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Correcting for Uneven Machine Vision Lighting with a Software Tool

  
  
  
  
  

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

 light level tool resized 600

IMAGE WITH LIGHT LEVELING TOOL

 light level tool2 resized 600

light level3 resized 600

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.

Comments

What if the lighting conditions change slowly, say sunlight moving during the day, light sources getting dirty etc. Would it be possible to increase / decrease individual light sources based on feedback from your camera?
Posted @ Wednesday, February 09, 2011 2:12 AM by Michel Coene
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