Python Wand converts from PDF to JPG background is incorrect

Question

I found a so wired thing while converting a pdf to jpeg, so i\'d like to figure out that maybe this is a small bug. See the converted jpg below, you could find that, the bac

Answer 1

I got the answer by myself. It's because of the alpha_channel case. This pdf includes some transparent background(after i transfomred to png format), and for resize, ImageMagick choose the best resize filter, so black background displayed.

So, after a lot of experiments, I found that just add "img.alpha_channel=False" in "with" statement(before img.save()), that would work properly.

Thanks for VadimR's advise, it is helpful.