img.class.php is cropping the PNG image when using imagepng

[KiloooNL]

So this is a weird issue...

In img.class.php we use the banner image PNG, and do imagecreatefrompng($this->bannerImage);
however, for some reason upon imagepng($this->bannerImage); the PNG file gets slightly cropped at the bottom like so:

I can't seem to figure out why this is happening, it's not a memory issue, and doesn't seem to be a drawing issue, or issue with the PNG image.

[KiloooNL]

Update:
If we use extra arguments when doing imagepng(source, to, quality) then it draws a little bit more of the PNG image, but there's still a few pixels missing.