<< return to Pixycam.com

Questions about signature / color capture

Pixy Software
#1

I trying to use the Pixy to determine position of a robot. There will be color sign posts that are read.

I have tried using different colored paper or reflective tape. Even with a light source behind the camera I do not get the accuracy I would like. I have decided to use square LEDs and so far they are picking up far more accurately.

I have some questions:

Is the signature only about color saturation or is about color and shape?

Is there a specific Red / Green / etc color that the Pixy wants for each of the signatures or will it accept any “red” and then use that?

Is there a way in PixyMon to determine the “strength” of the color? This would help immensely when trying to tune the RGB LED to the correct color. If not, is there another way to do this?

What do Hue and Saturation do in settings? What are the acceptable values?

Thanks,
Peter

#2

Hi Peter,

The signature only takes in to account the color, not shape.

I’m not sure I understand your question. The signatures are based on what you used to teach Pixy, so the “red” it accepts is whatever shade of red the object is.

When you say ‘strength’, do you mean how well the color will work? Keep in mind that the algorithm used for generating the color LUT is hue-based. So a high-hue color works best.

Please see “this page”:http://cmucam.org/projects/cmucam5/wiki/Some_Tips_on_Generating_Color_Signatures for an explanation of the hue and saturation in settings.

Scott

#3

What are the ranges for Hue spread?

#4

Hi Peter,

As for the hue spread ranges, that will take a bit of explaining. As stated on the page I posted above, the hue spread value determines how inclusive/exclusive the color algorithm is to a an object’s range of hues. Basically, it is just a multiplier. You can think of the color algorithm as fitting a bounding box over the range of hues in the object, with the ‘hue spread’ being a multiplier on that bounding box that either expands (to be more inclusive) it or shrinks it (to be more exclusive). Therefore, there isn’t a strict range for this input. To get a better idea as to what values work, you may just need to play around with it to get an intuition for its affect on the color algorithm.

We’ll try to come up with a more formal definition (or just a better explanation) for this and post it on the wiki.

Hope this helps.

Scott