imgNms = new Array('picsup',
                   'picsdown');

ovrImgs = new Array('../images/picture-box-up-o.gif',
                    '../images/picture-box-down-o.gif');

outImgs = new Array('../images/picture-box-up.gif',
                    '../images/picture-box-down.gif');

imgCnt = imgNms.length;
ovrPcs = new Array(imgCnt);
outPcs = new Array(imgCnt);

for (var j=0 ; j<imgCnt ; j++)
{
  ovrPcs[j] = new Image;
  ovrPcs[j].src = ovrImgs[j];
  outPcs[j] = new Image;
  outPcs[j].src = outImgs[j];
}

function subSwImg(subNum, subState)
{
  if (document.images){
    var subImgName = imgNms[subNum];
  
    if (subState == 'b')
    {
      document[subImgName].src = ovrPcs[subNum].src;
    }
    else if (subState == 'a')
    {
      document[subImgName].src = outPcs[subNum].src;
    }
  }
}

accelerating = false;
function decelerate()
{
  if (imagescroller.scrollAmount > 0)
  {
    imagescroller.scrollAmount -= 1;
  }
  
  if (imagescroller.scrollAmount > 0 && !accelerating)
  {
    setTimeout("decelerate()",100);
  }
}

function accelerate()
{
  if (imagescroller.scrollAmount < 10)
  {
    imagescroller.scrollAmount += 1;
  }
  
  if (imagescroller.scrollAmount < 10 && accelerating)
  {
    setTimeout("accelerate()",200);
    accelerating = true;
  }
}