Creo que esto te servira:
The getimagesize() function will determine the size of any GIF, JPG, PNG, SWF, PSD, TIFF or BMP image file and return the dimensions along with the file type and a height/width text string to be used inside a normal HTML IMG tag.
Returns an array with 4 elements. Index 0 contains the width of the image in pixels. Index 1 contains the height. Index 2 a flag indicating the type of the image. 1 = GIF, 2 = JPG, 3 = PNG, 4 = SWF, 5 = PSD, 6 = BMP, 7 = TIFF(intel byte order), 8 = TIFF(motorola byte order, 9 = JPC, 10 = JP2, 11 = JPX. Index 3 is a text string with the correct height="yyy" width="xxx" string that can be used directly in an IMG tag. Example 1. getimagesize (file)
<?php
$size = getimagesize ("img/flag.jpg");
echo "<img src=\"img/flag.jpg\" {$size[3]}>";
?>
Example 2. getimagesize (URL)
<?php $size = getimagesize ("http://www.example.com/gifs/logo.gif"); ?>
