Thresholding methods inconsistent

[johnp65339284]

Recently upgraded to Photoshop Elements 2019 on Windows 10.

This site Adjustment filters  lists several thresholding methods.  Method 1:  Filter > Adjustments > Threshold and Method 2:  Layer > New Adjustment Layer > Threshold provide different results.  I am using a calibrated image with threshold = 128 verified through Matlab.  From the results, Method 2 is the more accurate filter method.  Any ideas/reasons behind the difference in Methods? 

B&W   Closure [%]
Matlab	PElements  filter	PElements  layer
99.04	99.74	99.1
95.08	98.65	95.31
90.16	97.3	90.65
85.29	95.94	86.01

[Jeff Arola]

In theory it shouldn't make any difference, except if the layer has transparency and that would make the threshold

adjustment layer act different (less accurate) than the pixel threshold adjustment.

Does it make any difference in your results if you clip the threshold adjustment layer to your test layer?

That is with the threshold adjustment layer created and active in the layers panel go to Layer>Create Clipping Mask

then see if that makes a different in the test results.

Have you tried this on any previous versions of photoshop elements?

[johnp65339284]

The layer is fully transparent as the adjustment threshold mask is fully opaque (100% is the default).  If I've followed your instructions correctly, clipping the threshold adjustment layer does not affect results, which I believe is expected considering 100% opacity. 

The Filter > Adjustments > Threshold method was run previously on Elements 5 and the results are in-line with Elements 2019 Layer > New Adjustment Layer > Threshold method.