on some images, the slider does not show the complete gray value range that is present in the image. see attached screenshot --> pixel value on cross position is 2889, level window slider has a maximum of ~820.
Test Dataset is available at /home/jochen/temp/levelwindow-bug.pic.gz
If you want to use all intensities you can right click on the slider and select use whole image gray values. In that way the range of the slider is determined by the whole images. I believe that otherwise, in order to to speed up the process, just a part (maybe one slice) of the image is used.
Does anyone know more about the reasons for this and whether it is really necessary? It is also a bit confusing maybe.
Not a bug.
The level window is initialized by the middle slice, middle timestep and middle channel. This makes the initial value setting faster by NumberOfSlices*NumberOfTimesteps*NumberOfChannels.
Like Thomas said, to get the whole range, right click the widget and choose "Use Whole Image Greyvalues". On software side, the behaviour can be controlled via the variable "bool guessByCentralSlice" in the SetAuto() method.