TrainBead

The TrainBead function Functions are tools that are available in Spreadsheet for processing and analyzing acquisitions or other results. You can add functions to your Spreadsheet job to create tool chains and produce results for specific applications. allows you to locate a bead path and create measurements of the thickness and position of the bead path. These measurements provide a baseline by the InspectBead function to determine whether another, similar bead contains defects or gaps in position, width, or coverage.

Note:

The TrainBead and InspectBead functions do not support color images. If you load a color image, the functions automatically convert it to a greyscale image.
For more information about how to use the TrainBead and InspectBead functions, see How to use TrainBead and InspectBead Tools.

TrainBead Inputs

Syntax: TrainBead(Image,Fixture A fixture is a coordinate location on the image that keeps the tool in the place determined by the fixture.,Background Image,Bead Sample Location,Max Width Deviation (%),Bead Finding Tolerance,Bead Find Optimizations,Max Bead Paths to Find,Find Bead Paths,Selected Bead Path,Edit Bead Path,Bead Train Optimizations,Train Bead Path,Show Graphics)

Parameter

Description

Image

This argument must reference a spreadsheet cell that contains a valid Image data structure. By default, the cell references A0, containing the Image data structure returned by the AcquireImage function.

Fixture

Specifies the image coordinate system in which the bead path is defined. You need to connect a fixture to a PatMax tool.

The default setting is (0,0,0), the top leftmost corner of the image.

Row (default = 0)	The row offset, in image coordinates.
Column (default = 0)	The column offset, in image coordinates.
Theta (default = 0)	The angle of orientation, in the image coordinate system.

Background Image

(Optional) Specifies a reference to a spreadsheet cell that contains an Image data structure of an image to be used for image subtraction.

A background image needs to be an image without any bead material. It is used to create a high contrast image between an image with and without bead material to enhance the bead material visibility on a part during the bead find analysis.

Note:

The tool generates the subtracted image after you click the Find Bead Paths button. Check the Show Graphics Subtracted Image checkbox to see the subtracted image.
The job A job is a user-configured program in In-Sight Spreadsheet consisting of functions and designed for specific applications. You can create and edit jobs using the In-Sight Spreadsheet interface, and load them on a vision system for deployment in a live environment. does not save the subtracted image.

Bead Sample Location

Specifies where the FindBead function begins to search for bead path(s). You do not need to place the circle in the center of a bead path, as long as the radius of the circle encloses both edges of the bead.

Note: Cognex recommends that you make the radius of the circle around three times bigger than the thickest part of the bead. If the radius is too big or small, the tool fails to find a bead path, or finds an incomplete contour.

Note: The value of the Radius parameter determines the width of the search calipers. If a section of the bead is wider than the search calipers, the bead search fails.

X	The x-offset of the circle, in image coordinates (0 to sensor image height - 1; default = sensor image height / 2).
Y	The y-offset of the circle, in image coordinates (0 to sensor image width - 1; default = sensor image width / 2).
Radius	The radius of the circle, in image coordinates (0 to sensor image height / 2; default = 30).

Max Width Deviation (%)

Specifies the maximum allowable bead width change in percentage (1-100; default = 50). The bead search stops if the bead width deviation is above or below the threshold.

Bead Finding Tolerance

Specifies how aggressively to search for edges that comprise a bead (0-10; default = 3). A higher value allows bead finding to operate in areas of the image where the bead path is ambiguous.

0 = Least aggressive

...

10 = Most aggressive

Bead Find Optimizations

Specifies bead finding parameters that can be set manually or allowed to be automatically calculated by the tool.

Auto	Specifies whether or not the function automatically determines the bead finding optimization parameters.
Bead Color	Specifies the bead color against the background color (Dark on Light or Light on Dark; default = Light On Dark).
Bead Width	Specifies the expected bead width in pixels (1 to sensor image width - 1; default = 10). Note: If the average bead width within the Bead Sample Location circle is out of the range of Bead Width +/- Max Width Deviation (%), the bead search fails. For example, if the expected Bead Width is set to 12 and the Max Width Deviation (%) is set to 25%, the average bead width within the Bead Sample Location needs to range from 9 to 15. If the actual average bead width detected within the Bead Sample Location is 17, no bead path is going to be be found.
Min Contrast	Specifies the minimum contrast value (1-255; default = 10) to be considered a bead edge. A lower value allows bead edges to be detected in low contrast images with noise.

Max Bead Paths to Find

Specifies the maximum number of possible bead path candidates to find (1 - 5; default = 5). The function stops processing once the specified number of bead candidates are found.

Find Bead Path

Click this button to start finding bead path candidates.

Note: Pressing the Find Bead Paths button clears all previous bead path information including modifications to the existing paths or trained bead path data. To exit the property sheet without saving any changes, press Cancel.

Selected Bead Path

Specifies which of the possible bead path candidates is going to be used to display and to train the bead (0 to 4; default = 0).

Note: To see the updated number of candidates, after you changed the number, press Tab or select another field on the property sheet.

Bead Train Optimizations

Specifies training parameters for optimizing bead training.

Caliper Spacing	Specifies the density of the edge detection calipers that are placed along the bead path (1 - 10; default = 3). This value dictates the minimum length of a possible defect. Set a higher value to decrease the number of calipers when only coarse defect detection is needed. To detect smaller defects, set a lower value to increase the number of calipers. Example:
Smoothing Factor	Specifies how much influence uneven edges have on the best fit line for the trained bead path (1 - 10; default = 3). Use a higher value to make the best fit bead path less sensitive to variations such as spikes along the edges of the bead. Use a lower value when the bead edges are very smooth. Example:

Train Bead Path

Click this button to train the bead path.

During training, detailed analysis of the bead characteristics is calculated. These calculations are used to set initial values for an InspectBead function that references this TrainBead tool.

Note: If you retrain the TrainBead tool, any InspectBead tool that references the TrainBead tool is modified with updated bead characteristics. Any customized masks or defect parameters get reset.

Show Graphics

Specifies which TrainBead graphical overlays to display on top of the image.

Bead Path	Displays the best fit line along the selected bead path either in blue if a bead path is not trained or in green if a bead path is trained. Note: Once a bead path is found, bead path is always displayed while the TrainBead property sheet is open. Example:
Bead Edges	Displays the positions of the bead edges that have been detected along the bead path. If an edge is not found, yellow circles are displayed to indicate where the edge is expected to be found. Example:
Bead Edges (Average)	Displays the average positions of bead edges that have been detected along the bead path. Example:
Calipers	Displays the calipers along the bead path. The calipers for the selected bead path candidate is displayed in green. The calipers for the trained bead path are displayed in one of the following colors: Green: Both edges are found. Yellow: Miss an edge and fill edge is used. Black: Miss both edges and mask is applied. Example:
Subtracted Image	Displays the subtracted image created by subtracting an active image with a Background Image. Note: The tool generates the subtracted image after you clicked the Find Bead Paths button. Example:

TrainBead Outputs

Returns

A Bead data structure containing the information about detected beads in the image, or #ERR if any of the input parameters are invalid.

Results

When TrainBead is initially inserted into a cell, a results table is created in the spreadsheet. For example, this is the default TrainBead results table: