Morphological Transformations

Function

This Step processes an image using morphological operations.

Usage Scenario

This Step is usually used for image pre-processing when the quality of images is not ideal and further adjustment is needed.

Apply operations such as dilation, erosion, and opening and closing to denoise, fill, etc. based on actual requirements.

Input and Output

When ClosingOperator is selected, the input and output are as shown in the figure below.

Parameter Description

Morphological Transformations

Description: This parameter is used to choose the type of morphological transformation.

Default setting: DilateOperator

List of options: ClosingOperator, DilateOperator, ErodeOperator, OpeningOperator, Skeleton

Instruction:

1. ClosingOperator: Closing is reverse of Opening, Dilation followed by Erosion. It is useful in closing small holes inside the foreground objects, or small black points on the object.

   Kernel Size

   Default setting: 21 pixel

   Instruction: The size of the kernel should be set according to the measurement requirements. The figure below shows the effect when the kernel size is set differently (smallest on the left and largest on the right). See the specific result in Configuration Example.

   Kernel Shape

   Default setting: Rectangle (MORPH_RECT)

   Options: Rectangle (MORPH_RECT), Cross shape (MORPH_CROSS), Ellipse (MORPH_ELLIPSE)

   Instruction: It is recommended to keep the default setting. However, you may configure the setting according to specific requirements.

   • Performance on image detail restoration: MORPH_RECT < MORPH_CROSS < MORPH_ELLIPSE

   • Time required for operation: MORPH_RECT < MORPH_CROSS < MORPH_ELLIPSE

2. DilateOperator: Dilation. It is mainly used to increase the object area and join broken parts of an object.

   Kernel Size

   Default setting: 3 pixel

   Instruction: The size of the kernel should be set according to the measurement requirements. The larger the kernel size, the more dilated the object area. The figure below shows the effect when the kernel size is set differently (smallest on the left and largest on the right). See the specific result in Configuration Example.

   Kernel Shape

   Default setting: Rectangle (MORPH_RECT)

   Options: Rectangle (MORPH_RECT), Cross shape (MORPH_CROSS), Ellipse (MORPH_ELLIPSE)

   Instruction: It is recommended to keep the default setting. However, you may configure the setting according to specific requirements.

   • Performance on image detail restoration: MORPH_RECT < MORPH_CROSS < MORPH_ELLIPSE

   • Time required for operation: MORPH_RECT < MORPH_CROSS < MORPH_ELLIPSE

3. ErodeOperator: Erosion. It is mainly used to remove small noises and detach two connected objects.

   Kernel Size

   Default setting: 3 pixel

   Instruction: The size of the kernel should be set according to the measurement requirements. The larger the kernel size, the greater the erosion of the object area. The figure below shows the effect when the kernel size is set differently (smallest on the left and largest on the right). See the specific result in Configuration Example.

   Kernel Shape

   Default setting: Rectangle (MORPH_RECT)

   Options: Rectangle (MORPH_RECT), Cross shape (MORPH_CROSS), Ellipse (MORPH_ELLIPSE)

   Instruction: It is recommended to keep the default setting. However, you may configure the setting according to specific requirements.

   • Performance on image detail restoration: MORPH_RECT < MORPH_CROSS < MORPH_ELLIPSE

   • Time required for operation: MORPH_RECT < MORPH_CROSS < MORPH_ELLIPSE

4. OpeningOperator: Opening is another name of erosion followed by dilation. It is useful in removing noise.

   Kernel Size

   Default setting: 21 pixel

   Instruction: The size of the kernel should be set according to the measurement requirements. The figure below shows the effect when the kernel size is set differently (smallest on the left and largest on the right). See the specific result in Configuration Example.

   Kernel Shape

   Default setting: Rectangle (MORPH_RECT)

   Options: Rectangle (MORPH_RECT), Cross shape (MORPH_CROSS), Ellipse (MORPH_ELLIPSE)

   Instruction: It is recommended to keep the default setting. However, you may configure the setting according to specific requirements.

   • Performance on image detail restoration: MORPH_RECT < MORPH_CROSS < MORPH_ELLIPSE

   • Time required for operation: MORPH_RECT < MORPH_CROSS < MORPH_ELLIPSE

5. Skeleton: Extract the contour of the object.

Configuration Example

ClosingOperator

When ClosingOperator is selected, the size increase of the kernel is shown in the images below (The kernel size grows by degrees and from image 1 to 3):

DilateOperator

When DilateOperator is selected, the size increase of the kernel is shown in the images below (The kernel size grows by degrees and from image 1 to 3):

ErodeOperator

When ErodeOperator is selected, the size increase of the kernel is shown in the images below (The kernel size grows by degrees and from image 1 to 3):

OpeningOperator

When OpeningOperator is selected, the size increase of the kernel is shown in the images below (The kernel size grows by degrees and from image 1 to 3):

Skeleton

The images before and after Skeleton is selected are as follows: