System Modulation Transfer Function Research Articles

Enhancing Applicability of Reversible UV Thermochromic Offset Inks: Edge Quality Parameters and Thermochromic Printing System Modulation Transfer Function.

Modern logo design is characterized by its ability to convey information through the use of various images and text compositions. These designs often use simple elements such as lines to capture the essence of a product. When using thermochromic inks in logo design, it is important to consider their composition and behavior, as they differ significantly from conventional printing inks. This study aimed to determine the resolution capabilities of the dry offset printing technique when using thermochromic ink, with the ultimate goal of optimizing the thermochromic ink printing process. Horizontal and vertical lines were printed using both thermochromic and conventional inks to compare the edge reproduction characteristics of the two ink types. Moreover, the impact of the type of applied ink on the share of mechanical dot gain of the print was investigated. Additionally, modulation transfer function (MTF) reproduction curves were generated for each print. Moreover, scanning electron microscopy (SEM) was conducted to investigate the surface of the substrate and prints. It was found that the quality of the printed edge produced by thermochromic inks can rival that of conventional inks. Thermochromic edges showed lower raggedness and blurriness values for horizontal lines, whereas line orientation proved to be insignificant in the case of vertical lines. MTF reproduction curves confirmed higher spatial resolution for vertical lines in the case of conventional inks, whereas they were identical for horizontal lines. The share of mechanical dot gain is not highly influenced by the ink type. SEM micrographs confirmed that the conventional ink smooths out the micro-roughness of the substrate. However, on the surface, the microcapsules of thermochromic ink (measuring 0.5-2 µm) are observable.

Using symmetric illumination and color camera to achieve high throughput Fourier ptychographic microscopy.

This study aims to develop a high throughput Fourier ptychographic microscopy (FPM) technique based on symmetric illumination and a color detector, which is able to accelerate image acquisition by up to 12 times. As an emerging technology, the efficiency of FPM is limited by its data acquisition process, especially for color microscope image reconstruction. To overcome this, we built an FPM prototype equipped with a color camera and a 4×/0.13 NA objective lens. During the image acquisition, two symmetric LEDs illuminate the sample simultaneously using white light, which doubles the light intensity and reduces the total captured raw patterns by half. A standard USAF 1951 resolution target was used to measure the system's modulation transfer function (MTF) curve, and the H&E-stained ovarian cancer samples were then imaged to assess the feature qualities depicted on the reconstructed images. The results showed that the measured MTF curves of red, green, and blue channels are generally comparable to the corresponding curves generated by conventional FPM, while symmetric illumination FPM preserves more tissue details, which is superior to the results captured by conventional 20×/0.4 NA objective lens. This investigation initially verified the feasibility of symmetric illumination based color FPM.

X-ray scintillator lens-coupled with CMOS camera for pre-clinical cardiac vascular imaging-A feasibility study.

We present the design and characterization of an X-ray imaging system consisting of an off-the-shelf CMOS sensor optically coupled to a CsI scintillator. The camera can perform both high-resolution and functional cardiac imaging. High-resolution 3D imaging requires microfocus X-ray tubes and expensive detectors, while pre-clinical functional cardiac imaging requires high flux pulsed (clinical) X-ray tubes and high-end cameras. Our work describes an X-ray camera, namely an “optically coupled X-ray(OCX) detector,” used for both the aforementioned applications with no change in the specifications. We constructed the imaging detector with two different CMOS optical imaging cameras called CMOS sensors, 1.A monochrome CMOS sensor coupled with an f1.4 lens and 2.an RGB CMOS sensor coupled with an f0.95 prime lens. The imaging system consisted of our X-ray camera, micro-focus X-ray source (50kVp and 1mA), and a rotary stage controlled from a personal computer (PC) and LabVIEW interface. The detective quantum efficiency (DQE) of the imaging system(monochrome) estimated using a cascaded linear model was 17% at 10 lp/mm. The system modulation transfer function (MTF) and the noise power spectrum (NPS) were inputs to the DQE estimation. Because of the RGB camera’s low quantum efficiency (QE), the OCX detector DQE was 19% at 5 lp/mm. The contrast to noise ratio (CNR) at different frame rates was studied using the capillary tubes filled with various dilutions of iodinated contrast agents. In-vivo cardiac angiography demonstrated that blood vessels of the order of 100 microns or above were visible at 40 frames per second despite the low X-ray flux. For high-resolution 3D imaging, the system was characterized by imaging a cylindrical micro-CT contrast phantom and comparing it against images from a commercial scanner.

