Posted by
Stein Rørvik on
Mar 30, 2019; 7:04pm
URL: http://imagej.273.s1.nabble.com/Unable-to-set-min-max-values-correctly-on-density-calibrated-8-bit-images-tp5021954.html
There is a small bug when using the setMinAndMax(min,max) function for some density calibrated 8-bit images.
When using resetMinAndMax(), the min-max range is correctly set to the minimum / maximum value.
But when using setMinAndMax(min,max) with the same values, the result min,max values are lower.
This seems to be due to a round-off error as the latter case corresponds to a 0..254 range instead of 0..255
If you change the calibrated max value to 69300 in the below example it works as it should.
Demo macro:
--------------------------------------------------
print("\\Clear");
run("Blobs (25K)");
run("Calibrate...", "function=[Straight Line] unit=[Gray Value] text1=[0 255] text2=[0 69400]"); //set rescale slope on full range
resetMinAndMax();
getMinAndMax(min,max); //0 69400
print("case 1: ", bitDepth,min,max);
setMinAndMax(min,max); //0 69400
getMinAndMax(min,max); //0 69127.8431 = (69400/255)*254
print("case 2: ", bitDepth,min,max);
--------------------------------------------------
The same behaviour is seen when using the GUI:
B&C -> Reset => range 0..69400
B&C -> Set (0, 69400) => range 0..69127.8431
I am using daily build ImageJ 1.52o with Java 1.6 on Windows 7/64-bit.
Stein
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