Is the attribute background useless?

[ZhangChengLin]

Captcha/src/Gregwar/Captcha/CaptchaBuilder.php

Line 430 in a84b5b4

$this->background = $bg;

Is the background useless? It is still related to distort in line 480, because $bg in line 480 does not necessarily work.
I am not quite sure, so I dare not submit a PR rashly, please confirm.

Captcha/src/Gregwar/Captcha/CaptchaBuilder.php

Line 480 in a84b5b4

$image = $this->distort($image, $width, $height, $bg);

[visavi]

Yes, there is a problem with this, but you can turn off all the effects, then it will work

$builder->setBackgroundImages($backgrounds);
$builder->setIgnoreAllEffects(true);