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).
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 in 2015. This correction factor is included in the ISO 12233:2014 and 2017 standards, 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…)
by Jackson K.M. Roland
Abstract
The slanted-edge method of measuring the spatial frequency response (SFR) as an approximation of the modulation transfer function (MTF) has become a well known and widely (more…)
Managing Supply Chain Image Quality
Imatest just released the white paper Managing Supply Chain Quality with Imatest to outline best practices for putting in place a rigorous manufacturing quality control regime. (more…)
Imatest is proud to announce the official release of its new 4.0 image quality testing software. The Imatest 4.0 upgrade includes a number of refinements including enhanced automation capabilities and a more robust image quality testing experience. (more…)
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.
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April 2024. We have a new document that compares slanted-edges with Siemens stars. (I’m embarrassed to say I’d forgotten the existence of this post.) Slanted edge vs. Siemens star MTF calculations: 2024 white paper We compared images (simulated, JPEG, and raw; demosaiced and one undemosaiced) that contained a Siemens star and slanted edges. We found some interesting effects of demosaicing and concluded that both chart types may be required to fully characterize cameras that have low quality demosaicing and/or strong bilateral filtering (which sharpens edges but lowpass-filters smooth areas.) For most purposes, we prefer the slanted edge. |
We are happy to announce that Imatest Master 3.10-Beta is now available for Mac OS X
We are confident in the stability of the image quality testing algorithms in this version, but have kept the Beta tag on this release since there may be some minor issues that remain to be resolved before we remove the Beta tag. (more…)
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.