The chart with the highest maximum spatial frequency (just outside the inner circle) is the Log Frequency-Contrast chart. The effect is pronounced on the other four charts above. (The effect is also visible on the other charts.) The Siemens star on the Slanted-edge chart has no border to reduce maximum spatial frequency, so the maximum spatial frequency of the chart is not reduced. This is because the border of the star on the Log Frequency-Contrast chart has a black bar at each end that reduces the maximum spatial frequency. The star pattern on the Log Frequency-Contrast chart is skewed, while the star on the Slanted-edge chart has an edge. As you can see in the images above, the star patterns on the Log Frequency-Contrast and Slanted-edge charts are clearly visible. The border on the other charts, including the slanted-edge chart, is blue. Siemens star shown above has a red border, which is meant to be picked when selecting the pattern to be analyzed.
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