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Region Morphology vTool#

The Region Morphology vTool allows you to modify the shapes and sizes of regions.

You can reduce or expand regions, remove small structures, remove holes, or fill holes. This ensures that subsequent processing is more efficient or delivers better results.

The Region Morphology vTool accepts regions or region arrays via the Regions input pin and outputs region arrays via the Regions output pin.

Region Morphology vTool

运作原理#

The purpose of region morphology is the manipulation of regions. The basic morphology operations Erosion and Dilation are based on a region mask. Circular and rectangular masks are available, and you can specify their sizes (radius / width and height). Both masks are symmetrical with a well-defined center.

The following morphology operations are available:

  • Opening: This removes small structures that are smaller than the mask from the region. Basically, this is an Erosion followed by Dilation. The region is more or less the same size and shape as before.
  • Closing: This fills or bridges gaps that are smaller than the mask in the region. Basically, this is a Dilation followed by Erosion. The region is more or less the same size and shape as before.
  • Erosion: This reduces the area of the region based on the mask settings.
  • Dilation: This expands the area of the region based on the mask settings.
  • Fill: This fills holes within the region. This operation doesn't require a mask.

In addition to the options listed above, you can also perform region splitting. This turns connected components of a region into separate regions. If you select the corresponding check box, the connected components of all single or multiple input regions are computed.

A connected component is a region where all pixels have a direct neighboring pixel (in horizontal, vertical, and diagonal direction). Regions that are not connected will be split into individual output regions.

You can also perform region splitting on the raw input region without any morphology operation before.

信息

If you're using region morphology as part of a blob analysis, you can concatenate multiple Region Morphology vTools in order to compute the desired output region at the end.

Depending on the goal of the blob analysis, you may use the Region Selection vTool as an intermediate or final step in a series of region morphology operations to filter out just the relevant regions.

示例#

The following sections illustrate the different morphology operations using sample images.

Erosion and Dilation#

The following images show you how to use two morphology operations (Erosion and Dilation) consecutively to separate touching objects while retaining their original shapes. As a result, the number of objects can be counted properly, potentially followed by an inspection based on region features.

This is the input image showing white tablets:

Region Morphology vTool Input Image

This is the image with the initial regions found, e.g., after color classification:

Region Morphology vTool Example Erosion / Dilation Original Image

After applying an Erosion operation, the regions look like this:

Region Morphology vTool Example Erosion / Dilation Original Step Erosion

Finally, after applying a Dilation operation, the tablets are separated.

Region Morphology vTool Example Erosion / Dilation Original Step Dilation

Opening and Fill#

The Opening operation is often used to suppress small regions, e.g., resulting from image noise or clutter, which results in an imperfectly segmented region. In other words, Opening can be used to filter out significantly large region structures by using an appropriate mask.

The following images show that by opening a region with a circular mask of approximately half the size of the target object the fiducials of a circuit board can be detected.

Region filling is used as an intermediate step to turn the rings into filled circles.

This is the input image showing a circuit board:

Region Morphology vTool Example Opening Original Image

Using thresholding, the light structures in the image can be seen in the output regions:

Region Morphology vTool Example Opening Thresholding

After applying the Filling, the rings are filled:

Region Morphology vTool Example Opening Filling

Finally, applying the Opening will eliminate all small regions and leaves only the fiducials as detected regions:

Region Morphology vTool Example Opening Result

Closing#

The Closing operation is basically used to close indentations in regions, fill gaps, or join individual region segments.

Based on the same circuit board example as before, this example shows how to segment the ball grid array regions. The starting point is the thresholded image showing the light structures shown above.

Apply a Closing with a rectangular mask big enough to bridge the gaps between all the balls of the ball grid array.

Region Morphology vTool Example Closing Result

Apply an Opening to reduce small unwanted regions.

Region Morphology vTool Example Closing Result

Finally, use the Region Selection vTool to select both ball grid array regions based to their size.

Region Morphology vTool Example Closing Result

Common Use Cases#

  • Shrinking regions by using circular or rectangular Erosion
  • Expanding regions by using circular or rectangular Dilation
  • Removing small objects by using Opening
  • Filtering out bigger objects by using Opening with an appropriate mask shape
  • Filling small holes or indentations by using Closing
  • Bridging gaps between regions by using Closing
  • Filling holes within regions by using Fill
  • Computing connected regions splitting them by using Region Splitting in order to count the number of regions

Configuring the vTool#

To configure the Region Morphology vTool:

Region Morphology vTool Settings

  1. In the Recipe Management pane in the vTool Settings area, click Open Settings or double-click the vTool.
    The Region Morphology dialog opens.
  2. In the Morphology Operation area, select the operation you want to carry out.
    If you only want to split regions without performing any morphology operations, select Off.
  3. In the Mask Shape area, select the shape and the size of the mask.
    A mask is required for the Erosion, Dilation, Closing, and Opening operations.
  4. In the Region Splitting area, specify whether you want to split the connected components of a region into separate regions.
    Splitting can also be used directly on the input image without performing any morphology operations first.

You can view the result of the morphology operation in a pin data view. Here, you can select which outputs to display.

Inputs#

Regions#

Accepts a single or multiple regions.

  • Data type: Region, Region Array

Outputs#

Regions#

Returns a single or multiple processed regions.

  • Data type: Region Array

Typical Predecessors#

Typical Successors#

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