code: public void setValue(final int channel, final int x, final int y, final double value){
  		this.data[channel][y*this.width + x] = value;
  	}
docs: Sets value at the specified position for the specified channel.
  No bounds checks will be performed, positions outside of this
  images dimension can either result in a value for a different position
  or an ArrayIndexOutOfBoundsException.
  
  @param channel the set value corresponds to
  @param x coordinate
  @param y coordinate
  @param value to be set at specified position. e.g. 0xff0000ff for blue color
  @throws ArrayIndexOutOfBoundsException if resulting index from x and y
  is not within the data arrays bounds
  or if the specified channel is not in [0,3]
  or is 3 but the image has no alpha (check using {@link #hasAlpha()}).
  @see #getValue(int channel, int x, int y)