<?php
function pd_fix_wp_upload_dir_ssl( $uploads ) {
	$orig_scheme = $scheme;
	if ( !in_array( $scheme, array( 'http', 'https' ) ) ) {
		if ( ( 'login_post' == $scheme || 'rpc' == $scheme ) && ( force_ssl_login() || force_ssl_admin() ) )
			$scheme = 'https';
		elseif ( ( 'login' == $scheme ) && force_ssl_admin() )
			$scheme = 'https';
		elseif ( ( 'admin' == $scheme ) && force_ssl_admin() )
			$scheme = 'https';
		else
			$scheme = ( is_ssl() ? 'https' : 'http' );
	}

	$uploads['url'] = str_replace( 'http://', "{$scheme}://", $uploads['url'] );
	$uploads['baseurl'] = str_replace( 'http://', "{$scheme}://", $uploads['baseurl'] );
	
	return $uploads;
}
add_filter('upload_dir', 'pd_fix_wp_upload_dir_ssl');