Nyquist frequency, Aliasing, and Color Moire

Although sharpness is an important image quality factor, a sharper lens is not always better. A lens can be too sharp for a sensor, resulting in disturbing visual artifacts. These artifacts, which include “stair-stepping” and moiré patterns (low frequency patterns that can be strongly colored), can appear because of a property that digital cameras share with all digitally sampled systems— a maximum spatial frequency, called the Nyquist frequency, beyond which scene information cannot be correctly reproduced. Any information above the Nyquist frequency that reaches the sensor will be aliased to a lower spatial frequency, which can result in the artifacts described below. […]

October 4, 2018March 24, 2023 Christan Taylor

Considerations when evaluating a Near Infrared camera

Recent growth in the automotive and security industries has increased the number of cameras designed for viewing both Near Infrared (NIR) and visible wavelengths of light. NIR illumination is invisible to the human eye and can light a dark scene without being visible or annoying.

September 24, 2018April 7, 2020 Henry Koren

Increasing the Repeatability of Your Sharpness Tests

By Robert Sumner With contributions from Ranga Burada, Henry Koren, Brienna Rogers and Norman Koren Consistency is a fundamental aspect of successful image quality testing. Each component in your system may contribute to variation in test results. For tasks such as pass/fail testing, the primary goal is to identify the variation due to the component and ignore the variation due to noise. Being able to accurately replicate test results with variability limited to 1-5% will give you a more accurate description of how your product will perform.

ISO 12233 Edge SFR (eSFR) Inkjet chart

Imatest ISO 12233:2017 and ISO 12233:2023 eSFR charts are implementations of the Low Contrast Edge SFR (eSFR) test chart illustrated in Section 6.1 and Annex C of the ISO Standard Document. The chart is available in two general versions:

Enhanced: extra squares, wedges, and color patterns when printed with technologies that allow color
Extended: similar to Enhanced, but with a 16:9 aspect ratio, suitable for HDTV and cinema (Note: Works with Matlab esfrChart)
All inkjet charts are available in either Visible or Near Infrared and Visible for testing cameras sensitive to wavelengths between 700-1000 nm. Specific spectral data available upon request. We currently offer these charts in inkjet format, with Enhanced versions available as photographic prints. All Imatest ISO 12233 eSFR charts are fully compliant with the ISO standard. The Imatest eSFR ISO module provides highly automated support for the new charts. Additional details below. Download PDF Info Sheet

July 27, 2018April 7, 2020 Imatest Admin

Introducing Imatest 5.1

Our engineers are continually adding new features and updating Imatest software to provide you with the best analysis tool on the market. In our most recent release, our team has added several new modules to provide you better analysis tools.

Imatest 5.1

Version 5.1 has added several new features on top of the major enhancements made in version 5.0. Among the new features are MTF Compensation, Geometric Calibration, and Sony Sensor Image Acquisition. Not sure if you want it yet? Download a free trial. MTF COMPENSATION GEOMETRIC CALIBRATION DISTORTION CALCULATION TEMPORAL NOISE MEASUREMENTS SONY AYA IMAGE ACQUISITION SYNTHETIC RAW FILE CREATION

Rescharts slanted-edge modules Part 4: Other results

Imatest Rescharts slanted-edge modules perform highly automated measurements of several key image quality factors using specially-designed test charts. The user never has to manually select Regions of Interest (ROIs). This page covers results that are (mostly) not derived from the slanted-edges themselves, including Noise (best in eSFR ISO) Distortion (differing detail in different modules; best with SFRplus and eSFR ISO. Described in detail here. Tonal response* (no noise statistics for SFRplus) Color accuracy* when used with an SFRplus, eSFR ISO, or SFRreg center charts that contain a color pattern Vanishing resolution, aliasing, and Moiré from Wedge patterns in eSFR ISO ISO sensitivity* (Saturation-based and […]

Rescharts Slanted-Edge Modules Part 3: Edge Results

Imatest Rescharts slanted-edge modules perform highly automated measurements of several key image quality factors using specially-designed test charts. The user never has to manually select Regions of Interest (ROIs). This page covers results that are derived from the slanted-edges, and hence are found in all Rescharts slanted-edge modules. It also covers text output (CSV and JSON) files. Sharpness, expressed as Spatial Frequency Response (SFR), also known as the Modulation Transfer Function (MTF), Lateral Chromatic Aberration Other results, not derived from slanted-edges are covered in Part 4. Noise (best in eSFR ISO), Distortion (differing detail in different modules; best with SFRplus and eSFR […]

Using Rescharts slanted-edge modules Part 2

Running Rescharts slanted-edge modules (Interactive and Auto mode settings) Imatest Rescharts slanted edge modules— SFRplus, eSFR ISO, SFRreg, and Checkerboard— perform highly automated measurements of several key image quality factors using specially-designed test charts. This document shows how to run these modules in Rescharts and how to save settings for automated runs. Four introductory pages — SFRplus, eSFR ISO, SFRreg, and Checkerboard — describe each module and explain how to obtain and photograph the chart. Rescharts Results Part 3 and Part 4 illustrate the results. Selecting files – Setup window – ROI selection & analysis – Edge ID files – More settings window […]

