Wordpress image alt tag fixed based on image file name / title

wordpress-alt-tag-programmatically.php

<?php
/********************************************************
**  IMAGE ALT, GLOBAL FIX
**  run trough all existing images, grab the image title 
**  which is built using the filename automaticlly and 
**  asign it to the alt - at-least it wont be empty!
********************************************************/
add_action('after_setup_theme', 'image_alt_fix');
function image_alt_fix() {
	$args = array(
		'post_type' => 'attachment',
		'post_mime_type' => 'image/jpeg,image/gif,image/jpg,image/png',  
		'post_status' => 'all',  
		'posts_per_page' => -1, 
	);
	$imgs = new WP_Query( $args );


	if( $imgs->have_posts() ) {
		while( $imgs->have_posts() ) {
			$imgs->the_post();

			$tid 	= get_the_ID();
			$ttitle = get_the_title();
			$alt 	= get_post_meta($tid, '_wp_attachment_image_alt', true);


			if( empty($alt) ) {
				// testing: 
				// echo 'MISSED ALT TAG:'.get_the_title($tid).'<br>';
				update_post_meta(get_the_ID(), '_wp_attachment_image_alt', get_the_title());
			}
		}
	}
}


/********************************************************
**  ON UPLOAD SET MINIMAL ALT TAG IN IMAGES
********************************************************/
add_action( 'add_attachment', 'sagive_automate_imgalt' );
function sagive_automate_imgalt( $img_id ) {

	// is this an image?
	if ( wp_attachment_is_image( $img_id ) ) {
		$imgTitle = get_post( $img_id )->post_title;
		$imgTitle = preg_replace( '%\s*[-_\s]+\s*%', ' ',  $imgTitle );     // Removes hyphens, underscores etc
		$imgTitle = ucwords( strtolower( $imgTitle ) );                     // Capitaliztion etc

		// reset image title using formatted title
		$imgMeta = array(
			'ID'		    => $img_id,    
			'post_title'	=> $imgTitle,   
		);
		wp_update_post( $imgMeta );

		update_post_meta( $img_id, '_wp_attachment_image_alt', $imgTitle ); // Set the alt text
	} 
}
?>