I would like to create an RGB color picker based on the the XY color spectrum. I have some LEDS and would like to select the color using the spectrum rather the three faders. this would require controlling the 3 faders using only 2.

I created a patch but could only get this far.

any help would be greatly appreciated. Thank you in advance.

here is a link of what i'm talking about.

http://www.google.com/imgres?imgurl=http://blommit.com/wp-content/uploads/2008/12/spectrum.jpg&imgrefurl=http://blommit.com/2008/12/27/the-ones-we-cant-see/&h=400&w=600&sz=21&tbnid=HguLqKMqh9ywVM:&tbnh=90&tbnw=135&prev=/images%3Fq%3Dcolor%2Bspectrum&zoom=1&q=color+spectrum&usg=__iomySBgMqPG4XqpLHr0-rpOReG8=&sa=X&ei=PP1ZTYqNNcTYgAe4zLCdDQ&ved=0CCYQ9QEwAA

http://www.pdpatchrepo.info/hurleur/X_Y_spectrum_picker.pd

Hello djbigh:
I think that you will have to deal with colour spaces. The image that is shown in the link you posted is a non linear representation of the RGB colour space. It seems that in the picture the vertical axis is value or saturation and horizontal axis is hue in an HSV colour space. Please note that the scale of gray is shown on top of the picture. For a mathematical conversion this could be a drawback.
If you need colours and not grayscales such representation could be useful for you. I searched in the web for some algorithm that could give us the pixel colour in RGB as a result of X and Y coordinates. I found these following link useful:

http://en.wikipedia.org/wiki/HSL_and_HSV
http://www.easyrgb.com/index.php?X=MATH&H=21#text21

Good luck!

Sumidero

PD: I'm sorry it is quite late and my neurons do not respond at full capacity so as to give a proper answer or patch.

Hi,

1- For conversion between colorspaces (hsv to rgb or vice-versa) you can use [hsv2rgb] and [rgb2hsv], which is I guess what Sumidero's second link suggests.

2- I'm looking fo something similar, be it that I'm trying to find a way of reading out specific points in rendered gradients. I'm using [colorsquare] and basically want to read out a number of points spread in this rectangle, e.g. 6 equally spaced points where I'd pick the color, and later send it to a series of LEDs. Yes, you could say that is basically the same as reducing the resolution of the gradient (a 2D line is fine with me) to 6 steps. But I'll be mixing colors in realtime creating various complex meshes. I guess I should make some way of reading out particular points in the array of that updated color mesh... Anyone who can help me with that?

Thanks, siziw.

Just in case you didn't know, there is something like [colorpanel]..