modal auto height and width

[ctrlSoft]

i want to add images dinamicaly in modal.
 

> $(".photothumb").live("click", function(){ 
>
>             $('#myModal').modal() 
>
>             url = $(this).attr('url')                                     
>>                   
>
>             $(".modal-body").html("<img src='"+url+"' alt=''/>")   
>
>
<div id="myModal" class="modal fade" style="display: none; ">
    <div class="modal-header">
      <a class="close" data-dismiss="modal">×</a>
      <h4>Photo Title</h4>
    </div>
    <div class="modal-body">
    </div>
    <div class="modal-footer">
        <button class="btn" id="deletePhoto"><i 
class="icon-trash"></i>Delete</button>
    </div>
</div> 

everythig works fine, but i have some images with different size (600x300) 
or (250x500)....and there is appearing scroll, how can i set "#myModal" 
with: auto width and height