image processing - python set maximum file size when converting (pdf) to jpeg using e.g. Wand -


for subsequent processing purposes, in python converting multi-page pdf (f) jpegs (temp?.jpg):

import os wand.image import image wimage  wimage(filename=f,resolution=300) img:     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)

i using wand because of ability sequence pdf pages, open pil etc.

i need resolution , compression_quality high possible, want each jpeg no larger (say) 300 kb in size.

how can set limit size of jpeg file?

on command line (see https://stackoverflow.com/a/11920384/1021819):

convert original.jpeg -define jpeg:extent=300kb -scale 50% output.jpg

thanks!

the library has wand.image.optiondict managing -define attributes, unfortunately options locked wand.image.option frozenset. imho, renders whole feature unusable.

luckily, can create quick sub-class handle via wand.api.

import os wand.image import image wand.api import library wand.compat import binary  class wimage(image):     def mydefine(self, key, value):         """ skip on wand.image.image.option """         return library.magicksetoption(self.wand, binary(key), binary(value))   wimage(filename=f, resolution=300) img:     in range(len(img.sequence)):         ftemp=os.path.abspath('temp%i.jpg'%i)         wimage(img.sequence[i]) 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)

in near future. wand.image.option deprecated, , call img_to_save.options['jpeg:extent'] = '300kb'.


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