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import io
from PIL import Image, ImageFile
# Rescale an image in the form of bytes to a new set of bytes
# in the same format. Assumes the aspect is correct and that
# the incoming data is valid (it's expected to be for example
# the output of previous image operations)
def rescale_image_bytes(origbytes, resolution):
p = ImageFile.Parser()
p.feed(origbytes)
p.close()
img = p.image
return rescale_image(img, resolution)
def rescale_image(img, resolution, centered=False):
scale = min(
float(resolution[0]) / float(img.size[0]),
float(resolution[1]) / float(img.size[1]),
)
newimg = img.resize(
(int(img.size[0] * scale), int(img.size[1] * scale)),
Image.BICUBIC,
)
saver = io.BytesIO()
if centered and newimg.size[0] != newimg.size[1]:
# This is not a square, so we have to roll it again
centeredimg = Image.new('RGBA', resolution)
centeredimg.paste(newimg, (
(resolution[0] - newimg.size[0]) // 2,
(resolution[1] - newimg.size[1]) // 2,
))
centeredimg.save(saver, format='PNG')
else:
newimg.save(saver, format=img.format)
return saver.getvalue()
def get_image_contenttype_from_bytes(image):
if bytearray(image[:3]) == b'\xFF\xD8\xFF':
return 'image/jpeg'
elif bytearray(image[:8]) == b'\x89\x50\x4e\x47\x0d\x0a\x1a\x0a':
return 'image/png'
raise Exception("Could not determine image format")
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