<?php
remove_filter( 'HEADER_IMAGE_WIDTH', 'twentyeleven_header_image_width' );
remove_filter( 'HEADER_IMAGE_HEIGHT', 'twentyeleven_header_image_height' );
define( 'HEADER_IMAGE_WIDTH', apply_filters( 'child_header_image_width', 1245 ) );
define( 'HEADER_IMAGE_HEIGHT', apply_filters( 'child_header_image_height', 200 ) );