Source

File: wp-includes/media.php

function wp_expand_dimensions( $example_width, $example_height, $max_width, $max_height ) {
	$example_width  = (int) $example_width;
	$example_height = (int) $example_height;
	$max_width      = (int) $max_width;
	$max_height     = (int) $max_height;

	return wp_constrain_dimensions( $example_width * 1000000, $example_height * 1000000, $max_width, $max_height );
}