yes, you can know the dimensions of the image, try<form name="form1">
<input type="file" name="file1" onpropertychange="document.all('imgtest').src=this.value;"><input type="text" name="imgsize" readonly>
</form>
<img id="imgtest" 
onload="document.form1.imgsize.value=this.width+'x'+this.height;" 
onabort="document.form1.imgsize.value='0x0';" 
onerror="document.form1.imgsize.value='0x0';">