var yuipath = 'clientscript/yui';
var yuicombopath = '';
var remoteyui = false;
else // Load Rest of YUI remotely (where possible)
var yuipath = 'http://yui.yahooapis.com/2.9.0/build';
var yuicombopath = 'http://yui.yahooapis.com/combo';
var remoteyui = true;
Is there some reason you can't open it with microsoft photo editor (for one), and just resize the image? (Image, resize, use pixels as the unit?). If you're concerned about the original, of course, save it under a different name.
If that's all beside the point, obvious, or just not working, sorry. Not sure I have enough info to be exact enough.
A JPEG is a .jpg, unless I'm missing something mysterious..