Using Fourier ptychography microscopy to achieve high-resolution chromosome imaging: an initial evaluation.

.SignificanceSearching analyzable metaphase chromosomes is a critical step for the diagnosis and treatment of leukemia patients, and the searching efficiency is limited by the difficulty that the conventional microscopic systems have in simultaneously achieving high resolution and a large field of view (FOV). However, this challenge can be addressed by Fourier ptychography microscopy (FPM) technology.AimThe purpose of this study is to investigate the feasibility of utilizing FPM to reconstruct high-resolution chromosome images.ApproachAn experimental FPM prototype, which was equipped with or objective lenses to achieve a theoretical equivalent NA of 0.48 and 0.63, respectively, was developed. Under these configurations, we first generated the system modulation transfer function (MTF) curves to assess the resolving power. Next, a group of analyzable metaphase chromosomes were imaged by the FPM system, which were acquired from the peripheral blood samples of the leukemia patients. The chromosome feature qualities were evaluated and compared with the results accomplished by the corresponding conventional microscopes.Results The MTF curve results indicate that the resolving power of the FPM system is equivalent and comparable to the conventional microscope, whereas the performance of the FPM system is close to the conventional microscope. When imaging the chromosomes, the feature qualities of the FPM system are comparable to the results under the conventional lens, whereas the feature qualities of the FPM system are better than the conventional lens and comparable to the conventional lens.ConclusionsThis study initially verified that it is feasible to utilize FPM to develop a high-resolution and wide-field chromosome sample scanner.

THz linear array scanner in application to the real-time imaging and convolutional neural network recognition

Room temperature linear arrays (up to 160 detectors in array) from silicon metal- oxide-semiconductor field-effect transistors (Si-MOSFETs) have been designed for sub- THz (radiation frequency 140 GHz) close to real-time direct detection operation scanner to be used for detection and recognition of hidden objects. For this scanner, the optical system with aspherical lenses has been designed and manufactured. To estimate the quality of optical system and its resolution, the system modulation transfer function was applied. The scanner can perform real-time imaging with the spatial resolution better than 5 mm at the radiation frequency 140 GHz and contrast 0.5 for the moving object speed up to 200 mm/s and the depth of field 20 mm. The average dynamic range of real time imaging system with 160-detector linear array is close to 35 dB, when the sources with the output radiation power of 23 mW (IMPATT diodes) are used (scan speed 200 mm/s). For the system with 32-detector array, the dynamic range was about 48 dB and for the single-detector system with raster scanning 80 dB with lock-in amplifier. However, in the latter case for obtaining the image with the sizes 20×40 mm and step of 1 mm, the average scanning time close to 15 min is needed. Convolutional neural network was exploited for automatic detection and recognition of hidden items.

Lenseless X-ray nano-tomography down to 150 nm resolution: on the quantification of modulation transfer and focal spot of the lab-based ntCT system

The ntCT nano tomography system is a geometrically magnifying X-ray microscopy system integrating the recent Excillum NanoTube nano-focus X-ray source and a CdTe photon counting detector from Dectris. The system's modulation transfer function (MTF) and corresponding point spread function (PSF) are characterized by analyzing the contrast visibility of periodic structures of a star pattern featuring line width from 150 nm to 1.5 μm. The results, which can be attributed to the characteristics of the source spot, are crosschecked by scanning the source's electron focus over an edge of the structured transmission target in order to obtain an independent measurement of its point spread function. For frequencies above 1000 linepairs/mm, the MTF is found to correspond to a Gaussian PSF of 250 nm full width at half maximum (FWHM) . The lower frequency range down to 340 linepairs/mm shows an additional Gaussian contribution of 1 μm FWHM . The resulting resolution ranges at 3200 linepairs/mm, which is consistent with the visual detectability of the smallest 150 nm structures within the imaged star pattern.

