Can I Subtract a background using IMAQ

[Terry_S]

I am evaluating vision software as a possible solution to building an online particle size analyzer. One of the issues that I have to deal with is uneven lighting. With other software I am able to correct this by subtracting a background image from the captured image. Is it possible to get this function using the vision.

[BruceAmmons]

You can subtract one image from another using IMAQ. This is one of many tools available.

It is also possible to estimate the light level by using a large averaging filter, then subtract the resulting image from the original image.

Bruce

[Terry_S]

I can not seem to figure out how to do the subtaction. Could you explain which tools in Vision Builder I need to use.

[KenSun]

Terry,

In Vision Builder, you can go to Grayscale->Operators and select subtract.

You can either subtract the image by a constant value, or if you have multiple images opened, you can perform a subtraction on two images.

Hope this helps.

Ken Sun
Applications Engineering
National Instruments