This is excellent php function which can be used to get Width,Height,Type of a Image using PHP. for more information read PHP.net

list($width, $height, $type, $attr) = getimagesize("image_name.jpg");

echo "Image Properties";
echo "Width " .$width;
echo "<br/>";
echo "Height " .$height;
echo "<br/>";
echo "Type " .$type;
echo "<br/>";
echo "Attribute " .$attr;
Type of the image
1 = GIF5 = PSD9 = JPC13 = SWC
2 = JPG6 = BMP10 = JP214 = IFF
3 = PNG7 = TIFF(intel byte order)11 = JPX15 = WBMP
4 = SWF8 = TIFF(motorola byte order)12 = JB216 = XBM