Influence of Attitude Parameters on Image Quality of Very High-Resolution Satellite Telescopes

The image quality of very high-resolution satellite telescopes (VHRSTs) is affected by several factors, including optics, detector, pointing accuracy errors, attitude stability errors, and altitude variations. The charge-coupled devices with a time delay and integration (TDI) feature play a significant role along with the satellite attitude parameters in characterizing the VHRST image quality. The imperfection of the satellite control system to maintain the required pointing accuracy and attitude stability can lead to severe degradation in the quality of the acquired imagery. Hence, it is required to investigate their impacts carefully during the satellite preliminary design phase. In this article, the combined effect of the TDI steps, satellite attitude parameters, and orbital altitude variations on the image quality are investigated in detail. The results show that the image quality in the along- and cross-track directions are affected seriously in certain situations by the roll and pitch angular velocity bias. Furthermore, the proposed mathematical model in this article reveals that total modulation transfer function (MTF), as an image quality metric, is affected severely by the satellite altitude variation, particularly when employing a high number of TDI steps. For example, for a given scenario, when employing TDI steps of 64, the mathematical results show that the effect of a satellite altitude variation of 10 km will result in a 65% reduction in total system MTF.

Effects of aerosol modulation transfer function on target identification

Atmospheric aerosol effects are often overlooked in target acquisition studies. Typically, performance models only consider extinction and turbulence within the prediction processes. The aerosol modulation transfer function (MTF) is included in range acquisition algorithms to determine how scattering and absorption effects change the target identification predictions. We modeled the aerosols as monodisperse water droplets comparable to a tenuous fog or mist. Integrating the aerosol MTF into the system MTF gives the opportunity to utilize the night vision integrated performance model to predict the target identification range with aerosol contributions. The aerosol MTF is a function of range, water droplet composition, wavelength, and aperture size. The analysis focuses on these variables with an emphasis on wavelength dependence to characterize mid-wave and long-wave performance. Results show that the mid-wave systems have a substantial diffraction advantage over long-wave systems. Only in the limit of increasing optical depths do the mid-wave and long-wave performance models begin to converge, verifying that the aerosols can be the limiting factor for target identification.

Design of Very High Resolution Satellite Telescopes Part II: Comprehensive Performance Assessment

In Part I [1] , a Korsch-based optical telescope design of a very high resolution earth observation satellite with a ground sampling distance of 25 cm is presented. In this part II, a system performance evaluation of the Korsch optical design employing a time-delay and integration charge-coupled device is investigated. Several key performance metrics are assessed, including the system modulation transfer function (MTF), absolute signal-to-noise ratio (SNR), differential SNR, noise equivalent change of reflectance, and cutoff resolution. The level of the national imagery interpretability rating scales (NIIRS) for measuring the image quality is also predicted. The system MTF has been computed, involving optics, detector, platform, orbit, atmosphere, and target illumination conditions. The SNR has been analyzed at different target albedos, solar, and satellite zenith angles. A new strategy for expressing the system evaluation based on the low- and high-illumination conditions is adopted; providing the operational ranges of such metrics. The assessment shows that for the high- and low-illumination conditions, the predictable performance of the proposed telescope gives promising results and provides an acceptable image quality.

WITHDRAWN: Practical methods for characterizing the optical performance of digital camera-based imaging systems: image processing application using ImageJ

Abstract In this paper, practical and simple methods for characterizing the optical performance of a digital CCD camera equipped with a zoom lens using test targets projected by a Newtonian collimator coupled to an integrating sphere and a halogen light source are presented. The presented methods include the evaluation of the CCD camera system modulation transfer function (MTF), uniformity, dynamic range, linearity and signal-to-noise ratio (S/N) properties in the visible region of the spectrum. Through out this work image processing for the recorded target images is performed using ImageJ. In addition, the paper presents a comparison between MTF measurements collected with a 1951-USAF resolution test target and a slanted edge test target. Finally, simple mathematical expressions for the measured optical system performance properties are provided. The presented optical system characterization methods can provide researchers with the needed data when a CCD or CMOS digital camera is integrated with a lens system.

Practical Methods for Characterizing the Optical Performance of Digital Camera-Based Imaging Systems

In this paper, practical and simple methods for characterizing the optical performance of a digital CCD camera equipped with a zoom lens using test targets projected by a Newtonian collimator coupled to an integrating sphere and a halogen light source are presented. The presented methods include the evaluation of the CCD camera system modulation transfer function (MTF), uniformity, dynamic range, linearity, and signal-to-noise ratio (S/N) properties in the visible region of the spectrum. Through out this work image processing for the recorded target images is performed using ImageJ. In addition, the paper presents a comparison between MTF measurements collected with a 1951-USAF resolution test target and a slanted edge test target. Finally, simple mathematical expressions for the measured optical system performance properties are provided. The presented optical system characterization methods can provide researchers with the needed data when a CCD or CMOS digital camera is integrated with a lens system.

