Red LEDs?

[Jim Young]

I'm redesigning my LitePlacer setup and was wondering if there is any advantage to using red LEDs with the camera? I notice that some machines user them.

[Litterio Andrea Guainella]

Hi Jim,

if I remember correctly there is a post by Mark that gives his point of view on this.

And I seem to recall that with the red leds you lose a lot of the useful information that the more recent openpnp features use for fine tuning.

I hope I'm not wrong

LAG

[bert shivaan]

I think the consensus has been there is no real advantage for us. Maybe even a disadvantage.

On Fri, Nov 18, 2022 at 12:48 PM Jim Young <infinite...@gmail.com> wrote:

I'm redesigning my LitePlacer setup and was wondering if there is any advantage to using red LEDs with the camera? I notice that some machines user them.

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[Mark]

Hi

Yes, LAG summed this up nicely. We can use the color to do "green-screening", a bit like in Hollywood.

For the up-looking camera it can be nicely used with the green Juki nozzles and/or with a green shade that you can mount behind the nozzle. OpenPnP has background calibration to find the "knock-out" color (green is just the most often used color, but it can be any vivid/fully saturated color).

https://github.com/openpnp/openpnp/wiki/Nozzle-Tip-Background-Calibration

Be sure to also read about White Balance:

https://github.com/openpnp/openpnp/wiki/Camera-White-Balance

For the down-looking camera it is routinely used in the BlindsFeeder and can be used in the ReferencePushPullFeeder. I would also say it is mandatory for the AdvancedLoosePartFeeder.

https://github.com/openpnp/openpnp/wiki/BlindsFeeder

https://github.com/openpnp/openpnp/wiki/ReferencePushPullFeeder

https://github.com/openpnp/openpnp/wiki/AdvancedLoosePartFeeder

I recently posted an optimized "green screen" pipeline:

https://groups.google.com/g/openpnp/c/_wR7SlSjuvc/m/m6E23zefBQAJ

The only reason to still use red LEDs would be if you have a monochrome camera that you bought because it is truly much faster/has higher frames per second. AFAIK, these cameras have become rare at least in the DIY/consumer segment, i.e. the color cameras are now equally fast and still affordable. Those high end monochrome cameras that still have an edge, are not available with the USB/Webcam interface that OpenPnP supports, because it would make no sense performance-wise. The USB stack is too slow, too laggy, and OpenPnP could also likely not reasonably keep up with that frame rate (plus your machine would have to be super fast for this to make sense).

_Mark

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[Jim Young]

Thanks, Mark. Great summation.