code: function(name, url, extent, size, options) {
          this.url = url;
          this.extent = extent;
          this.maxExtent = extent;
          this.size = size;
          OpenLayers.Layer.prototype.initialize.apply(this, [name, options]);
  
          this.aspectRatio = (this.extent.getHeight() / this.size.h) /
                             (this.extent.getWidth() / this.size.w);
      }
docs: Constructor: OpenLayers.Layer.Image
  Create a new image layer
  
  Parameters:
  name - {String} A name for the layer.
  url - {String} Relative or absolute path to the image
  extent - {<OpenLayers.Bounds>} The extent represented by the image
  size - {<OpenLayers.Size>} The size (in pixels) of the image
  options - {Object} Hashtable of extra options to tag onto the layer