High-speed slot-scanning radiography using small-angle tomosynthesis: Investigation of spatial resolution.

This paper studies spatial resolution that is achievable with a fast slot-scanning tomosynthesis approach for orthopedic examinations. Hereby, we use parallel scanning motion implemented in a twin robotic x-ray system. We have measured and analyzed the modulation transfer function (MTF) for various combinations of scanning speed, x-ray tube voltage, pulse length, the nominal focal spot size as well as source-to-object distances. Moreover, we present a theoretical model which describes the system in terms of the MTF. The system was equipped with newly developed linear trajectory prototypes for slot scanning. The acquired images form the basis for a small-angle tomosynthesis reconstruction. In total, three different scanning speeds (27, 14, 8cm/s), pulse lengths (1, 2, 4ms), tube voltages (80, 100, 120kV), two nominal focal spot sizes (0.6, 1.0), and three source-to-object distances (950, 1050, 1150mm) were investigated. To determine the resolution capabilities, we measured the MTF for the given parameter space. The results were then used to design a filter that yields a desired resolution in the reconstructed image. In addition, we also measured the noise power spectrum (NPS) to show the influence of the aforementioned filters on the noise distribution. We have shown that the presented model is in good agreement with the performed measurements. Scanning speed and pulse width have an impact on the MTF in the scanning direction. Up to a travel distance of 0.3mm during an x-ray pulse, an isotropic resolution can be achieved. Longer pulse width or higher scanning speed cause anisotropic resolution. Moreover, it is shown that none of the investigated parameters have an influence on the MTF perpendicular to the scanning direction (slot direction). The 10% MTF value ranges between 9 and 18lp/cm in the scanning direction and about 18lp/cm in slot direction. Tube voltage, nominal focal spot size as well as the source-to-object distance showed no major impact on the system MTF. In terms of the anisotropic resolution capabilities, we have shown that limiting the resolution in the slot direction to obtain isotropic resolution is possible yet at the cost of an inhomogeneous noise pattern. However, maintaining the resolution in slot direction will provide a better edge response and a more homogeneous noise texture at the cost of an inhomogeneous image resolution. We have demonstrated the feasibility of the slot-scanning technique using a twin-robotic x-ray system. Even the fastest scanning mode (27cm/s) yields image resolution on a level that is sufficient for typical orthopedic examinations in terms of musculoskeletal (MSK) measurements. Moreover, it could be shown that the application of specifically designed target MTFs on two-dimensional x-ray images is feasible.

Resolution characterization of a silicon-based, photon-counting computed tomography prototype capable of patient scanning.

Photon-counting detectors are expected to bring a range of improvements to patient imaging with x-ray computed tomography (CT). One is higher spatial resolution. We demonstrate the resolution obtained using a commercial CT scanner where the original energy-integrating detector has been replaced by a single-slice, silicon-based, photon-counting detector. This prototype constitutes the first full-field-of-view silicon-based CT scanner capable of patient scanning. First, the pixel response function and focal spot profile are measured and, combining the two, the system modulation transfer function is calculated. Second, the prototype is used to scan a resolution phantom and a skull phantom. The resolution images are compared to images from a state-of-the-art CT scanner. The comparison shows that for the prototype are detectable with the same clarity as on the reference scanner at equal dose and reconstruction grid, with more line pairs visible with increasing dose and decreasing image pixel size. The high spatial resolution remains evident in the anatomy of the skull phantom and is comparable to that of other photon-counting CT prototypes present in the literature. We conclude that the deep silicon-based detector used in our study could provide improved spatial resolution in patient imaging without increasing the x-ray dose.

Basic Spatial Resolution Metrics for Satellite Imagers

Six basic criteria used to estimate the Ground Resolution Distance of satellite imagers are considered: Ground Sample Distance (GSD), Rayleigh diffraction limit, ground spot size, generalized Rayleigh resolution criterion, Sparrow limit, and the full-width at half-maximum (FWHM) of the Point/Line Spread Function (PSF/LSF). Theoretical arguments and experimental results that support the use of the LSF FWHM as a spatial resolution metric are presented. The procedure to compute the LSF FWHM from the system modulation transfer function is reviewed and is used to compute the FWHM of the three ideal sensors as a function of their optical factor, contrasting these theoretical results with 22 in orbit measurements. Within this context, the limited range of validity of the GSD and the Rayleigh diffraction limit as spatial resolution estimators is assessed. The limitations of the LSF FWHM as a resolution estimator are also noted.

