RegExp.replace Not Working

[SamirDarji]

I'm using the following function to modify tags used for mouseover text:

function delHoverX()
{
  re = /(\bdsc00001\b)/i;

  imgTags = document.getElementsByTagName("img");
  for (i=0; i<imgTags.length; i++)
  {
    if (re.test(imgTags[i].title))
    {
      origTitle = imgTags[i].title;
      origAlt = imgTags[i].alt;
      imgTags[i].title.replace(re, "$1");
      imgTags[i].alt.replace(re, "$1");
      if (origTitle == imgTags[i].title && origAlt == imgTags[i].alt)
        {
        imgTags[i].title = "same";
        imgTags[i].alt = "same";
        }
    }
    else
    {
      imgTags[i].title = "";
      imgTags[i].alt = "";
    }
  }
}

It is being used on the following web page: http://huntsvillecarscene.smugmug.com/gallery/1144571

For some reason, the regexp.replace is not working. There is a test clause in there to help me diagnose some of what's going on.

I'm not a Javascript programmer. I only have a limited background in C. I've been working on this for 2 days and am frustrated out of my mind.

Any assistance appreciated.