Dust and Particle Detection

Dust and Particle Detection Overview

Particle detection tests are available that detect dust, dirt, and other foreign materials in an otherwise uniform image. User configurable size threshold settings are available, as well as configurable regions and total allowable particle settings. The particle detection algorithm usually ignores single defective or dead pixels, as they are not usually dust or particle related.

Background correction algorithms are employed to increase the sensitivity of the algorithm. Configurable algorithms settings allow further tuning of the algorithm for the desired sensitivity. A report of each found particle is returned that includes the total number of particles found and the X and Y coordinates and the particle area of each particle. This test is typically performed on 8-bit monochrome luminance plane image types.

Dust and Particle Detection Algorithm

The Dust and Particle Detection algorithm contains a background subtraction image-processing step that can be selected to help eliminate lens-shading effects. The correction algorithm uses an Nth order filter and has user configurable kernel size and percentile threshold algorithm inputs.

A user specified deviation from mean threshold is used to detect the darker particles in the image. Another user input controls the minimum size threshold for particles and can be used to eliminate isolated pixels defects from the final report.

The maximum number of allowable detected particles can also be configured for use in Pass/Fail testing.

Dust and Particle Detection Input Parameters

Name	Description
Input Image	An 8-bit monochrome luminance image is required for this test.
Particle Detection Method	Specifies Standard or Background Corrected method of particle detection.
Background Subtraction On/Off	Specifies if the background subtraction algorithm is enabled.
Background Subtraction Filter Nth Order Kernel Size	Specifies the X and Y grid size of the kernel used for the Nth order filter.
Background Subtraction Filter Nth Order Percentile Threshold	Specifies the percent threshold used to the order classification of the filter.
Particle Threshold	Specifies the pixel intensity deviation from background threshold for classifying detected particles.
Maximum Number of Particles	Specifies the maximum number of allowable particles.

Dust and Particle Detection Outputs

Name	Description
Detected Particles Table	A table report output contains statistics on every detected particle including particle area, width, height, center of massX and center of massY.
Detected Particle Image	An output binary image is available with a black background and with every detected particle shown in white. Text with the total particle count is also overlaid on the image.