WordPres function to detect if an image is a portrait, by aspect ratio

sjf_deh_is_portrait.php

<?php

/**
 * Given an attachment_id and a definition of portraiture, detect if a photo is a portrait
 *
 * @param int 		$attachment_id	the attachment_id for the image
 * @param mixed 	$max_ratio	the aspect ratio that defines portraiture
 * @return boolean	returns true if image is a portrait, otherwise returns false
 */
function sjf_deh_is_portrait( $attachment_id, $max_ratio='.67' ){

	// if the attachment id is not an int, bail
	if( !is_int( $attachment_id ) ) { return false; }
	
	// if the max ratio is not a float or an int, bail
	if( !is_numeric( $max_ratio ) ) { return false; }
	
	// get the width height of the image
	$att_src_array = wp_get_attachment_image_src( $attachment_id, 'full' );
	if( !is_array( $att_src_array ) ) { return false; }
	$width = $att_src_array[1];
	$height = $att_src_array[2];

	// given a height and a max aspect ratio, the threshold_width is the maximum width the image can be, and still be a portrait 
	$threshold_width = $max_ratio * $height;
	
	// if the image is narrower than the threshold width, it's a portrait
	if( $width < $threshold_width ) { return true; }

	return false;
}