The Area of Interest (AOI) drawing tools are used for including or excluding certain areas from analysis and modification, or to define pixels as void pixels. The AOI Toolbar is shown below:
This tool key toggles between include and exclude mode. In the include mode the area inside the drawn shapes are included while the exterior is excluded. The excluded area will be shown in a slightly modified colors defined by the AOI View Settings. Selected AOI shapes can be toggled between include and exclude mode by clicking this tool key.
The Rectangular AOI tool key is used for drawing rectangular shapes. To create at quadratic shapes keep the Shift key down while drawing.
The Elliptical AOI tool key is used for drawing elliptical shapes. To create circular shapes keep the Shift key down while drawing.
The Polygon AOI tool key is used for drawing any shape in free hand. The drawing is performed by clicking the mouse at desired points or just by moving the mouse while keeping the left mouse key down. The drawing will finish when clicking the right mouse button.
You can use the Clear All AOIs button to clear all defined AOI shapes at once or delete individual AOI shapes using the Delete key.
To select a drawn AOI shape click the Selection tool key and the click on the desired AOI shape. To select close together or overlapping AOI shapes it may be practical to use the Tab button to select the individual shapes
An active AOU shape can conveniently be duplicated by pressing Shift+Ctrl+D
Example on how to create a donut like AOI
If you want to combine AOI markers to create at more complex shape such as the donut like shape do the following:
First, place the larger AOI circle of the donut, and set this to exclude the interior area (the interior of the circle is shaded). Then place a smaller AOI circle inside the first, and set this to include the interior area. You have now created a donut AOI.
You can modify the appearance of the AOI and the excluded region from the view settings connected to the image window. The settings are seen in the Image section:
You may modify the color, line width, Line style and transparency of the excluded area and define your own default style.
The context menu of AOI shapes can in addition to the previously described functions be used for defining AOI’s as being Void Pixels in such case these pixels will not be included in roughness analysis or plane correction even when the AOI shapes has been removed. Likewise void pixels may be set to appear invisible in 2D and 3D images.
In the following are a number of examples on how the AOI facilities can be applied it does not cover all possibilities but the intension is to give inspiration to the use of the AOI facilities.
When performing plane correction you might want to eliminate certain areas from influencing the result. This may for example be the case for surfaces dominated by indentations or particles. The following case demonstrates how the plane correction can be improved by rejecting an indentation area from the AOI. Top left is seen the original image and to the right is show the plane corrected image performed by subtracting a 3rd order polynomial fit the entire image. It is seen that the plane correction has created an undesired bow at the top surface because the algorithm tries to fit a function that applies also to the indentation. Below is seen the result when excluding the indentation from the AOI and it is seen that the top layer now is much flatter. Note, that when using the Quality Optimized option in the Plane Correction dialog SPIP™ will automatically exclude the indentation area when fitting a surface function.
To achieve the best color contrast with a certain area of an image you can set the “AOI Color Scale” setting on in the view setting. When changing the AOI the colors will automatically adopt the new area. You may move the AOI with the mouse or arrow keys and this way find it as useful inspection tool.
Below is seen the same image shown without and with AOI color adaptation. In the right image the indentation area is excluded from the AOI so that the color range matches to top level.
The height distribution may be very different within different area of an image and you can use the AOI tool to investigate the local height distribution. You only need to activate the histogram window and the histogram will always reflect the defined AOI.
The three pair of images below illustrates how the histogram reflects the defined AOI.
If you want restrict filtering to a specific area you can do this by defining an AOI. The below example shows the result (middle image) of a median filter performed only within the AOI. The most right image is the difference image between the original and the filter result image.
Grain Analysis can also be restricted to a defined AOI as shown below, where the top image pair shows the result without use of AOI and the bottom pair the results with a defined AOI.
Sometime distortions or contamination in an image may complicate Fourier analysis and make it difficult to find and characterize the Fourier peaks associated with at lattice structure. The below example shows how the Fourier peaks are much more apparent when eliminating the distorted area from the Fourier analysis by excluding it outside the AOI.
In addition to the above examples you may use it in most analysis and correction function such as: