python 下载图片到内存卡_python - 获取图像大小而不将图像加载到内存中
如果您不關(guān)心圖像內(nèi)容，PIL可能是一種過度殺傷力。
我建議解析python magic模塊的輸出：
>>> t = magic.from_file('teste.png')
>>> t
'PNG image data, 782 x 602, 8-bit/color RGBA, non-interlaced'
>>> re.search('(\d+) x (\d+)', t).groups()
('782', '602')
這是libmagic的包裝器，它讀取盡可能少的字節(jié)以識別文件類型簽名。
相關(guān)版本的腳本：
[https://raw.githubusercontent.com/scardine/image_size/master/get_image_size.py]
[更新]
嗯，不幸的是，當(dāng)應(yīng)用于jpegs時，上面給出了''JPEG圖像數(shù)據(jù)，EXIF標準2.21'“。 沒有圖像尺寸！ - 亞歷克斯弗林特
看起來像jpegs是魔法抗性的。:-)
我明白為什么：為了獲得JPEG文件的圖像尺寸，你可能需要閱讀比libmagic喜歡的字節(jié)。
卷起袖子，帶著這個非常未經(jīng)測試的片段(從GitHub獲取)，不需要第三方模塊。
#-------------------------------------------------------------------------------
# Name: get_image_size
# Purpose: extract image dimensions given a file path using just
# core modules
#
# Author: Paulo Scardine (based on code from Emmanuel VA?SSE)
#
# Created: 26/09/2013
# Copyright: (c) Paulo Scardine 2013
# Licence: MIT
#-------------------------------------------------------------------------------
#!/usr/bin/env python
import os
import struct
class UnknownImageFormat(Exception):
pass
def get_image_size(file_path):
"""
Return (width, height) for a given img file content - no external
dependencies except the os and struct modules from core
"""
size = os.path.getsize(file_path)
with open(file_path) as input:
height = -1
width = -1
data = input.read(25)
if (size >= 10) and data[:6] in ('GIF87a', 'GIF89a'):
# GIFs
w, h = struct.unpack("
width = int(w)
height = int(h)
elif ((size >= 24) and data.startswith('\211PNG\r\n\032\n')
and (data[12:16] == 'IHDR')):
# PNGs
w, h = struct.unpack(">LL", data[16:24])
width = int(w)
height = int(h)
elif (size >= 16) and data.startswith('\211PNG\r\n\032\n'):
# older PNGs?
w, h = struct.unpack(">LL", data[8:16])
width = int(w)
height = int(h)
elif (size >= 2) and data.startswith('\377\330'):
# JPEG
msg = " raised while trying to decode as JPEG."
input.seek(0)
input.read(2)
b = input.read(1)
try:
while (b and ord(b) != 0xDA):
while (ord(b) != 0xFF): b = input.read(1)
while (ord(b) == 0xFF): b = input.read(1)
if (ord(b) >= 0xC0 and ord(b) <= 0xC3):
input.read(3)
h, w = struct.unpack(">HH", input.read(4))
break
else:
input.read(int(struct.unpack(">H", input.read(2))[0])-2)
b = input.read(1)
width = int(w)
height = int(h)
except struct.error:
raise UnknownImageFormat("StructError" + msg)
except ValueError:
raise UnknownImageFormat("ValueError" + msg)
except Exception as e:
raise UnknownImageFormat(e.__class__.__name__ + msg)
else:
raise UnknownImageFormat(
"Sorry, don't know how to get information from this file."
)
return width, height
總結(jié)
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