使用python和imagemagick附加图像

Question

Most people recommend "wand" when it comes to imagemagick for python but how can I append images using it in python ? I want to add lables to bottom of images using imagemagick in python : http://www.imagemagick.org/Usage/annotating/ but wand api seems to be very basic and doesn't have lots of imgemagick commands including labels and appending.

Is there any other way to use imagemagick in python ? my images are png type and are BytesIO streams inside the python code not files so I can not pass them to imagemagick using command line and can't save them on any temporary file either.

Answer 1

I'm not really sure what your asking for, but I'm guessing you want to write a label "below" an image. Here's an example with the wand library.

from wand.image import Image
from wand.compat import nested
from wand.color import Color
from wand.font import Font

with nested(Image(filename='logo:'),
            Image(filename='null:')) as (source, text):
    text.font = Font('Impact', 64)
    text.read(filename='label:Hello world!')
    largest_width = max(source.width, text.width)
    offset = (largest_width - min(source.width, text.width)) / 2
    with Image(width=largest_width,
               height=source.height + text.height,
               background=Color('WHITE')) as dst:
        dst.composite(source, 0, 0)
        dst.composite(text, int(offset), source.height)
        dst.save(filename="output.png")

Overview

with nested(Image(filename='logo:'),
            Image(filename='null:')) as (source, text):

Create two images. You would be responsible for replacing logo: image with your ByteIO buffer. The null: image is a placeholder for allocating a wand instance.

    text.font = Font('Impact', 64)
    text.read(filename='label:Hello world!')

This defines the typeface & text to draw. The label: protocol can be replaced with caption: for additional behavior(s?).

    with Image(width=largest_width,
               height=source.height + text.height,
               background=Color('WHITE')) as dst:

Create a third "blank" image that is large enough to include both images.

        dst.composite(source, 0, 0)
        dst.composite(text, int(offset), source.height)

Copy the image data from the source & text to the new image.

Answer 2

Imagemagick is great but has steep learning curve. You need to have 3rd party ImageMagick installed (Would have to be 32 or 64 bit depending on your version of python). Installation alone is a pain considering you need to add it to path and the executable is necessary to run your script.

Consider something more portable and contained like Pillow which has number of features for achieving your goal.

pip install pillow

In pillow you can read images from BytesIO. And also draw or print on them. There is number of options available.

from PIL import Image, ImageDraw
import io


# Reading bytes from file but you can skip that and simply open your bytes like below.

with open('picture.jpg', 'rb') as f:
    im = Image.open(io.BytesIO(f.read()))
    draw = ImageDraw.Draw(im)
    draw.text((10,10), "Hello World", fill=(255))
    im.show() # do whatever you like with the image

Check the docs for more examples. https://pillow.readthedocs.io/en/latest/