As of Imatest 5.0, Imatest Master now features image acquisition capabilities. Previously, image acquisition capabilities were supported by Imatest IS, which has been discontinued as a separate product. This provides all of our customers with 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. Direct image acquisition cuts out several steps in the image quality testing process and allows for in-the-loop testing with Imatest.
Shooting the Great American Total Solar Eclipse
As predicted by astronomers years in advance, a peculiar cosmic event will occur on the morning of August 21st. Passing directly in front of the sun, the moon will cast a shadow racing across North America at supersonic speeds. From Salem, Oregon to Charleston, South Carolina, the 70 mile wide shadow will darken everything in its path. Outside the path of totality, all of North America will still be able to observe a partial solar eclipse! (more…)
Challenges in Automotive Image Quality Testing
Imatest’s Norman Koren presents his vision for challenges in automotive image quality testing including resolving low-contrast scenarios.
Closing the Loop: Distortion Correction
Imatest’s charts and software allow you to measure the characteristics and parameters of imaging systems. Quite often these measurements simply indicate the limits of system performance and expected image quality.
But some Imatest results let you improve image quality— and subsequent images taken by the same system— by correcting measured aberrations. (more…)
The Effects of misregistration on the dead leaves cross-correlation texture blur analysis
This paper was given as part of the Electronic Imaging 2017 Image Quality and System Performance XIV and Digital Photography and Mobile Imaging XIII sessions.
When: Tuesday, January 31, 2017, at 12:10 pm
By: Robert Sumner with support from Ranga Burada, Noah Kram (more…)
Measuring MTF with wedges: pitfalls and best practices
This paper was given as part of the Electronic Imaging 2017 Autonomous Vehicles and Machine session.
When: Monday, January 30, 2017, at 10:10 am
By: Norman Koren with support from Henry Koren, Robert Sumner (more…)
Testing a macro lens using Checkerboard and Micro Multi-slide
Imatest’s Checkerboard module is our new flagship module for automated analysis of sharpness, distortion and chromatic aberration from a checkerboard (AKA chessboard) pattern. The big benefit of using the checkerboard is that there are looser framing requirements than with other kinds of test targets. While checkerboard lacks the color and tone analysis provided by SFRplus and eSFR ISO, these features are not available on the high precision chrome on glass substrate, so the checkerboard is the optimal pattern for this test.
Using Sharpness to Measure Your Autofocus Consistency
Autofocus plays a major role in many camera system applications with variable focus, including consumer electronic devices. Camera systems must be able to focus at a variety of distances. Optical systems on cameras only allow a certain range of distances from the camera to be in focus at once (this is often known as the depth of field, or depth of focus). (more…)
Imatest Support for CPIQ Metrics
What is CPIQ?
IEEE-SA working group P1858 created the CPIQ standard. CPIQ seeks to standardize image quality test metrics and methodologies across the mobile device industry, correlate objective test results with human perception, and combine this data into a meaningful consumer rating system.
(more…)
Color difference ellipses
Starting with Imatest 4.2, Imatest’s two-dimensional color displays— CIELAB a*b*, CIE 1931 xy chromaticity, etc.— in Multicharts, Multitest, Colorcheck, SFRplus, and eSFR ISO can display ellipses that assist in visualizing perceptual color differences. You can select between MacAdam ellipses (of historical interest), or ellipses for ΔCab (familiar but not accurate), ΔC94, and ΔC00 (recommended).
Measuring Multiburst pattern MTF with Stepchart
Measuring MTF is not a typical application for Stepchart— certainly not its primary function— but it can be useful with multiburst patterns, which are a legacy from analog imaging that occasionally appear in the digital world. The multiburst pattern is not one of Imatest’s preferred methods for measuring MTF: see the MTF Measurement Matrix for a concise list. But sometimes customers need to analyze them. This feature is available starting with Imatest 4.1.3 (March 2015).
LSF correction factor for slanted-edge MTF measurements
A correction factor for the slanted-edge MTF (Edge SFR; E-SFR) calculations in SFR, SFRplus, eSFR ISO, SFRreg, and Checkerboard was added to Imatest 4.1.2 (March 2015). This correction factor is included in the ISO 12233:2014 standard, but is not in the older ISO 12233:2000 standard. Because it corrects for an MTF loss caused by the numerical calculation of the Line Spread Function (LSF) from the Edge Spread Function (ESF), we call it the LSF correction factor. (more…)
Slanted-Edge versus Siemens Star: A comparison of sensitivity to signal processing
This post addresses concerns about the sensitivity of slanted-edge patterns to signal processing, especially sharpening, and corrects the misconception that sinusoidal patterns, such as the Siemens star (included in the ISO 12233:2014 standard), are insensitive to sharpening, and hence provide more robust and stable MTF measurements. (more…)
Sharpness and Texture Analysis using Log F‑Contrast from Imaging-Resource
Imaging-resource.com publishes images of the Imatest Log F-Contrast* chart in its excellent camera reviews. These images contain valuable information about camera quality— how sharpness and texture response are affected by image processing— but they need to be processed by Imatest to reveal the important information they contain.
*F is an abbreviation for Frequency in Log F-Contrast.
No Perfect Lens, No Perfect Lens Test
Roger Cicala of LensRentals.com has completed the second part of his two part series investigating lens testing. (more…)
Transmissive Chart Quality Comparison
Imatest currently sells several transmissive (backlit) test charts, which have a range of substrates, each with specific properties and qualities that are in process of being quantified. The following comparison of the most important of our transmissive substrates was prepared in response to several customer inquiries.
Measuring Test Chart Patches with a Spectrophotometer
Using Babelcolor Patch Tool or SpectraShop 4
This post describes how to measure color and grayscale patches on a variety of test charts, including Imatest SFRplus and eSFR ISO charts, the X-Rite Colorchecker, ISO-15729, ISO-14524, ChromaDuMonde CDM-28R, and many more, using a spectrophotometer and one of two software packages.
- Babelcolor PatchTool which works with reflective test charts
- Robin Myers SpectraShop 4 which works with both reflective and transmissive (backlit) test charts
Slanted Edge Noise reduction (Modified Apodization Technique)
For measurement of sharpness, the main driver of variation is noise. A powerful noise reduction technique called modified apodization is available for slanted-edge measurements (SFR, SFRplus, eSFR ISO and SFRreg). This technique makes virtually no difference in low-noise images, but it can significantly improve measurement accuracy for noisy images, especially at high spatial frequencies (f > Nyquist/2). It is applied when the MTF noise reduction (modified apodization) checkbox is checked in the SFR input dialog box or the SFRplus or eSFR ISO More settings window. (more…)
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