Thursday, August 26, 2010

Why are machine vision people color-shy?

To those who know little to nothing about machine vision – like the average Operations V.P. - it seems obvious that vision systems should use color. After all, we see in color, the products we make are colored, so why not?

Well Ben Dawson of Dalsa does a good job of summarizing some of the challenges in “Color Machine Vision – Untouched by Human Eyes,” published in “rtcmagazine” back in January 2010. I’m not going to plagiarize Ben’s good work by telling you all the secrets here; you’ll have to click the link to learn the details. But as you read you’ll also learn about a family of Dalsa-based systems for inspecting baked products – muffins and the like.

These are built by Montrose Technologies Inc. out of Ottawa in Canada, and it seems they’ve found themselves a great niche for replicating inspection systems. I see no reason why their 3D, color inspection machines should be restricted to bakeries though, so if you need fast inspection of product placed randomly across a conveyor it might be worth firing off an email to these boys.

1 comment:

John Salls said...

I believe the reason most of us steer away from Color for our vision systems is that unless it is needed, it adds unnecessary cost and complexity to a system. Bakery goods are a perfect example where color becomes important. You want items baked to the perfect appearance, you want a certain number of fillings (blueberries, chocolate chips, etc.) to be visible. Because it affects the perceived quality of the product, color in that case is important. However, if you can accomplish the same task without color, the system will be cheaper. You can use Bandpass filters to control ambient light contamination and avoid building enclosures. You don't need to worry about the color of lights changing over time. You don't need to white balance the camera periodically.

Of the 300+ cameras I have worked on in the last 7 years, about a dozen required using a color camera. The remainder were monochrome cameras. I wouldn't say most vision people are color shy, we are just like everybody else and do things the cheapest, easiest way we can figure out how to do.