Grain Analysis

Introduction

The Grain Analysis module is an option for NanoRule+™ image analysis software and is useful for identifying and analyzing grains. There are several provisions for identifying grains. Once identified, many parameters such as area, perimeter, height, and length may be calculated. Several options are available for reporting the results from the grain and particle analysis. Grain boundaries can be defined using threshold levels and slope in the image. Therefore all grains will be detected at a threshold level. Two methods, “Threshold Segmentation" and "Watershed Segmentation", may be used to separate all regions at the same level.

The five steps required for counting grains in an image are:


Step 1: Prepare Your Image
Step 2: Select Grain Analysis Function
Step 3: Set The Threshold
Step 4: Search and Count Grains
Step 5: Report Grain Analysis Results

Figure 1: Grain Image measured with an AFM

Step 1: Prepare Your Image

Before doing Grain Analysis, an image must be leveled to remove any residual background tilt.



Step 2: Select Grain Analysis Function

The Grain Analysis function can be selected from menu Analysis -> Grain Analysis or with the toolbar button.

When the Grain Analysis dialog box is activated, an image with a highlight is displayed. The highlight is defined by a preset threshold level and detection mode. It may not be optimized for the current image so you may need to adjust this threshold.



Step 3: Set The Threshold

Grain Analysis Dialog Box: In the Grain Analysis Dialog Box, if the Threshold check box is selected, a defined threshold level is applied to the image.

Threshold Edit Window: The Threshold Edit Window can be opened by clicking the "Edit" button in the Threshold group. An image histogram is then displayed. A Red/Green line in the histogram window indicates the current threshold level position. The color bar has two different palettes, one is the original image palette, and one is a highlighted palette which means that all data in this range will be counted when searching for objects.

Figure 3: Screen Shot of Grain Image and Threshold Edit Window

Step 4: Search and Count Grains

Figure 4: Search Dialog Box

Count Button: After a proper threshold level is defined, the "Count" button is selected, and the grains will be counted. All counted objects are defined and highlighted.

Figure 5: Counting Object Image from Grain Analysis

Segment Option: The method for selecting segments may be modified. This is done by clicking the “Option” button in the search group. The "segment option" dialog then appears.

Figure 6: Segment Option Dialog Box

Highlight: An object can be highlighted in the following three different styles:

Figure 7: Filled and Outline	Figure 8: Outline	Figure 9: Filled

Separated by: Particles can be separated by one of two methods:

• 4-Connected: only objects that share a corner pixel will be counted separately.
• 8-Connected: objects that are connected in any way will be counted as one.

In both 4- and 8-Connected modes, the two objects are counted as one.	When 4-Connected mode is selected, they will be counted as two objects. In 8-Connected mode, they count as one.

Boundary (in pixel): Adjusts the boundary of the image to determine the inclusion of partial objects.

Figure 10: Boundaries

Smooth: Provides three different filtering kernels for pre-processing the image.


Sort By: Labels of the objects can be sorted in area, perimeter, length, or width. The number is ordered from large to small. The default is a searching order.

Sorting by area. The object will be labeled from largest area to smallest area. After finishing all changes, click the Apply button. The new segment option will affect counted objects.

Figure 11: Sorting

Show Results: After object counting, Results can be shown by checking this box:

If you select any object in the image, the single object information in above dialog box will be updated.


Settings

Minimum Grain Size	If a grain size is smaller than this grain, it won’t be counted.
Minimum Peak Distance	A peak of grain is its local maximum. So peak distance is defined as a distance between adjacent grains local maximum.
Equalization	If this box is checked, an equalization method will be applied to the image prior to counting.

Segment Edit: After counting objects, user is able to edit objects in the image.

Figure 13: Segment Edit Dialog Box

Measurement Option: With this option a user is able to choose his own parameters that are displayed in the Report Dialog Box. When an item is selected on the left side, an illustration is presented on the right side.

Figure 15: Measurement Option Dialog Box

Step 5: Report Grain Analysis Results


When the report function is selected, a Measurement Report is displayed. The report items are based on user’s selection from the Measurement Option. Sorting is available for each parameter by clicking the column header.

Plot Function: Users can generate their own set of Plot Functions. When the Modify button is selected, the Plot Function Dialog Box is shown. In the Plot Function Dialog Box, the user can choose the items from the left side to create a plot.

Figure 19: Plot and Area Screen Shots