WooCommerce | Thumbnail upscale & correct crop in WordPress

woocommerce-small-image-thumbnail-cropping.php

<?php

/*  Upscale images that are otherwise too small for thumbnail cropping */
function gc_thumbnail_upscale( $default, $orig_w, $orig_h, $new_w, $new_h, $crop ){
	if ( !$crop ) return null; // let the WordPress default function handle this
	
	$aspect_ratio = $orig_w / $orig_h;
	$size_ratio = max($new_w / $orig_w, $new_h / $orig_h);
	
	$crop_w = round($new_w / $size_ratio);
	$crop_h = round($new_h / $size_ratio);
	
	$s_x = floor( ($orig_w - $crop_w) / 2 );
	$s_y = floor( ($orig_h - $crop_h) / 2 );
	
	return array( 0, 0, (int) $s_x, (int) $s_y, (int) $new_w, (int) $new_h, (int) $crop_w, (int) $crop_h );
}
add_filter( 'image_resize_dimensions', 'gc_thumbnail_upscale', 10, 6 );