How to optimize measures of areas, deviation standards on other statistics using pixel thresholds on 2D surfaces?
You can modify the pixel thresholds in 2D surfaces: ellipse, polygon, rectangle and pen.
Use of the minimum and maximum threshold:
- Create a 2D surface: a polygon, a pen, a rectangle or an ellipse.
- Mark the "Display" check box of the annotation. This will add a colored layer inside the 2D surface (see below with the "pen" object). This layer marks the pixels in the annotation, which belong to the range defined by the minimum and the maximum threshold.
- Mark the "Min Threshold" check box.
- In the "Min Threshold" edit box, type the minimum threshold value and hit the 'Enter' key.
Note that the surface area, min/max, total, mean and standard deviation values have been affected by the new minimum threshold. Some pixels in the 2D surface are also no more in the green layer.
You can modify the minimum threshold in a more interactive way by following these instructions:
- Keep your mouse cursor in the "Min Threshold" edit box, press the right button of the mouse and hold it.
- While holding the right button, drag your mouse in the left direction to decrease the threshold value or in the right direction to increase it. As you drag, you can see the green layer and values affected in real-time.
- Release the right button of the mouse.
Note:
- To use the maximum threshold value, please follow the same instructions than for the minimum threshold.
- When you use the minimum or maximum threshold value, the calculation of the surface area will be based on the pixel surface area unit. When not, the calculation of the surface area is based on the real size of the freehand polygon. Both values may differ a little.
- You can modify the color of the layer in the preferences panel.
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