The tilt of the squares facilitates measurement of Lateral Chromatic Aberration using vertical edges (which are near-tangential) near the corners. 4x7, 5x7, 5x9 and 7x11 (row x columns) grids are available. A grid of slanted squares with contrasts no greater than 10:1.Bars at the top and bottom used for measuring distortion and facilitating edge detection.The essential features of the SFRplus chart are Sharpness is derived from light/dark slanted edges at the boundaries of the squares, as described in Sharpness: What is it and how is it measured? SFRplus can handle a wide range of camera aspect ratios the left and right sides of the chart may extend beyond the frame or be well inside it. Standard SFRplus test chart: 5x9 grid, 4:1 contrast,Ģ0-step 4x5 stepchart (0.1 density increment) and color chart Results are described in more detail in Part 3 and Part 4.Ī standard SFRplus test chart (one of many configurations) is shown below. Part 3 and Part 4 illustrates the results.Ĭlick on any of the thumbnails below (or on the image itself, repeatedly) to explore the many capabilities of SFRplus. Part 2 shows how to run SFRplus inside Rescharts and how to save settings for automated runs. This document introduces SFRplus and explains how to obtain and photograph the chart. Auto mode works with large batches of files, and is especially useful for automated testing, where framing may vary from image to image. This allows images with different sizes and framing to be analyzed with no change of settings. ROIs are located automatically based on settings saved from the interactive/setup mode. Auto mode (run by pressing SFRplus Auto in the Imatest main window), which runs automatically with no additional user input.Interactive/setup mode (run by pressing Rescharts or SFRplus Setup in the Imatest main window), which allows you to select settings and interactively examine results in detail.Īll Rescharts ( Interactive/Setup) modules can read imagesįrom image files ( raw and interchangeable) ♦ via direct data acquisition from a variety of devices.SFRplus Distortion and Field of View measurements - Introduction – Pre-distorted charts – Running SFRplus & Algorithm – Results – Distortion correction display – Radial plot Using Rescharts slanted-edge modules Part 2 - Selecting files – Setup window – ROI selection & analysis – Edge ID files – More settings window – Secondary readout – Settings area – Gamma – Gamma from chart contrast ratio – Auto mode window – Warnings – Clipping – Summary ISO sensitivity (Saturation-based and Standard Output Sensitivity), when incident lux is entered.Color accuracy, when used with an SFRplus chart that contains the optional color pattern, located above the central square,.Tonal response (with less detail than Stepchart limited noise statistics),.Distortion Details in SFRplus Distortion and Field of View measurements,.Noise (limited: eSFR ISO has more detailed noise calculations),.Sharpness, expressed as Spatial Frequency Response (SFR), also known as Modulation Transfer Function (MTF), which can be mapped over the entire image,. The user does not need to manually select Regions of Interest (ROIs). Imatest SFRplus performs highly automated measurements of several key image quality factors using a specially-designed test chart that may be purchased from the Imatest store (recommended) or printed on a high-quality inkjet printer. Purchase SFRplus Test Charts from the Imatest Store.
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