Centering dynamically loaded jpg's

Hi all,
I have some code that loads jpegs from a folder into a movie clip but as you all know the registration point is 0,0 or top left. All my images are different sizes and a combo of landscape and portrait and I’d like them to all load centrally but I can’t figure out how to do it.
I did try a work around where I converted them to png’s with transparency so that thhe image appeared central although flash won’t load the png’s.
I’ve included the code and would be very grateful for any help

<–
this.pathToPics = “…/Images/comm_lg/”;
// fill this array with your pics
this.pArray = [“image_01.jpg”, “image_02.jpg”, “image_03.jpg”, “image_04.jpg”, “image_05.jpg”, “image_06.jpg”, “image_07.jpg”, “image_08.jpg”, “image_09.jpg”, “image_10.jpg”, “image_11.jpg”, “image_12.jpg”, “image_13.jpg”, “image_14.jpg”, “image_15.jpg”, “image_16.jpg”, “image_17.jpg”, “image_18.jpg”, “image_19.jpg”, “image_20.jpg”, “image_21.jpg”, “image_22.jpg”, “image_23.jpg”, “image_24.jpg”, “image_25.jpg”, “image_26.jpg”, “image_27.jpg”, “image_28.jpg”];
this.fadeSpeed = 20;
this.pIndex = 0;
// MovieClip methods ----------------------------------
// d=direction; should 1 or -1 but can be any number
//loads an image automatically when you run animation
loadMovie(this.pathToPics+this.pArray[0], _root.photo);
MovieClip.prototype.changePhoto = function(d) {
// make sure pIndex falls within pArray.length
this.pIndex = (this.pIndex+d)%this.pArray.length;
if (this.pIndex<0) {
this.pIndex += this.pArray.length;
}
this.onEnterFrame = fadeOut;
};
MovieClip.prototype.fadeOut = function() {
if (this.photo._alpha>this.fadeSpeed) {
this.photo._alpha -= this.fadeSpeed;
} else {
this.loadPhoto();
}
};
MovieClip.prototype.loadPhoto = function() {
// specify the movieclip to load images into
var p = _root.photo;
//------------------------------------------
p._alpha = 0;
p.loadMovie(this.pathToPics+this.pArray[this.pIndex]);
this.onEnterFrame = loadMeter;
};
MovieClip.prototype.loadMeter = function() {
var i, l, t;
l = this.photo.getBytesLoaded();
t = this.photo.getBytesTotal();
if (t>0 && t == l) {
this.onEnterFrame = fadeIn;
} else {
trace(l/t);
}
};
MovieClip.prototype.fadeIn = function() {
if (this.photo._alpha<100-this.fadeSpeed) {
this.photo._alpha += this.fadeSpeed;
} else {
this.photo._alpha = 100;
this.onEnterFrame = null;
}
};
–>

Cheers
Hitby