Hello,In our test application, we are using a Basler A641f fw camera to capture images, and do pattern matches of, a phone LCD screen. We have come across a phone that, when grabbing images, there is a walking horizontal line in successive frames, that slowly moves up the screen. Think of when you see on TV, a camera is filming another screen in the scene. That is similar to what I am seeing. This has the potential to effect our pattern matches, because the location of the horizontal line may or may not be within our ROI when we do the pattern match. My theory is that it has something to do with the refresh rate of the LCD being close to the refresh rate of the camera ccd, both of which our out of my control. Does anyone know a way to compensate for this? Has anyone else run into this phenomenon when capturing display images?ThanksDavid Jenkinson

Machine Vision

weird rasterization effect when capturing LCD screen

David, this LCD's behaviour doesn't sound familiar to me. T McCarty correctly stated how LCDs work. I would trust your acquired images even if you cannot observe the "walking line" behaviour with your eyes.
Hopefully, an "LCD hero" will join this thread and let us know what this LCD is doing.
I am interested in any approach that improves/solves your issue.

Guenter

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Machine Vision

weird rasterization effect when capturing LCD screen

Re: weird rasterization effect when capturing LCD screen