Reading a bar-graph

[RichiP]

I need some help. I am pretty new to iMAQ Vision.
I am trying to read a bar-graph(like a VU meter with 10 leds). More current --> more led's light up. One problem may be the light (daylight or lamps). How can I solve this.
Regards
Richard

[BruceAmmons]

If the bar indicator is in a fixed position in the field of view, you can set up 10 ROIs, one for each bar of the indicator. For each one, I would include an area on either side that will stay dark when the LED is lit. You need to process each ROI to see if it is on. You might want to look at the profile across the ROI. For a lit LED, it will be dark on either end and bright in the middle. This should work even in bad lighting, unless the lighting is completely unworkable. In this case, you would need to put a shroud around the area to block the light. Another possibility is to record the image when the LED is off, and compare it to the reference to see if it is on.

If you don't have a fixed field of view, you will need to locate some reference points t
o figure out where the LEDs are.

Bruce