UNTESTED - Gravity Forms Image Upload Resizer

gravity-forms-file-upload-image-resizer.php

<?php

// Gravity Forms Image Upload Resizer. Replace _1 with your Form ID
add_action( "gform_after_submission_1", "gf_resize_images", 10, 2 );
function gf_resize_images( $entry, $form )
{
	// Replace 2 with field ID of upload field
	$url =  $entry[2];
	$parsed_url = parse_url( $url );
	$path = $_SERVER['DOCUMENT_ROOT'] . $parsed_url['path'];
	$image = wp_get_image_editor( $path );
	if ( ! is_wp_error( $image ) )
	{
		// Replace 800,600 with desired dimensions. If smaller, no crop applied.
		$result = $image->resize( 800, 600, false );
		$result = $image->save($path);
	}
}

?>