Image manipulation and processing using Python Modules and Packages
CV Python
CV
发布日期:   2019-10-14
文章字数:   330
阅读时长:   1 分
阅读次数:  

混杂知识点

1. 包，模块，库的区分

  • package：就是个带 init.py 的文件夹，并不在乎里面有什么，不过一般来讲会包含一些 packages/modules

  • module：一个 .py 文件就是个 module

  • lib：抽象概念，和另外两个不是一类，只要你喜欢，什么都是 lib，就算只有个 hello world, scrapy、flask、Django、numpy、scipy、NLTK、jieba，一般都被认为是 lib，因为关注点不是他们的代码是怎么组织的。

2. 图片格式转换

Numpy.array <=> PIL.Image

source

  • Numpy.array => PIL.Image : img = Image.fromarray(img)
  • PIL.Image => Numpy.array : img = np.array(img)

PIL.Image => Bytes:

source

from PIL import Image
import io

def image_to_byte_array(image:Image):
  imgByteArr = io.BytesIO()
  image.save(imgByteArr, format=image.format)
  imgByteArr = imgByteArr.getvalue()
  return imgByteArr

Bytes => Numpy.array

import requests
import matplotlib.pyplot as plt
img = requests.get(url).content
img = plt.imread(BytesIO(img), "jpg")

GIF ==> PNG

def iter_frames(gif):
    try:
        i= 0
        while 1:
            gif.seek(i)
            imframe = gif.copy()
            if i == 0:
                palette = imframe.getpalette()
            else:
                imframe.putpalette(palette)
            yield imframe
            i += 1
    except EOFError:
        pass
# http://cn.voidcc.com/question/p-ecfkyjoi-bks.html
# Bytes to GIF
# url = 'xxx'
# gif = Image.open(BytesIO(requests.get(url).content)))

gif = Image.open('captcha.gif')
for i, frame in enumerate(iter_frames(gif)):
  pass

3. 分离文件名与扩展名

source

import os
path_01='D:/User/wgy/workplace/data/notMNIST_large.tar.png'
path_02='D:/User/wgy/workplace/data/notMNIST_large'
root_01=os.path.splitext(path_01)
root_02=os.path.splitext(path_02)
print(root_01)
print(root_02)

结果：

('D:/User/wgy/workplace/data/notMNIST_large.tar', '.png')
('D:/User/wgy/workplace/data/notMNIST_large', '')

Numpy

PIL

Scipy

Open-cv

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