We now offer a complete, customizable image quality testing solution for Security camera systems to provide our customers with an easy, effective way to outfit their labs. While working with some of the top security camera manufacturers, our engineers have compiled all of the necessary lab materials in a convenient package. The package includes options for software; reflective, transmissive, tunable, and ultra-wide light sources; test fixtures for a variety of fields-of-view and focus distances; and applicable test charts to analyze crucial image quality factors.
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. Here are the top three new features, and why should upgrade to Imatest 5.1:
- Compensate for chart MTF to perform accurate high-resolution or close-distance sharpness tests
MTF Compensation reduces the impact of the chart on measured imaging system MTF.
- Geometrically calibrate single or multi-camera devices obtaining camera intrinsic and extrinsic matrices for accurate machine vision and ADAS applications
A geometrically calibrated device provides a mapping between pixel coordinates and real-world position.
- Direct image acquisition for Sony sensors
Imatest now supports direct image acquisition from Sony sensor development boards through the Sony AYA software tool.
It is important to test your camera system in environments which reproduce lighting conditions similar to where you intend to use the camera in the real world. Failure to test a camera under low light conditions may lead to overstating the camera’s performance.
Image sensors collect light (signal) into pixel wells, then convert the resulting analog voltage levels into digital numbers. Dark current is where electrons are released from thermal activity which becomes indistinguishable from electrons released via photoresponse. The dark current that exists in uncooled image sensors leads to dark noise. At low light levels, exposures are longer to gather more light, which gives more time for dark-current electrons to be gathered. This leads to dark noise and read noise representing a larger portion of the overall response, which reduces the signal to noise ratio (SNR). Low-light conditions are most challenging for higher resolution sensors with small pixel pitches where the particle and wave nature of light can seriously impact the performance of your camera. (more…)
In this post, we will be using the Contrast Resolution Chart and Imatest Master to measure the dynamic range of a Google Pixel 2 XL. The dynamic range of a camera is the reproducible tonal range in an imaging system. Put simply, it is the range between the darkest black and the brightest white of an image and is typically measured in decibels (dB). It is an important image quality factor in many applications from machine vision to mobile cameras and more recently, automotive camera systems. In this use case, we will be evaluating both the HDR+ (default) and HDR off modes of the Pixel 2 XL; however the procedure can be used to test any camera system’s dynamic range. You can read more details about Imatest’s dynamic range test solutions
The obsolete ISO 12233:2000 standard defines a resolution test target with a high contrast ratio, These are typically produced at the maximum dynamic range of a printer which can be anywhere from 40:1 to 80:1. The high contrast can lead to clipping of the signal which leads to overstated invalid MTF values.
Some camera manufacturers who want better MTF results may take advantage of this anomaly to overstate the quality of the cameras they produce. This is why it is critical to validate cameras with a proper measurement system that includes a low-contrast target. (more…)
The dynamic range of recent HDR image sensors, defined as the range of exposure between saturation and 0 dB SNR, can be extremely high: 120 dB or more. But the dynamic range of real imaging systems is limited by veiling glare (flare light), arising from reflections inside the lens, and hence rarely approaches this level. Veiling glare measurements, such as ISO 18844, made with black cavities on white fields, result in large numbers that are difficult to relate to dynamic range. Camera dynamic range is typically measured from grayscale charts, where veiling glare depends on the design and layout of the chart, leading to inconsistent results. (more…)
The release of Imatest 5.0 introduced a number of powerful new features, including the Arbitrary Charts module which enables Imatest analysis of test chart designs which would be otherwise unsupported by the software. This new module allows user-defined chart layouts for any situation which requires one.
The primary concept of Arbitrary Charts is that the user supplies a chart-definition text file which declares the location and properties of features on a test chart. The features can be placed in essentially any configuration and Imatest will still be able to automatically analyze the chart.
Here at Imatest, we believe we’ve designed some very comprehensive test charts, such as our flagship SFRplus and eSFR-ISO charts. These charts are designed to provide a number of image quality factor measurements, work with an extremely wide range of cameras, are available in pre-distorted versions for wide-angle lenses, and more. They each have their own dedicated modules in Imatest which recognize these chart designs.
While we highly recommend the use of these and our other standard charts, we also recognize that there are situations which may require a more custom target. For example:
Working with a legacy database of test images of an older chart
Meeting a test spec which requires specific, non-standard targets
custom reticles for collimator systems
Special combination charts for accelerated testing
P1858 Combination Chart Conception
As mentioned above, some situations require a custom target, including the need to combine charts for accelerated testing. Early in 2017, a customer and frequent collaborator approached us about adding support for a new chart. The IEEE p1858-2016 Cell Phone Image Quality standard requires images of at least five different standard test charts for the complete set of seven metrics. The customer wanted to significantly reduce the need for several charts by developing a test chart that provides a “good enough” measurement of all of the metrics from a single image. We worked together with them, jointly developing what would become the P1858 Variation Combo Chart and the Arbitrary Charts Module.
The immediate goal in this case was to reduce testing time of a device by at least a factor of five. (This is likely a low bound on the time savings, as switching between test targets is typically the most time-intensive part of a well-tuned automatic test bench.) The customer wanted results that, even if they weren’t technically in spec, would provide an indication of how a test device would score on a full-fledged CPIQ test, and wanted them to be produced quickly.
This would, of course, require a set of compromises on the CPIQ metrics:
SFR measurements from just outside of the center of field, instead of dead center
24 color patches based on the X-Rite ColorChecker instead of the 140 of the ColorChecker SG
Color Uniformity results measured from the chart background areas between the other features, rather than an entire flat-field image
Chromatic Aberration and Geometric Distortion measurements from slanted edges around the field, instead of the dot pattern
These changes from the CPIQ spec were deemed acceptable for this purpose, and the P1858 Combination Chart was born. This design is now publically available, with the approval of the original customer.
