Stretches contrast on the image and normalize image from 0 to 1

The main difference of this function to the standard streching functions is that

standard function finds global minimum and maximum on the image, then uses

some low and high threshold values to normalize image(values below LowTHR are

equated to LowTHR and values above HighTHR are equated to HighTHR). This function

uses threshold values that are NEXT to miminum and maximum. Thus, we can exclude

image backgound (which is normally zero) and find minimum value on the image itself.

Same consideration goes to high thr. We exclude first global maximum because, if its

a spike, we have better chance with the next value, and if it is not a spike, normally,

next value is quite close to max (assuming smooth image), so our error is sma- Stretches contrast on the image and normalize image from 0 to 1

　The main difference of this function to the standard streching functions is that

　standard function finds global minimum and maximum on the image, then uses

　some low and high threshold values to normalize image(values below LowTHR are

　equated to LowTHR and values above HighTHR are equated to HighTHR). This function

　uses threshold values that are NEXT to miminum and maximum. Thus, we can exclude

　image backgound (which is normally zero) and find minimum value on the image itself.

　Same consideration goes to high thr. We exclude first global maximum because, if its

　a spike, we have better chance with the next value, and if it is not a spike, normally,

　 next value is quite close to max (assuming smooth image), so our error is small