code: package org.sunflow.core;
  
  /**
   * Represents a multi-pixel image filter kernel.
   */
  public interface Filter {
      /**
       * Width in pixels of the filter extents. The filter will be applied to the
       * range of pixels within a box of <code>+/- getSize() / 2</code> around
       * the center of the pixel.
       * 
       * @return width in pixels
       */
      public float getSize();
  
      /**
       * Get value of the filter at offset (x, y). The filter should never be
       * called with values beyond its extents but should return 0 in those cases
       * anyway.
       * 
       * @param x x offset in pixels
       * @param y y offset in pixels
       * @return value of the filter at the specified location
       */
      public float get(float x, float y);
  }