问题描述
为了后续处理目的,我在python中将多页PDF( f
)转换为JPEG格式( temp?.jpg
):
For subsequent processing purposes, in python I am converting a multi-page PDF (f
) into JPEGs (temp?.jpg
):
import os
from wand.image import Image as wimage
with wimage(filename=f,resolution=300) as img:
for i in range(len(img.sequence)):
ftemp=os.path.abspath('temp%i.jpg'%i)
img_to_save=wimage(img.sequence[i])
img_to_save.compression_quality = 100
img_to_save.format='jpeg'
img_to_save.save(filename=ftemp)
我正在使用魔杖,因为它能够对PDF页面进行排序,但我对PIL开放了等等。
I am using wand because of its ability to sequence the PDF pages, but am open to PIL etc.
我需要分辨率
和 compression_quality
来尽可能高,但我希望每个JPEG不大于(比方说)300 kb。
I need the resolution
and compression_quality
to be as high as possible, but I want each JPEG to be no larger than (say) 300 kb in size.
如何设置限制大小为JPEG文件?
How can I set a limit to the size of the JPEG file?
在命令行上我会做(见):
On the command line I would just do (see https://stackoverflow.com/a/11920384/1021819):
convert original.jpeg -define jpeg:extent=300kb -scale 50% output.jpg
谢谢!
推荐答案
库有 wand.image.OptionDict
用于管理 -define
属性,但遗憾的是所有选项都被 wand.image.Option
frozenset锁定。 恕我直言,这会使整个功能无法使用。
The wand library has wand.image.OptionDict
for managing -define
attributes, but unfortunately all options are locked by wand.image.Option
frozenset. IMHO, this renders the whole feature as unusable.
幸运的是,你可以通过<$ c创建一个快速的子类来处理这个问题。 $ c> wand.api 。
Luckily, you can create a quick sub-class to handle this via the wand.api
.
import os
from wand.image import Image
from wand.api import library
from wand.compat import binary
class wimage(Image):
def myDefine(self, key, value):
""" Skip over wand.image.Image.option """
return library.MagickSetOption(self.wand, binary(key), binary(value))
with wimage(filename=f, resolution=300) as img:
for i in range(len(img.sequence)):
ftemp=os.path.abspath('temp%i.jpg'%i)
with wimage(img.sequence[i]) as img_to_save:
img_to_save.myDefine('jpeg:extent', '300kb')
img_to_save.compression_quality = 100
img_to_save.format='jpeg'
img_to_save.save(filename=ftemp)
在不久的将来。 wand.image。选项
将被弃用,您只需调用 img_to_save.options ['jpeg:extent'] ='300kb'
。
In the near future. The wand.image.Option
would be deprecated, and you could simply call img_to_save.options['jpeg:extent'] = '300kb'
.
这篇关于python在使用例如转换(pdf)到jpeg时设置最大文件大小棍棒的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!