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Stephen Minne replied on Mon, Apr 18 2011 4:21 PM

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Suggested by Bede Pittenger

Iwei,

The help section for Particle Analysis is very good (go to Help -> Help, and search Particle Analysis), and I think should answer your questions. I have also copied it below. If not, can you post your file and settings?

Thanks,

Steve

Particle Analysis

The Particle Analysis command defines features of interest based on the height of pixel data. This command was designed for analyzing well isolated particles or features of interest. Particles may be analyzed singly or in quantities. Particles in this context, are conjoined pixels above or below a given threshold height.

The analysis includes a histogram of particle size, which can be used to identify specific particles by size. Measurements on this analysis include: the mean area and standard deviation of the particle sizes, the total number of particles, a correlation histogram, and a depth histogram.

The figure below illustrates how particles can be isolated by height. This type of analysis works well on materials in which particle size or type is linked to height.

Dilate & Erode 

As applied to the Particle Analysis command on NanoScope Analysis images, Dilate is used to clump grains together and Erode is used to separate grains. Pixels comprising an image are evaluated in square matrices (i.e., neighborhoods), sized according to the Neighborhood Size and Number Pixels Off parameters. Executing Dilate will increase the size of particles. Conversely, executing Erode will decrease the size of particles.

Dilate—The effect of digital dilation is to conjoin otherwise separate grains, and to mend broken grains. If the Number Pixels Off for Dilate parameter is set to 1, the dilation process is triggered if even one pixel is off, making dilation more sensitive at a setting of 1. Furthermore, if the Dilate Neighborhood Size is large, dilation is applied to larger areas of the image. Therefore, maximum dilation is attained with a large Dilate Neighborhood Size setting and a small Number Pixels Off for Dilate setting. Minimum dilation is attained with a small Dilate Neighborhood Size setting and a large Number Pixels Off for Dilate setting.

Erode—The effect of digital erosion is to separate grains which otherwise touch or conjoin one another. If the Number Pixels Off for Erode parameter is set to 1, the erosion process is triggered if even one pixel is off, making erosion more sensitive at a setting of 1. Furthermore, if the Erode Neighborhood Size is large, erosion is applied to larger areas of the image. Therefore, maximum erosion is obtained with a large Erode Neighborhood Size setting and a small Number Pixels Off for Erode setting. Minimum erosion is attained with a small Erode Neighborhood Size setting and a large Number Pixels Off for Erode setting. 

Particle Analysis Procedure

The Particle Analysis command is designed to detect and measure the lateral and vertical dimensions of isolated particles on the sample surfaces. The procedure for using Particle Analysis is as follows:

1. Open an image in NanoScope Analysis.
2. Select Analysis > Particle Analysis from the Menu bar or click on the Particle Analysis icon from the Icon toolbar. The file opens in the Particle Analysis window with the Detect tab showing.

1. Choose Above or Below from the Feature Direction parameter in the Detect tab. If the interested features are above the surface, choose Above. If they are below the surface, for example pits, choose Below.
2. Adjust the threshold by moving the red vertical cursor in the Depth Histogram to the preferred location (usually between the two most defined peaks). The particles (features of interest) will turn to sky blue in the Particle Analysis window. Data for the selected particles is captured at the bottom of the window in the Detect tab Data Box.
3. When satisfied with the particles selected in the Particle Analysis window, click the Next button at the bottom of the Detect tab. NanoScope Analysis opens the Modify tab.

1. Adjust the Erode and Dilate parameters as preferred. For details on the Erode and Dilate parameters, please click on the following link: Dilate & Erode. Once completed, click on the Next button. NanoScope Analysis opens the Select tab.

1. Modify the Select tab parameters to get the desired results. For details on the Select tab parameters, click on the following link Select Tab Parameters. The Select tab also contains 3 histograms: Diameter, Height, and Area. Each histogram provides a different way to analyze particles. Slide the cursor laterally along the bottom of each histogram to highlight each particle plotted. The corresponding data for each particle is displayed in the Data Box at the bottom of the window.

Particle Analysis Interface

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