Simultaneous aberration and aperture control using a single spatial light modulator.

A method to simultaneously control aberrations and the aperture of an optical system using a single phase-only spatial light modulator was investigated. The experiment was performed using a liquid-crystal-on-silicon spatial light modulator (LCoS-SLM) within an adaptive optics system used for visual testing, although the method has broader applications in adaptive optics field. The performance of the technique was characterized through the estimation of the system's modulation transfer functions (MTFs) by using a random chart method. MTFs obtained from the phase modulation-based approach were compared with those from using a real aperture (diaphragm). The areas under the MTFs for the two conditions were similar up to 98%, confirming that the low-pass filter effect associated to the size of the entrance pupil was similar for the phase-modulated pupil and the physical pupil. As an example of application, both aberrations and pupil were controlled by a single phase-only modulator to study the through-focus visual performance in real subjects. Limitations and possible enhancements of the presented method were also discussed. The presented technique reduces complexity and cost of adaptive optics systems. It opens the door to new experiments by allowing dynamic modulation of aberrations and apertures of any shape.

Influence of the System MTF on the On-Board Lossless Compression of Hyperspectral Raw Data

A noticeable topic to be pursued in the field of on-board real-time data processing is the influence of the modulation transfer function (MTF) of the image acquisition system on the lossless compressibility of raw (that is, uncalibrated) hyperspectral data. Actually, notwithstanding the system device is constrained by several design and manufacturing requirements, the impact of the on-board MTF on the performance of data compressors is becoming remarkable. In particular, the aim of reducing both transmission bandwidth/power and mass storage can be efficiently pursued. Such an analysis is expected to be useful especially for systems employed in mini-satellites, whose payload must be compact and light. From this perspective, this paper investigates the performance of a typical imaging system that acquires low/medium-spatial-resolution images, by considering high-resolution reference data, which simulate the real scene to be imaged. To this end, standard Consultative Committee for Space Data Systems (CCSDS) Aviris 2006 data have been chosen, due to their spatial resolution of 17 m, which is adequate to be a reference for simulated data whose spatial resolution is foreseen between 50 and 150 m. MTF requirements are usually provided based on the cut-off value of the amplitude at the Nyquist frequency, which is defined as a half of the sampling frequency. Typically, a cut-off value between 0 . 2 and 0 . 3 ensures that a sufficient amount of information is delivered from the scene to the acquired image, by avoiding at the same time the degradation due to an excessive aliasing distortion. All the scores are achieved by running the standard lossless compression scheme CCSDS 1.2.3.0-B-1 for multispectral/hyperspectral data, as a function of the cut-off value and different noise acquisition levels. The final results, and related plots, show that this analysis can suggest a suitable choice for the cut-off value, to ensure both a sufficient quality and low bit rates for the transmitted data to the ground station.

An experimental method to directly measure DQE at k = 0 for 2D x-ray imaging systems

The zero-frequency detective quantum efficiency (DQE), viz., DQE0, is defined as the ratio between output and input squared signal-to-noise ratio of an imaging system. In 1963, R. Shaw applied Fourier analysis to generalize DQE0 to the frequency-dependent DQE, i.e. DQE. Under conditions specified by Shaw, DQE is the same as DQE0 at k = 0. The experimental measurement of DQE involves the measurement of system modulation transfer function (MTF) and noise power spectrum (NPS). Although the measurement of MTF is straightforward, the experimental measurements of NPS encountered several challenges. As a result, some experimental methods may yield a nonphysical NPS value at k = 0, which makes the measured DQE(k)|k=0 deviate from the true zero-frequency DQE. This work presents new results from three aspects: 1) system drift is a significant error source when a large number of independent image acquisitions are involved in measuring NPS and DQE; 2) a cascaded systems analysis shows that the drift induces a global positive offset to the measured autocovariance function, and the offset is quantitatively related to the NPS error at k = 0; 3) based on the measured autocovariance data, drift-induced offset can be estimated, so that errors in the measured NPS(k)|k=0 and DQE(k)|k=0 can be corrected. Both numerical simulations with known ground truth for DQE0 and experimental studies were performed to validate the proposed measurement method. The results demonstrated that the method mitigates the undesirable influence of system drift in DQE(k)|k=0 and DQE0, allowing the measured values consistent with the classical definition of zero-frequency DQE.

