Now, I see. Well, you could this in one of two ways, either use DOM to get the nodeValue you need,
OoOr, use regex.
In your case I think you need to use regex, because you are sending the data back as a string, but I'm not sure about this.
For PHP RegEx functions you will find all you need to know here: http://se.php.net/manual/en/ref.pcre.php
And I think what you are looking for is this function: http://se.php.net/manual/en/function.preg-match.php
Now, I suck at PHP -- yeah, I know, I should have told you that in the beginning, but whatever -- so I can't help you with RegEx... Not that much anyway...
I'm not sure but these patterns could maybe match what you are looking for:
Backslash () escapes stuff, ex. \/ will be interpreted as /.
The i after / means that the search is case insensitive.
The characters that go from a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z are a set of glyphs that represent the English language.
$pattern_width = '/width="[0-9]"$/i';
$pattern_height = '/height="[0-9]"$/i';
// note: I do not know if you need to escape the equal thingy (=), I do not think so.
$pattern_src = '/(http:\/\/|http:\/\/www.)[a-z0-9]*"/i';
// I do not know what RegEx represents special characters such as underscore or dots so this expression would not match those. You could try to replace [a-z0-9] with . (a dot) it means it would match any character, however I think this would create a security issue if the user is allowed to enter any character into your form.
Anyhow, like I said, I do not know much about RegEx, check out the URI's I gave, and see if you will get any wiser.
I recommend that you mark this thread as resolved and ask a new question about how to RegEx your querry (or doing this with DOM) after you have searched the forum, because there have been many questions about this (RegEx, at least)... I think...
Good luck to you.