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.

Answer 2

An easy solution is to change the order of commands: Change the format to jpeg first and then to resize

        img.format = 'jpeg'
        img.resize(dest_width, int(ratio * img.height))

It is also very easy to open the PDF in the exact size by the resolution tuple, because the resolution can be a float number.

Answer 3

For others who still have this problem I fixed it after googling and trying a couple of hours thanks to this question https://stackoverflow.com/a/40494320/2686243 by using this two lines:

img.background_color = Color("white")
img.alpha_channel = 'remove'

Tried with Wand version 0.4.4