HistScaleImg
DESCRIPTION
Performs histogram scaling of an image.
A certain specified percentage of the high intensity points is clipped
to a specified clamp value. Similarly a certain specified percentage
of the low intensity points is clipped to a specified clamp value.
The intervening intensities are linearly scaled between the two
specified clamp levels. This operation can be used to enhance the
contrast of an image. Histogram scaling is discussed in:
Digital Image Processing, Gonzales, R.C., Wintz, P.,
Addison Wesley, Second Edition, 1987, pp 144--160.
INPUTS
Port: Img In
Type: Lattice
Constraints: 1..3-D.
source image
WIDGETS
Port: High Out
Type: Dial
percentage of high values to clip
Port: Low Out
Type: Dial
percentage of low values to clip
Port: High Clip
Type: Slider
high clipping value
Port: Low Clip
Type: Slider
low clipping value
OUTPUTS
Port: Img Out
Type: Lattice
Constraints: 1..3-D.
clipped and scaled image
PROBLEMS
When clipping 100% of the high values to a High Clip value of 255, some
RGB byte images are not entirely clipped to white (all channels 255). In
the observed case, the area not clipped is a few percent of the total image
area.
SEE ALSO
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© The Numerical Algorithms Group Ltd,
Oxford UK. 1996