Getting Started With Image Quality Testing

Overview Why Imatest? | Test Charts | Lighting | Image Capture Technique | Setting up Your Lab | Using Imatest Software Why Imatest? Introduction Imatest charts and software allow you to measure the characteristics and quality of cameras and imaging systems. To begin measuring the resolution or color of your camera, you’ll need an image of a test chart. Imatest offers all-in-one test charts that can test a wide variety of image quality factors with one image. We also offer specialized test charts for measuring system properties like dynamic range, […]

March 1, 2018October 18, 2019 Henry Koren

Megapixel suitability for test charts

Megapixel suitability is based on the analysis of the Modulation Transfer Function (MTF) that is obtained from slanted-edge chart images captured at magnifications of around 0.5× (for inkjet charts) or 1× (for photographic charts) using a high quality DSLR or mirrorless camera and macro lens. The calculations are described in the following links: Compensating camera MTF measurements for chart and sensor MTF (Imatest 5.1+); i.e., Introduction, Calculation, MTF compensation files, Applying the compensation, and Lens MTF measurements sections. Chart Quality Calculator (Imatest 5.1+)—determine the suitability of a chart (based on MTF measurements for specific media and print methods) for a specific application. Test […]

Nonuniformity Correction in grayscale and color chart modules

Imatest can correct for nonuniform illumination and lens response (vignetting) in Imatest modules that analyze grayscale and/or color charts, including Color/Tone Setup (formerly Color/Tone Interactive), Color/Tone Auto (formerly Color/Tone Auto), Colorcheck, and Stepchart. Nonuniformity correction involves reading and specifying a second image, taken from a flat-field target (plain gray or white) under identical conditions to the test image. Note that the correction described in this page is not the same as nonuniformity correction for slanted-edge MTF measurements. Not also that Color/Tone Interactive (a highly interactive module) and Color/Tone Auto (a batch-capable fixed version of Color/Tone Interactive) are recommended for new […]

January 26, 2018October 4, 2022 Henry Koren

Lightbox Uniformity Comparison

Summary table – Detailed uniformity measurements – How we made the measurements Lightbox summary table. Many are no longer available from Imatest Lightbox Brightness Uniformity* CRI (spec.) Viewing Area Dimensions Controls Imatest LED Lightbox 1 to 100,000 lux ** 90 to 95% Over 97 260 x 220 mm to 1440 x 1100 mm (9 Sizes) 400 (W) x 380 (H) x 200mm (D) to 1655 x 1296 x 200 mm (9 Sizes) WiFi, USB, Manual Imatest LED Light Panel 30 to 1,000 lux 90 to 95% 229 x 152mm to 907 x 680mm (5 Sizes) 289 x 212 x 40mm […]

Chart Quality Calculator

Imatest 5.2 has several new features that let you use measured chart modulation transfer function (MTF) to do the following: Determine the suitability of a test chart characterized by size (height), print media, and printing technology for camera MTF measurements where the camera is characterized by pixel size, which is typically the number of vertical pixels. This can help determine the appropriate test chart for a specific application. This capability has been enhanced in Imatest 5.2 with the addition of the Chart suitability display. Increase the accuracy of MTF measurements by dividing the measured camera MTF by the appropriately scaled chart […]

Change Log

To obtain the latest version of Imatest (for updates, new installations, and trial as well as and full versions) go to Imatest Download. Imatest perpetual license holders are entitled to free updates for one year from the date of purchase. After that you need to renew. If your license is not current, you can download and install the version that was current one year after the purchase date. Join Imatest’s Pilot Program and gain early access to new Imatest features and bug fixes. Your feedback is incorporated into each official release to ensure you receive a seamless transition to new versions. […]

Legacy Change Log

The main change log is availabe for newer releases. Date Release Description Oct. 1, 2013 3.10 The new Multitest module (known briefly as ColorTest in 3.10) can analyze all the color and grayscale test charts supported by Multicharts in a fixed (i.e., non-interactive) module that can analyze chart image files in batches. It also includes most Stepchart and Colorcheck function. Five new fixed modules that can also operate in batch mode have been created from Rescharts modules: Random/Dead Leaves, Star chart, Log F-Contrast, Wedge, and Any Image Sharpness. These modules can be accessed by clicking the Modules dropdown menu in […]

Arbitrary Charts Analyses and Output

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 […]

Infrared

Imaging systems designed to capture infrared light vary greatly depending on application. Some examples include the automotive and security industries as well as remote sensing and facial recognition. Imatest offers an array of targets that can be analyzed with Imatest Master and Imatest IT to provide statistics and metrics for accurate system benchmarking. Targets Near Infrared (720nm – 1100nm) Near Infrared (NIR) charts can be produced on reflective and transmissive substrates. Inkjet targets work well in the NIR with some tonal adjustments made to compensate for contrast change in the longer wavelengths. Many of Imatest’s […]

Set of ISO-16505 Test Charts (6 charts)

The ISO-16505 bundle is made up six charts that are mentioned in various parts of the ISO-16505, Road vehicles — Ergonomic and performance aspects of Camera Monitor Systems standard.

This set of charts is available in three standard sizes: 2x, 4x and 5.5x. Select the ISO size you need based on the table below. Click on the ISO size for pricing and to order.

The 2x size replicates the charts as closely as possible to what is described in the standard. The 5.5x is the maximum size Inkjet possible. Custom sizing is available upon request.

Find more information, visit our ISO 16505 Road Vehicle Camera Monitor Systems Solution page and our Automotive Solutions page.

Arbitrary Charts Module Settings

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 […]