Anyhow, the automatic ROI functionality in Quick MTF is almost able to work with the simulated Imatest charts I produced with mtf_generate_rectangle. I had to manually adjust about half of the ROIs to ensure that Quick MTF was using as much of each edge as possible, i.e., similar ROIs to what Imatest and MTF Mapper used. Since the edge locations remain the same across all the test images, I used the "open with the same ROI" option to keep the experiment as fair as possible.
I also discovered that QuickMTF's "trial" limit of 40 tests can be bypassed with relatively little fuss (Oleg, if you are reading this, I promise not to share the secret).
Lastly, note that I performed these tests using the "ISO 12233" mode of Quick MTF. The default settings produces much smoother plots, but these are severely biased, i.e., they report MTF50 values that are much too low. To illustrate: the default settings produce a 95th percentile relative error of 13% when measured using images with an expected MTF50 of 0.25 c/p; switching to ISO 12233 mode reduces the error to only 5%. As expected, the standard deviation of MTF50 error is lower in the default mode, but I maintain that bias and variance should both be managed well.
|Figure 1: Quick MTF MTF50 relative error boxplot|
|Figure 2: Standard deviation of relative MTF50 error|
|Figure 3: 95th percentile of relative MTF50 error magnitude|
The values in Figure 3 have a natural interpretation: the magnitude of the error will remain below the indicated value in about 95% of the edges measured with each tool. This measure combines the effects of bias (Figure 1) and variance (Figure 2) in one convenient value. Consider again the "usable" range of 0.08 to 0.5 c/p: Quick MTF only manages to keep the error below about 9% across the range. It does quite a bit better in the centre of the range, almost matching Imatest at 0.2 c/p.
ConclusionThe Imatest results were not based on the latest version; I do not have an Imatest license, and my trial has expired, so it will take a fair bit of effort to refresh the Imatest results. The Quick MTF 2.09 results are current, though.
Based on these versions, it would appear that MTF Mapper still produces competitive results. And you cannot beat MTF Mapper's price.
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