Programmatically Creating Thumbnails in Wordpress Displays Image As Binary - php

Question

I'm attempting to upload images into Wordpress programmatically. Everything is working except the last 2 lines where I attempt to generate image thumbnails and other intermediate sizes. The function, wp_generate_attachment_metadata(), appears to be correctly generating the new image sizes, but it then tries to display the resulting image as binary instead of returning the appropriate meta data array. Why is the binary (see image below) being echoed onto my screen? How do I suppress it?
$filetype = wp_check_filetype( basename( $image ), null );
$attachment = array(
'guid' => wp_upload_dir()['url'] . '/' . basename( $image ),
'post_mime_type' => $filetype['type'],
'post_content' => '',
'post_status' => 'inherit',
'post_title' => preg_replace( '/\.[^.]+$/', '', basename( $image ) )
);
$attach_id = wp_insert_attachment( $attachment, $image );
update_field('image', $attach_id, $post_id);
$attach_data = wp_generate_attachment_metadata( $attach_id, $image );
$response = wp_update_attachment_metadata( $attach_id, $attach_data );
This is a sampling of the binary echoed.

Answer 1

So it turns out that after the gibberish the function was displaying, was a short error message (failed to open stream: HTTP wrapper does
not support writeable connections). It turns out, the function "wp_generate_attachment_metadata" requires an absolute path to the image. Changing the $image variable to an absolute path (from a web path, http://website.com/path/to/image.png) fixed the issue.