Version 0b1.x     Bureau H. Glünder 2018

WHAT FOR

 

Horizontal Tracing is an “ImageJ”-PlugIn which is “ImageJ Macro”-recordable.

 

Horizontal Tracing traces the contours of a horizontally elongated object (dark on light ground) and represents them as polyline selections.

 

Horizontal Tracing primarily serves the determination of thickness variations of elongated and horizontally aligned objects.
According to the disc diameter of the applied "Rolling Disc"-approach, contour gaps are bridged and contours are smoothed.

 

Horizontal Tracing does not accept colour-images or image-stacks.

 

HOW TO

 

Download “HorizontalTracing_0b1-x.zip”, unzip this file, consult the ReadMe, and put Horizontal_Tracing.class in the “plugins”-folder of your “ImageJ”-distribution.

 

Quit and restart “ImageJ”.

 

Open an image showing an elongated and horizontally aligned object.

 

Create a suitable circular selection above or below the object.

 

Choose the item “Horizontal Tracing” from the “Plugins”-menu of “ImageJ”.

 

The dialog:

• Select the object contour to be traced.
• Decide on the treatment of concave contour parts.
• Enter the threshold value.
• Enter the trace length.

 

Further details:

• The elongated object must be dark on light background.
• The center of the initial circular selection (disc) defines the horizontal start position for the tracing. The vertical disc position must be above or below the object at a convenient distance from the contour to be traced.
• The threshold defines the distance, the disc enters the object during tracing. The disc stops entering if the enclosed mean value equals the threshold.
• Thickness measurements require equal lengths of the upper an lower traces, hence contours having concave parts require special treatments. Two options are available:
  "Cliff-jump", for which the tracing jumps from overhanging contours and
  "Cliff-cut", for which the tracing cuts through overhanging contours.
• The resulting polyline selection is created with sub-pixel resolution.

 

Macro operation:

• Macro code for running “Horizontal Tracing”:
  makeOval( -2.5, 0, 5, 5 ); // rolling disc
  ps = "Upper side";  cc = "Cliff-jump";  thr = 127;  len = 256; // example values
  run("Horizontal Tracing", "contour=["+ps+"] concavity="+cc+" threshold="+thr+" length="+len);

 

USE AND ABUSE

 

Horizontal Tracing requires a license.

 

Horizontal Tracing is provided AS IS and you use it entirely at your own risk.