hi , i was thinking about this, maybe you have the answer:

How can i make a program that selects random clusters of pixels from a image? what i mean is that the program selects a group of random pixels that are near one from each other

Are there any strategy for selecting random clusters of pixels from an image?

The only condition i waould like if that it never selects pixels from the borders , is it possible to do something like this?

any idea?

thanks


Seb.

Well you can use get() to get a pixel from the screen (though note that "pixels[y*width+x]" is supposed to be quicker), so that just leaves you with how you define the points you need.  If you want to take random points from a rectangular area you could set a random start point for this area (making sure it's away from the borders) and then get points at random from within the rectangle.

Code:

void setup(){
  size(400,300);

  // let's say the rectangle is 100 x100 - actually a square ;)
  int rectW = 100;
  int rectH = 100;
  // start point that offsets by a specified amount from the border
  int offset = 30;
  float startX = offset + random((width-rectW-offset*2));
  float startY = offset + random((height-rectH-offset*2));
  int numberOfPoints = (int) random(100,300);
  for(int i=0; i<numberOfPoints; i++){
    float pointX = random(rectW);
    float pointY = random(rectH);
    // here rather than drawing something you'd do a get() on the coordinates
    noStroke();
    fill(0);
    rect(startX+pointX,startY+pointY,1,1);
  }

} 

Now that's fairly crude and probably not what you want; but the principle seems sound.  A better approach would be to get points within the radius of a circle centred on the random location.  That shouldn't be too difficult: instead of randomising x and y you'd just get a random angle between 0 and 360 degrees and a random radius within the threshold and apply a little trigonometry.  And you'd obviously need to change the offset to take account that you'd be getting from the centre rather than a corner...