Index: wp-includes/post-template.php
===================================================================
--- wp-includes/post-template.php	(revision 21260)
+++ wp-includes/post-template.php	(working copy)
@@ -1147,7 +1147,7 @@
 	if ( $permalink )
 		$url = get_attachment_link( $_post->ID );
 
-	$post_title = esc_attr( $_post->post_title );
+	$post_title = esc_attr( wptexturize( $_post->post_title ) );
 
 	if ( $text )
 		$link_text = $text;
Index: wp-includes/media.php
===================================================================
--- wp-includes/media.php	(revision 21260)
+++ wp-includes/media.php	(working copy)
@@ -228,7 +228,7 @@
 	$class = 'align' . esc_attr($align) .' size-' . esc_attr($size) . ' wp-image-' . $id;
 	$class = apply_filters('get_image_tag_class', $class, $id, $align, $size);
 
-	$html = '<img src="' . esc_attr($img_src) . '" alt="' . esc_attr($alt) . '" title="' . esc_attr($title).'" '.$hwstring.'class="'.$class.'" />';
+	$html = '<img src="' . esc_attr($img_src) . '" alt="' . esc_attr(  wptexturize( $alt ) ) . '" title="' . esc_attr(  wptexturize( $title ) ).'" '.$hwstring.'class="'.$class.'" />';
 
 	$html = apply_filters( 'get_image_tag', $html, $id, $alt, $title, $align, $size );
 
@@ -659,13 +659,13 @@
 		$default_attr = array(
 			'src'	=> $src,
 			'class'	=> "attachment-$size",
-			'alt'	=> trim(strip_tags( get_post_meta($attachment_id, '_wp_attachment_image_alt', true) )), // Use Alt field first
-			'title'	=> trim(strip_tags( $attachment->post_title )),
+			'alt'	=> trim( wptexturize( strip_tags( get_post_meta($attachment_id, '_wp_attachment_image_alt', true) ) ) ), // Use Alt field first
+			'title'	=> trim( wptexturize( strip_tags( $attachment->post_title ) ) ),
 		);
 		if ( empty($default_attr['alt']) )
-			$default_attr['alt'] = trim(strip_tags( $attachment->post_excerpt )); // If not, Use the Caption
+			$default_attr['alt'] = trim( wptexturize( strip_tags( $attachment->post_excerpt ) ) ); // If not, Use the Caption
 		if ( empty($default_attr['alt']) )
-			$default_attr['alt'] = trim(strip_tags( $attachment->post_title )); // Finally, use the title
+			$default_attr['alt'] = trim( wptexturize( strip_tags( $attachment->post_title ) ) ); // Finally, use the title
 
 		$attr = wp_parse_args($attr, $default_attr);
 		$attr = apply_filters( 'wp_get_attachment_image_attributes', $attr, $attachment );