Description:

The Blob1 tool finds one or more (currently up to 15) blobs, in the configured region of interest (ROI).

A blob is a set of pixels with similar properties, which are connected to each other. The 'property' used for blob detection by the Blob1 tool is the pixel intensity value, as configured in the Blob1 tool. The boundary of a blob is called as contour. Each blob may have 0 or more holes inside it.


Blob area = A
Hole area 1 = H1
Hole area 2 = H2
Contour area = A+H1+H2

A more powerful Blob4 tool is available in the Advanced tools category.

Please refer to the Locate detail with Blob topic which demonstrates the configuration for the blob detection.

User Interface:

(A) Tool Configuration dialog box - Setup Tab



1. The ‘Reference’ drop down can be used to select the input 2D reference. The input 2D reference provides the origin (0,0) and rotation of the X and Y-axis. It is strongly recommended to click on the 'Apply' button available on the main tool configuration window, to apply the newly selected input reference. This reference is then used while configuring all other tool parameters.
2. The ‘Search area’ group can be used for defining the region of interest (ROI) for the ‘Intensity’ tool processing. The ‘Search area’ is expected to be a rectangle.
3. ‘Center-X’ is used to provide the X co-ordinate of the center of the search area rectangle. The co-ordinates are relative to the input 2D reference.
4. ‘Center-Y’ is used to provide the Y co-ordinate of the center of the search area rectangle.
5. ‘Size-X’ is used to provide the size of the search area in the direction of the X-axis as indicated by the input 2D reference.
6. ‘Size-Y’ is used to provide the size of the search area in the direction of the Y-axis as indicated by the input 2D reference.
7. It is possible to type in fixed values for the ‘Search area’ properties – ‘Center-X’, ‘Center-Y, ‘Size-X’ and ‘Size-Y’. Also it is possible, to specify dynamic values for each one of these properties, by assigning them to any of the properties exposed from other tools defined in the Scorpion profile. The ‘…’ button available next to each of the ‘Search area’ properties user elements can be clicked to select a tool and its parameter to be assigned.



8. The ‘Copy’ button under the ‘Search area’ can be used to copy user defined region from the clipboard to the ‘Search area’ properties.



It is expected that a rectangle is defined on the image, by pressing the CTRL keyboard key and simultaneously using mouse left button click to define vertexes of the target rectangle. When ‘Copy’ button is clicked, the search area parameters are copied from the polygon on the image and are updated in the ‘Search area’ properties on the configuration dialog box. If use has not defined a perfect rectangle, or has defined any other polygon, a bounding rectangle is calculated and is used for updating the ‘Search area’ properties on the configuration dialog box.
If only single point is selected on the image, and ‘Copy’ button is clicked, only the center of the ‘Search area’ is updated. Which means that the values for ‘Center-X’ and ‘Center-Y’ are updated whereas the values for ‘Size-X’ and ‘Size-Y’ are unchanged.
If only 2 or 3 points are selected on the image, and the ‘Copy’ button is clicked, it is ignored and has no effect.
9. The ‘Paste’ button under the ‘Search area’ can be used to paste the ‘Search area’ properties to the clipboard. This is useful in viewing the exact location of the search area on the inspection image and fine-tuning, if required.
10. The 'Sobel filter' check-box under the ‘Emphasizing gradients’ group, can be enabled to apply sobel filter on the input image before processing for the blob detection.
11. The '[e=erode, d=dilate]' textbox under the 'Morphology' group can be used to apply erosion and dilation operations on the located blob areas. The text input expected in this text box is 'e<n>d<m>' where <n> and <m> indicate numbers. E. g. e2d2e3 applies 2 pixels erosion, then 2 pixels dilation and finally 3 pixels erosion. This is used typically for smoothening of the blob boundaries. It is possible to type in fixed values for the ‘[e=erode, d=dilate]’ parameter, it is also possible to specify dynamic value, by assigning them to any of the properties exposed from other tools defined in the Scorpion profile. The ‘…’ button available next to the ‘[e=erode, d=dilate]’ can be clicked to select a tool and its parameter to be assigned.
12. The ‘Area search’ group is used for specifying the blob search parameters.
13. The 'Minimum threshold' textbox is used to specify the minimum threshold for the intensity value.
14. The 'Maximum threshold' textbox is used to specify the maximum threshold for the intensity value. If pixel intensity value is greater than the minimum threshold and is lesser than the maximum threshold, it is considered as a blob pixel.
15. The 'Max is inclusive' check-box can be checked to include the maximum threshold in the detection range. If this is checked, a pixel is considered as blob pixel, if the pixel intensity value is greater than the minimum threshold and is lesser than or equal to the maximum threshold.
16. The 'Smooth factor' textbox can be used to specify the blob contour smoothening factor.
17. It is possible to type in fixed values for the ‘Area search’ properties – ‘Minimum threshold’, ‘Maximum threshold' and ‘Smooth factor’. Also it is possible, to specify dynamic values for each one of these properties, by assigning them to any of the properties exposed from other tools defined in the Scorpion profile. The ‘…’ button available next to each of the ‘Area search’ properties user elements can be clicked to select a tool and its parameter to be assigned.
18. The 'Result validation' group is used for configuring validation settings for the detected blobs. The detected blobs which do not follow these validations are removed from the results. The result validation settings are very useful for removing obvious false detections and getting overall good accuracy from the blob detection. The Blob4 tool has more advanced result validation, for further pruning of the results for getting further better accuracy.
19. The 'Smallest area' check-box can be checked to enable the minimum blob area validation. If blob area of any of the detected blobs is lesser than the specified smallest area threshold, it is removed from the final list of detected blobs.
20. The 'Largest area' check-box can be checked to enable the maximum blob area validation. If blob area of any of the detected blobs is greater than the specified largest area threshold, it is removed from the final list of detected blobs.
21. It is possible to type in fixed values for the ‘Result validation’ properties – ‘Smallest area’ and ‘Largest area’. Also it is possible, to specify dynamic values for each one of these properties, by assigning them to any of the properties exposed from other tools defined in the Scorpion profile. The ‘…’ button available next to each of the ‘Result validation’ properties user elements can be clicked to select a tool and its parameter to be assigned.
22. The 'Tool fails if nothing is found' check-box under the 'Status' group, can be checked to set the tool processing result to 'fail', if no blob is detected in the blob detection process. By default, the Blob1 tool processing result is set to 'pass', whenever the tool processing is completed successfully, irrespective of the number of blobs detected.