Using the Arbitrary Charts Module
We have been very happy to collaborate with Imatest on their new 5.0 release to allow us to design a combination chart that reduces our objective metric capture needs, improving our productivity and eliminating the challenge of correlating data from multiple capture conditions.
– Lead Imaging Scientist, Imatest Customer
At first glance, the P1858 Combination Chart looks very similar to Imatest’s standard eSFR-ISO chart.
The most obvious difference here is that there is the dead leaves texture pattern in the center of the chart instead of a slanted square. However, there are many other subtle differences which would make this completely unusable by our standard eSFR-ISO module:
The grayscale OECF patches have been enlarged and moved outward
Extra color patches have been added to approximate all of the patches on the X-Rite ColorChecker
Four individual slanted edges have been added on the inside of the OECF patches, so SFR measurements are still possible near center of field
In general, the positioning of wedges and slanted squares is different
These differences preclude any standard module in Imatest from performing an automatic analysis of the chart (though selections of slanted edges and wedges could be made manually in individual images using the SFR and Wedge modules, respectively – not a great solution).
Fortunately, this chart was designed in concert with the development of the Arbitrary Charts module, with the express purpose of making analysis of this sort of chart automatic and systematic. Moreover, not only can the combined results be produced from a single image but they are produced from a single module run in Imatest. Instead of running a module to analyze the color, a module for sharpness, a module for uniformity, etc., the Arbitrary Charts module simplifies the testing procedure and output parsing.
The ability to configure our own charts is revolutionizing our approach to quantitative image quality testing and test development.
-Lead Imaging Scientist, Imatest Customer
As an added bonus, the customer is able to make slight changes to this design at will and simply update the chart definition file supplied to the module, without having to wait for new builds of Imatest to catch up.
Learning to Use Arbitrary Charts
The capability to analyze user-defined charts is new in Imatest 5.0, and is under continual development. New capabilities are being added to the Arbitrary Charts module with each release.
Further information about the Arbitrary Charts module and its current capabilities can be found on its documentation page.
The most important novel aspect of working with this module is the introduction of the chart definition file which enables the software to understand images of the test chart. To help communicate the role and construction of this file, we are producing a series of short videos that describes the process.
This week, we launched Imatest 5.0. We built Imatest 5.0 to provide users with a streamlined workflow for more efficient image quality analysis. Here are five reasons to start using Imatest 5.0 today.
Refined User Experience
Imatest 5.0 features several new tools and enhancements across our products to help you improve your workflow. Whether you want to reduce the number of images needed for complete system qualification with Arbitrary Charts; process a collection of images with automated analysis routines within the brand new Test Manager, or process batches of images with our enhanced image processing module, Imatest 5.0 is an improved experience for users needing an expedited testing process.
Innovative Image Quality Measurements
The newest release provides several new and enhanced measurements to help your focus on the image quality factors that matter to your business’ camera system.
- Contrast Resolution was designed for the visualization and measurement of contrast separation. This is particularly important for the automotive industry where camera systems need to distinguish between low contrast objects in a larger field with varying ranges of brightness.
- The ISO 18844 flare measurement added to the Uniformity module was created to address the need to accurately measure veiling glare.
- The enhancements to the SFRreg Center Chart provides geometric utilities for measuring tilt and rotational measurements, an especially important factor for users needing to test wide-angled measurements.
Focus on the image quality factors that matter most
Imatest tools serve many industries with widely varying requirements, for example testing an automotive camera system is different from testing a consumer device. Even within one industry, companies need to test several image quality factors on several test charts, complicating the capture analysis workflow. Imatest 5.0 lets you zero in on the image quality factors and results that matter most to your business.
- Customizable reports allows users to more efficiently filter and present select image quality data from a variety of image quality factors.
- The new arbitrary charts functionality serves a similar purpose by letting users define efficient layouts of analysis features within one chart.
Enhanced support for industry standards
Industry standards provide a foundation for the testing and analysis of imaging systems and clearly define testing methods for reliable measurements of system performance. Imatest 5.0 goes along way to support and supplement industry testing standards.
Run predefined test plans for standard testing procedures such as CPIQ within the new Test Manager.
The new P1858 Variant Combo chart, supported by Arbitrary Charts, combines several analysis features required by the standard into one chart. This enables users to minimize the number of images needed in the testing process and increases testing efficiency and accuracy.
Imatest 5.0 also features an enhanced Uniformity module to support the ISO 18844 standard for image flare measurements on digital cameras. The standard was created to address some of the difficulties of making ISO 9358 measurements with cameras.
Streamlined Product Line
The Imatest 5.0 release includes the streamlining of the Imatest product line. As of Imatest 5.0, Imatest Master will now includes image acquisition capabilities that were previously available in Imatest IS, which is now discontinued. Imatest users will now have access to the acquisition library. The library supports direct acquisition from a wide range of frame grabbers and cameras, as well as industry standard interfaces like CameraLink, GigE Vision, and USB through DirectShow (Windows) or QuickTime (OS X). Direct image acquisition cuts out several steps in the image quality testing process and allows for in-the-loop testing with Imatest.
In order to maximize performance in the new Test Manager, we utilized parallel processing. Previously, parallel processing was only available in Imatest IT-P. With the release of Imatest 5.0, Imatest IT-P functionality is now included in Imatest IT . This enables all Imatest users to rapidly process large volumes of images. By utilizing high-performance processors with 6+ cores, parallel processing can improve throughput by over 2.5x.