var Images = new Array;

function higImg(self)
{
	im = replaceCharacters(self.src, '.png', '-high.png');
	img = inArray(Images, im);
	if (img == 'NaN')
	{
		img = new Image();
		img.src = im;
		Images = toArray(Images, im, img);
	}
	self.src = img.src;
}

function unhigImg(self)
{
	im = replaceCharacters(self.src, '-high.png', '.png');
	img = inArray(Images, im);
	if (img == 'NaN') 
	{
		img = new Image();
		img.src = im;
		Images = toArray(Images, im, img);
	}
	self.src = img.src;
}

function toArray(a, key, value)
{
	a.push(key, value);
	return a;
}

function inArray(a, key)
{
	for (i = 0; i<a.length; i+=2)
	{
		if (a[i] == key)
		{
			 return a[i+1];
		} 
	}
	return 'NaN';
}

function replaceCharacters(conversionString, inChar, outChar)
{
  var convertedString = conversionString.split(inChar);
  convertedString = convertedString.join(outChar);
  return convertedString;

}