load them individually into Imatest, dramatically improving productivity. Download and Install Software To download Imatest software, go to store.imatest.com/software.html Download and open the self-extracting executable (Imatest-IS-3.n.exe). This will install the Imatest Master edition and the Matlab Compiler Runtime (MCR), which is required […]

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 […]

Introduction This page illustrates how to use image acquisition with ON Semiconductor DevWare, which is a part of ON Semiconductor’s DevSuite. Imatest also supports other development systems. Load images directly from DevWare. This eliminates the need to capture images separately, store them, then load them individually into Imatest, dramatically improving productivity. Note: As of Imatest 5.0 image acquisition capabilities were added to Imatest Master and Imatest IS was discontinued. Learn more.  Download and Install Software To download Imatest Master software, go to www.imatest.com/products/imatest-master/ Download and open the self-extracting executable (Imatest-IS-3.n.exe). This will install Imatest and the Matlab Compiler Runtime (MCR), which is required for […]

The Pass/Fail monitor (introduced In Imatest 4.0) provides a real-time indication of whether a device has passed or failed a test. It saves the trouble of digging through results— in figures or CSV or JSON files. Key features: It can stay open while modules run, displaying results immediately after calculations are complete. It works best on systems with a high resolution screen or dual screens. It interfaces with most Imatest analysis modules. It can be extremely valuable for developing and testing Pass/Fail criteria for Imatest IT (Industrial Testing). It can call several utilities for helping with this process. It displays […]

In January 2013 Imatest released the Spilled Coins test chart, which is an improved version of the Dead Leaves chart for measuring a camera’s fine texture response. (It’s available in the Imatest Store in both monochrome and color versions.) Shortly afterwards, Jason Cope of our partner company Image Quality Labs found an anomalous result and called me to find out what was wrong. When I looked at the image I realized that he’d done the test correctly. He had found an image whose processing defeated the intent of the dead leaves chart, which is to accurately measure a camera’s texture […]

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 […]

Introduction Imatest’s slanted-edge algorithms for calculating MTF/SFR are based on ISO 12233 standard, “Photography – Electronic still picture cameras – Resolution measurements”. Although this standard is well-established in industry, we often receive questions regarding its validity. This document describes methods for validating the Imatest slanted-edge method for calculating image sharpness (expressed as Modulation Transfer Function, MTF, which is synonymous in practice with Spatial Frequency Response, SFR). MTF is a measurement of image contrast as a function of spatial frequency. As such, it is a measure of device or system sharpness, which is only indirectly related to perceived image sharpness in […]

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 […]