Processing 1.0 - Processing Discourse - N00B - Reading H,S,B from pixel on mouse click.

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Index › Programming Questions & Help › Syntax Questions › N00B - Reading H,S,B from pixel on mouse click.

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N00B - Reading H,S,B from pixel on mouse click. (Read 578 times)

Kanemojo

N00B - Reading H,S,B from pixel on mouse click.
Nov 22^nd, 2006, 9:29pm

I'm using processing as a nice way to create "Photoshop-like" filters for post processing digital images.

I can read the photograph and set it as the background. Easy enough. I also have used vectors, particles, and a particle system as classes to generate crude particle motion (easy enough from examples).

But now I'd like to have the particles interact with the image and I'm stuck.

I have a particle system with the variables:
X position,
Y position,
H,
S,
B,
Transparency.

--------------------------------------------------
ps.addParticle(mouseX,mouseY,random(1,255),random(1,255),random(1,255),50);
--------------------------------------------------

Instead of random numbers I'd like to feed in the H,S,B values of the pixel of an image from the mouse click - basically from the X or Y position read in the existing H,S,B.

I'd like to play with taking a pixel of a photograph and having it move and mix with the other pixels.

Sort of like the smoke animations on this site but with the smoke as an actual pixel that "burns" through a saturation loss and brightness loss as it moves, and does not just overlay or mix using brightness but actually mixes with the existing pixel.

Any ideas?

I've tried to combine pixels[] with hue(), etc. without luck.

matthew.thompson

Re: N00B - Reading H,S,B from pixel on mouse click
Reply #1 - Nov 23^rd, 2006, 9:33am

So here's how I would go about loading in the color of the pixel under the mouse:

Code:


color c = get(mouseX, mouseY);

Or, if you want, you can replace mouseX or mouseY with whatever coordinate defining variable or function you prefer. Just as a way to typecheck something like that, though, I would pass those values mod (%) the width and height, respectively so that you aren't pulling pixels outside the canvas.

From there, you can pull the H S or B value using any of the Processing methods for color. I hope this helps!

Kanemojo YaBB Newbies Offline Posts: 6	Re: N00B - Reading H,S,B from pixel on mouse click Reply #2 - Nov 23^rd, 2006, 4:57pm Thanks Matt... I have the H,S,B as a single array as type color and the postition as a vector type, so actually grabbing the color this way is an excellent method. Using modulo on a percent... very creative. I never would have thought of that and I'm going to remember that neat trick.

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