[Fixed-Changed to JqZoom]Thickbox jpg set to 600x600, but image is scaled down to almost 50% smaller.

[dixie]

I have my product preference set to 600px x 600px for the thickbox, but when I click on the image to go to the thickbox, the image displayed is scaled down. I need to display an image in thickbox to be (at least) over 300px x 300px, which is the size of my product image. Also, there is a lot of white space around the image when in the thickbox. I need the thickbox to show a bigger image. I sell fabric and patterns on my website, so I need good close-up pictures. I am using Prestashop 1.3.1

Also, I don't know coding, but I can copy/paste. Any help would be appreciated. Thank you!

Following is element code:
imgPreloader=new Image();imgPreloader.onload=function(){imgPreloader.onload=null;var pagesize=tb_getPageSize();var x=pagesize[0]-150;var y=pagesize[1]-150;var imageWidth=imgPreloader.width;var imageHeight=imgPreloader.height;if(imageWidth>x){imageHeight=imageHeight*(x/imageWidth);imageWidth=x;if(imageHeight>y){imageWidth=imageWidth*(y/imageHeight);imageHeight=y;[spam-filter]else if(imageHeight>y){imageWidth=imageWidth*(y/imageHeight);imageHeight=y;if(imageWidth>x){imageHeight=imageHeight*(x/imageWidth);imageWidth=x;[spam-filter]

Following is more code:
* {
margin:0;
padding:0;
}
#TB_window {
color:#333333;
font:12px Arial,Helvetica,sans-serif;
}
#TB_secondLine {
color:#666666;
font:10px Arial,Helvetica,sans-serif;
}
#TB_window h2 {
display:block;
padding-bottom:25px;
text-align:center;
}
#TB_overlay {
height:100%;
left:0;
position:fixed;
top:0;
width:100%;
z-index:100;
}
.TB_overlayMacFFBGHack {
background:url("../img/macFFBgHack.png") repeat scroll 0 0 transparent;
}
.TB_overlayBG {
background-color:#000000;
opacity:0.75;
}
* html #TB_overlay {
position:absolute;
}
#TB_window {
background:none repeat scroll 0 0 #FFFFFF;
border:4px solid #525252;
color:#000000;
display:none;
left:50%;
position:fixed;
text-align:left;
top:50%;
z-index:102;
}
* html #TB_window {
position:absolute;
}
#TB_window img#TB_Image {
border-color:#666666 #CCCCCC #CCCCCC #666666;
border-right:1px solid #CCCCCC;
border-style:solid;
border-width:1px;
display:block;
margin:15px 0 0 15px;
}
#TB_caption {
float:left;
height:25px;
padding:7px 30px 10px 25px;
}
#TB_closeWindow {
float:right;
height:25px;
padding:11px 25px 10px 0;
}
#TB_closeAjaxWindow {
float:right;
margin-bottom:1px;
padding:7px 10px 5px 0;
text-align:right;
}
#TB_ajaxWindowTitle {
float:left;
margin-bottom:1px;
padding:7px 0 5px 10px;
}
#TB_title {
background-color:#E8E8E8;
height:27px;
}
#TB_ajaxContent {
clear:both;
line-height:1.4em;
overflow:auto;
padding:2px 15px 15px;
text-align:left;
}
#TB_ajaxContent.TB_modal {
padding:15px;
}
#TB_ajaxContent p {
padding:5px 0;
}
#TB_load {
display:none;
height:13px;
left:50%;
margin:-6px 0 0 -104px;
position:fixed;
top:50%;
width:208px;
z-index:103;
}
* html #TB_load {
position:absolute;
}
#TB_HideSelect {
background-color:#FFFFFF;
border:medium none;
height:100%;
left:0;
opacity:0;
position:fixed;
top:0;
width:100%;
z-index:99;
}
* html #TB_HideSelect {
position:absolute;
}
#TB_iframeContent {
border:medium none;
clear:both;
margin-bottom:-1px;
margin-top:1px;
}
* + html #TB_window {
position:absolute;