Introduction

With the help of the background differencing operator, we can now identify objects from the background much more clearly, especially transparent objects, for which we were previously unable to detect the contours properly.

Requirements

To use the Background Differencing Operator, you must have an active ContourTrace Premium subscription, which provides access to the Image Stitching with Position Markers (ISPM) module.

We need the Image Stitching with Position Markers (ISPM) module to generate and create, and save the background images, which the operator will later use.

The stitched image background should also have the same light intensity as the background image to get the desired results.

Choosing the Right Conditions to generate the background image

This process should be performed in a closed environment; having different light sources might affect the process of differencing in the final result. The best results can be obtained by using our Automatic Area Scan portal when creating the background image.

If a light reflection reduction foil is used with the Automatic area scan portal, use the highest light intensity on the light plate, which helps the algorithm to identify the objects much more clearly.

General Guidelines

• Ensure all the objects are removed from the position mark template.
• Ensure the correct template is used. Go through How to use Position Marker Templates, to understand how to use them properly.

Create a Background Image

1. Manually creating a background image.
   • If you are using the Area Scan Portal Manual or the camera option.
   • Click on “Generate Image” to start the image Stitching process.
   • Move the camera smoothly and slowly over the entire template till all the background of the template is stitched.
2. Creating the default background image using the Automatic Area Scan Portal option.
   • Click on “Activate Background Differencing”
   • Click on the button “Create” under “Activate Background Differencing”

Save the background image

<image of ISPM, highlight the buttons used to save the background image>

1. Manually saving a background image
   • Save the background image with
     • Enabling “heal the unscanned and remove area”
     • Enabling “remove position markers”
     • Enabling “set unscanned areas to white”
2. Saving the default background image using the Automatic Area Scan Portal Saving option.
   • After the image stitching process is complete.
   • Click on the button “Save” under “Activate Background Differencing”.
   • To see the default saved background image, click on the “open” under “Activate Background Differencing” (Optional).

💡 Tip

Always ensure both the images are create in a close environment. lighting changes and shadows effects the differencing process

How to use the background image on the “Background Differencing” operator

1. Go to the “Background Differencing” operator tab in the main application.
2. Check the On/Off checkbox to activate the operator.
3. If the background image is saved manually
   • Click on the “Add” button to browse and select the correct background image.
   • Use the “Blur Threshold” and “Difference” till only the objects are visible in the view.
4. If the background image is saved using the Automatic Area Scan Portal Saving option
   • Click on the “Use Default” button on the operator to load the default image saved in the “ISPM” module
   • Use the “Blur Threshold” and “Difference” till only the objects are visible in the view.

Bad Results for Background Image