Python Magickwand pdf to image converting and resize the image

Question

I need to create thumbnails of pdf files, and I am using Imagemagick to achieve that.

I have tried Pythonmagick and wand to convert the pdf to an image. However, when I try to resize the converted pdf, the resulting image becomes black.

Is there any option to set -define pdf:use-cropbox=true using python wrappers?

Is there any other method in Python to convert a pdf to a thumbnail?

The code is as follows:

    import wand
    img = wand.image.Image(filename="d:\\test.pdf[0]")
    img.resize(160,160)
    img.save(filename="d:\\test.jpg")

score 5 · Answer 1 · answered Oct 28 '12 at 08:36

5

I found work around for this problem. Convert pdf into image 1st and save the image. open newly saved image and and resize it.

import wand
img = wand.image.Image(filename="d:\\test.pdf[0]")
img.save(filename="d:\\temp.jpg")
img = wand.image.Image(filename="d:\\temp.jpg")
img.resize(160,160)
img.save(filename="d:\\resized_image.jpg")

I am still waiting for better answer.

answered Oct 28 '12 at 08:36

user1725030

143
1
7

1

I would suggest that the intermediate saving to "d:\\temp.jpg" used a lossless format so as not to introduce any extra compression artefacts into the final image. – awatts Dec 03 '12 at 12:14

score 2 · Answer 2 · answered Nov 26 '18 at 18:45

I faced the same problem today. I found another solution in other post. The reason why the image turns to black is that the background is transparent in PDF file. Since JPG file cannot recognize the alpha-channel (which record the transparent pixel information). JPG files will set those transparent pixel into black as default.

# Use the following two lines to fix this error
# img_page.background_color = Color('white')
# img_page.alpha_channel = 'remove'

with Image(filename="file.pdf",resolution= 350) as img_pdf:
    num_pages = len(img_pdf.sequence)
    for page, img in enumerate(img_pdf.sequence):
        img_page = Image(image=img)
        img_page.background_color = Color('white')
        img_page.alpha_channel = 'remove'
        img_page.resize(900,1200)
        img_page.save(filename="file"+str(page)+".jpg")
        if page == 0:
            img_page.resize(500, 500)
            img_page.save(filename="thumbnail.jpg")

ref: Python Wand convert PDF to PNG disable transparent (alpha_channel)

The calls to `resize` are likely to distort the dimensions of the images. If they're going to be displayed on a web page, better to constrain the either the height or the width (but not both) there. — Tom Russell, Mar 18 '23 at 05:38

score 0 · Answer 3 · answered Dec 28 '15 at 14:45

You can do it without using temporary files - if you don't depend on JPG.

The following works for me:

import wand
img=wand.image.Image(filename="/home/vagrant/tmp/wand/law.pdf[0]")
img.format='png'
img.resize(220,220)
img.save(filename="/home/vagrant/tmp/wand/law_2.png")

Python Magickwand pdf to image converting and resize the image

3 Answers3