Friday, 25 November 2016

MTF Mapper finally gets a logo!

It is a sad day for command line enthusiasts, but MTF Mapper has finally conformed by adopting a logo for its GUI version.

I guess in the world of graphical user interfaces, a logo is to an application what a flag is to a nation (cue the Eddie Izzard reference).

There is of course a new version of MTF Mapper (0.5.11 or later) available over on SourceForge. Lots of fixes and cleanup to the GUI; please let me know what you think of the new(ish) interface.

Monday, 13 June 2016

Running MTF Mapper under Wine

MTF Mapper 0.5.2 was compiled using MSVC Express 2013, which Microsoft calls "vc12". The Windows binaries have been linked statically against the runtime, but this does not appear to be sufficient to run MTF Mapper under wine without further tweaks.

For me, running "winetricks vcrun2013" in the console seemed to do the trick. I would say that this is a necessary step to get MTF Mapper to work under wine.

In case you are wondering, without the winetricks step I get the following error:
wine: Call from 0x7b83c506 to unimplemented function msvcr120.dll.?_Trace_ppl_function@Concurrency@@YAXABU_GUID@@EW4ConcRT_EventType@1@@Z, aborting

Let me know if there are any other issues related to wine, and I'll see what I can do.

Wednesday, 13 April 2016

MTF Mapper vs Imatest vs Quick MTF

I recently noticed that Quick MTF now has an automated region-of-interest (ROI) detection function. This allows me (in theory) to perform the same type of automated testing that I applied to MTF Mapper and Imatest. Now would be a good time to read the Imatest comparison post to familiarise yourself with my testing procedure.

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.

The results

Figure 1: Quick MTF MTF50 relative error boxplot
Figure 1 illustrates the relative MTF50 error boxplot, calculated as 100*(measured_mtf50 - expected_mtf50)/expected_mtf50. Firstly, Quick MTF should be commended for its unbiased performance between expected MTF50 values of 0.1 and 0.4 cycles/pixel; the median error is exactly zero. Unfortunately, a strong bias appears after 0.4 c/p, which is consistent with some (light) smoothing of the ESF. The boxes, and especially the whiskers, are a bit wide, which is more readily seen in Figure 2.

Figure 2: Standard deviation of relative MTF50 error
Things go a bit pear shaped when we look at the standard deviation of the relative MTF50 error. If we consider the "usable" range of 0.08 to 0.5 c/p, then Quick MTF contains the standard deviation below 3.5%, which is not bad, but Imatest and MTF Mapper perform a bit better here. A more useful (and my preferred) measure is the 95th percentile of relative MTF50 error magnitude, as illustrated in Figure 3.
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.


The 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.