Illumination Compensation


 

Correcting for Uneven Machine Vision Lighting with a Software Tool

By Brad Quist on Tue, Feb 08, 2011

Lighting a part to achieve very even lighting across the entire part can be a challenge for certain machine vision applications. In some cases, the only way to get a really good image is to use the Light Leveling Tool.

 

Below is an image of a plastic bottle with very slight uneven lighting across the image. The unevenness of the lighting makes it difficult to detect the actual defect because the grayscale value of the defect is the same as the other areas of the image.

 IMAGE WITHOUT LIGHT LEVELING TOOL


IMAGE WITH LIGHT LEVELING TOOL


 

The Light Leveling tool corrects for uneven lighting in an image. Within the Light Sensor Shape List area,the column or row with the highest average grey level is found (based on  the Direction To Level input). A scale factor is calculated for all the other columns or rows which brightens them so they have the same average grey level as the brightest column or row. Each column or row’s scale factor is then applied to all the pixels in that column or row within the entire Region To Copy.


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