custom header on 'page for posts' page

                <?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( get_option( 'page_for_posts' ) ) $the_id = get_option( 'page_for_posts' );
if( is_singular() ) $the_id = $post->ID;
                if ( (is_singular() || get_option( 'page_for_posts' )) &&
                            has_post_thumbnail( $the_id ) &&
                            ( /* $src, $width, $height */ $image = wp_get_attachment_image_src( get_post_thumbnail_id( $the_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( $the_id, 'post-thumbnail' );
                    else : ?>
                    <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 ?>