[Exercises]
[Workspace]
Purpose:
The purpose of this lab is to experiment with the window
and level technique for image contrast enhancement.
Activities:
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Determine statistical information for a given data set and
calculate the histogram.
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Select the image $DIP/data/spine.kdf and display it using
operators User defined and Display Image.
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Glyphs:Input/Output:Data Files:User defined
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Glyphs:Visualization:Non-Interactive Display:Display Image
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Determine the maximum and minimum values in the image using the
operators Statistics and File Viewer.
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Glyphs:Data Manip:Analysis & Information:Statistics
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Glyphs:Input/Output:Information:File Viewer
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Open the Statistics pane and select the "minimum" and
"maximum" options.
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Connect the operators and run the network.
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Obtain the histogram and plot it. Use operators Histogram and Display 2D Plot.
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Glyphs:Data Manip:Histogram Operators:Histogram
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Glyphs:Visualization:Plot Display:Display 2D Plot
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Open the Histogram pane and set the "Number of bins" and
"Minimum" parameters using the maximum and minimum values determined
in the previous step.
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Apply the Window and Level technique.
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From the histogram, choose an "Intensity of Interest (IOI)"
range. A set of good values for this image range from 1050 to
1150. This gives a window of 100.
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First clip the intensity value outside the desired range using
the operator Clip Outside.
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Glyphs:Data Manip:Threshold & Clip Operators:Clip Outside
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Open the Clip Outside pane and set the cutoff values to be
the lower and upper values determined in step A.
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Normalize the image (0 to 255) using the Normalize operator
and display the results.
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Glyphs:Data Manip:Data Conversion:Normalize
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Glyphs:Visualization:Non-Interactive Display:Display Image
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You can interactively enhance the image using this "window and level"
technique by using the Edit Image glyph.
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Glyphs:Visualization:Interactive Display:Edit Image
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Click on the "Threshold" option to show the threshold pane
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Select "Window Contrast Enhancement" in the Threshold window
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Drag with the mouse the "Upper" horizontal scrooling bar to
dinamically change the windown and level enhancement parameters applied
to the image.
Exercises
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Experiment by changing the "Window" and "Level" parameters.
Khoros Workspace
Execute the visual program c4s3window-level.wk
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