Populate image title, alt-text, caption, and description on upload

functions.php

<?php
// Do not include the opening php tag.

// Populate image title, alt-text, caption, and description on upload
add_action( 'add_attachment', 'crt_set_image_meta' );
function crt_set_image_meta( $post_ID ) {

	// Check if uploaded file is an image, else do nothing
	if ( wp_attachment_is_image( $post_ID ) ) {

		// Set image meta to 'Status: Date'
		$timezone = get_option('timezone_string');
		date_default_timezone_set( $timezone );
		$image_title = 'Status: '.date( 'Y-m-d H.i.s' );
		$image_meta = array(

			'ID'		=> $post_ID,
			'post_title'	=> $image_title,
			'post_excerpt'	=> $image_title,
			'post_content'	=> $image_title,

		);

		// Set the image alt-text
		update_post_meta( $post_ID, '_wp_attachment_image_alt', $image_title );

		// Set the image meta
		wp_update_post( $image_meta );

	}

}