Kategoriebasiertes Header Image

<?php
    // Check to see if the header image has been removed
    $header_image = get_header_image();
    if ( $header_image ) :
     // Compatibility with versions of WordPress prior to 3.4.
     if ( function_exists( 'get_custom_header' ) ) {
      /*
       * We need to figure out what the minimum width should be for our featured image.
       * This result would be the suggested width if the theme were to implement flexible widths.
       */
      $header_image_width = get_theme_support( 'custom-header', 'width' );
     } else {
      $header_image_width = HEADER_IMAGE_WIDTH;
     }
     ?>
   <a href="<?php echo esc_url( home_url( '/' ) ); ?>">
    <?php
     /*
      * The header image.
      * Check if this is a post or page, if it has a thumbnail, and if it's a big one
      */
     if ( is_singular() && has_post_thumbnail( $post->ID ) &&
       ( /* $src, $width, $height */ $image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), array( $header_image_width, $header_image_width ) ) ) &&
       $image[1] >= $header_image_width ) :
      // Houston, we have a new header image!
      echo get_the_post_thumbnail( $post->ID, 'post-thumbnail' );
     else :
      // Compatibility with versions of WordPress prior to 3.4.
      if ( function_exists( 'get_custom_header' ) ) {
       $header_image_width  = get_custom_header()->width;
       $header_image_height = get_custom_header()->height;
      } else {
       $header_image_width  = HEADER_IMAGE_WIDTH;
       $header_image_height = HEADER_IMAGE_HEIGHT;
      }
      ?>
     <img src="<?php header_image(); ?>" width="<?php echo $header_image_width; ?>" height="<?php echo $header_image_height; ?>" alt="" />
    <?php endif; // end check for featured image or standard header ?>
   </a>
   <?php endif; // end check for removed header image ?>