Image resize on JPGs - resized image appears as tiny thumb on black background

[eluser]w1ntermut3[/eluser]
Yep, tried with no height set, with height set to 100, with no master_dim set, with master_dim set to auto, with maintain_ratio true and false... I just get a variation on the theme of "resized original on a black background".

I've given up and done it natively, BTW. This works fine:

Code:

$canvas = imagecreatetruecolor($new_width, $new_height);
$source = imagecreatefromjpeg($saved_file_full_path);
$success = imagecopyresized($canvas, $source, 0, 0, 0, 0, $new_width, $new_height, $upload_width, $upload_height);
imagejpeg($canvas, $saved_file_full_path);