Can't get my header to resize

Hi,

I have looked through the posts for a few hours and nothing that I tried worked.

What I have so far is that in the admin panel it shows the correct size but on the front end it’s squishing it to the orinal size of 940 by 198.

I changed this code to the correct size

define( 'HEADER_IMAGE_WIDTH', apply_filters( 'twentyten_header_image_width', 973 ) );
	define( 'HEADER_IMAGE_HEIGHT', apply_filters( 'twentyten_header_image_height', 297 ) );

I even tried this but I don’t know if I was putting it in the right place

add_filter('twentyten_header_image_height','my_header_height');
add_filter('twentyten_header_image_width','my_header_width');
function my_header_height($size){
   return 154;
}
function my_header_width($size){
   return 780;
}

I have also tried looking for it the style.css but found nothing useful.

If any one could point me in the right direction it would be a great help.