Best Practices for Imaging System MTF Measurement

The modulation transfer function (MTF) describes how an imaging system modifies the spatial frequency content of a scene. Many performance metrics and specification requirements are strongly dependent on the MTF as it provides information on the limiting resolution of the imaging system. In this correspondence we will identify potential issues that can contribute uncertainty or bias into the MTF measurement, and suggest best practices to avoid such issues. Beginning with a full 2D derivation of the tilted edge measurement technique, we identify potential areas where differences between laboratories can occur due to the setup, imaging system, measurement procedure, or the measurement processing. We show specific examples of how the system’s nonuniformity (including defective pixels) can affect the observed MTF. Additionally, we show examples of target to target variation and the effects of dynamic range. A summary table is provided on best practices to reduce the impact of the identified potential areas of difference. In support of the reproducible research effort, the Matlab functions associated with this work can be found on the Mathworks file exchange [1].

Influence of Angles of Shighting and the Earth's Surface Curvature on the Spatial Resolution of the Space Electro-Optical Viewing System

Background. One of the key differences between the aeronautical and space optical-electronic viewing systems (OEVS) of remote sensing of the Earth is the height from which the Earth's surface picture is taken. The difference between the heights of aircraft and spacecraft devises can reach several orders of magnitude, so if for aeronautical OEVS you can calculate spatial division on a plane, then for space OEVS this is critical and it is necessary to additionally consider the Earth's surface curvature, especially for angles of sighting other than zero.Objective. The aim of the paper is to develop physico-mathematical model for determining the resolution of the OEVS, which considers the Earth's surface curvature, the orbital height and location of the spacecraft position for different angles of shighting.Methods. In the basis of physical and mathematical model is proposed to use a biaxial ellipsoid as an approximation of the Earth shape to determine its surface curvature and Sun-synchronous orbit trajectory.Results. Practical results of the calculations prove that the Earth's surface curvature for space OEVS significantly influence the spatial resolution and differs from the results obtained by physical and mathematical model in which the spatial resolution is determined on a flat surface. The results of the design show, that when deflected at the angles of shighting, it is necessary to consider the additional deflection in calculations, which it increases, when distance increases for the nadir. At maximum angles of sight, pitch and roll to ±35º, i.e. when the OEVS is deflected at 44.7º from the nadir, the additional deflection is 6.3º, which significantly influences the determination of spatial resolution.Conclusions. The analysis of the proposed the physico-mathematical model of the OEVS showed that the Earth's surface curvature orbit trajectory and the location of the spacecraft, unlike the height, influence the pixels’ projection shape deformation. In this case, the values of the projection tilt angles of the rows and columns of the matrix detector relative to the flight direction change nonlinearly, which adversely influence the system modulation transfer function and require the calibration for some parameters during the flight depending on the angles of shighting and location coordinates.

A comprehensive model for x-ray projection imaging system efficiency and image quality characterization in the presence of scattered radiation

This work proposes a method for assessing the detective quantum efficiency (DQE) of radiographic imaging systems that include both the x-ray detector and the antiscatter device. Cascaded linear analysis of the antiscatter device efficiency (DQEASD) with the x-ray detector DQE is used to develop a metric of system efficiency (DQEsys); the new metric is then related to the existing system efficiency parameters of effective DQE (eDQE) and generalized DQE (gDQE). The effect of scatter on signal transfer was modelled through its point spread function (PSF), leading to an x-ray beam transfer function (BTF) that multiplies with the classical presampling modulation transfer function (MTF) to give the system MTF. Expressions are then derived for the influence of scattered radiation on signal-difference to noise ratio (SDNR) and contrast-detail (c-d) detectability.The DQEsys metric was tested using two digital mammography systems, for eight x-ray beams (four with and four without scatter), matched in terms of effective energy. The model was validated through measurements of contrast, SDNR and MTF for poly(methyl)methacrylate thicknesses covering the range of scatter fractions expected in mammography. The metric also successfully predicted changes in c-d detectability for different scatter conditions. Scatter fractions for the four beams with scatter were established with the beam stop method using an extrapolation function derived from the scatter PSF, and validated through Monte Carlo (MC) simulations. Low-frequency drop of the MTF from scatter was compared to both theory and MC calculations. DQEsys successfully quantified the influence of the grid on SDNR and accurately gave the break-even object thickness at which system efficiency was improved by the grid. The DQEsys metric is proposed as an extension of current detector characterization methods to include a performance evaluation in the presence of scattered radiation, with an antiscatter device in place.