詳解python opencv、scikit-image和PIL影象處理庫比較
阿新 • • 發佈:2020-01-09
進行深度學習時,對影象進行預處理的過程是非常重要的,使用pytorch或者TensorFlow時需要對影象進行預處理以及展示來觀看處理效果,因此對python中的影象處理框架進行影象的讀取和基本變換的掌握是必要的,接下來python中幾個基本的影象處理庫進行縱向對比。
專案地址:https://github.com/Oldpan/Pytorch-Learn/tree/master/Image-Processing
比較的影象處理框架:
- PIL
- scikit-image
- opencv-python
PIL:
由於PIL僅支援到Python 2.7,加上年久失修,於是一群志願者在PIL的基礎上建立了相容的版本,名字叫Pillow,支援最新Python 3.x,又加入了許多新特性,因此,我們可以直接安裝使用Pillow。
摘自廖雪峰的官方網站
scikit-image
scikit-image is a collection of algorithms for image processing. It is available free of charge and free of restriction. We pride ourselves on high-quality,peer-reviewed code,written by an active community of volunteers.
摘自官網的介紹,scikit-image的更新還是比較頻繁的,程式碼質量也很好。
opencv-python
opencv的大名就不要多說了,這個是opencv的python版
# Compare Image-Processing Modules # Use Transforms Module of torchvision # &&& # 對比python中不同的影象處理模組 # 並且使用torchvision中的transforms模組進行影象處理 # packages from PIL import Image from skimage import io,transform import cv2 import torchvision.transforms as transforms import matplotlib.pyplot as plt %matplotlib inline img_PIL = Image.open('./images/dancing.jpg') img_skimage = io.imread('./images/dancing.jpg') img_opencv = cv2.imread('./images/dancing.jpg') img_plt = plt.imread('./images/dancing.jpg') loader = transforms.Compose([ transforms.ToTensor()]) # 轉換為torch.tensor格式 print('The shape of \n img_skimage is {}\n img_opencv is {}\n img_plt is {}\n'.format(img_skimage.shape,img_opencv.shape,img_plt.shape)) print('The type of \n img_skimage is {}\n img_opencv is {}\n img_plt is {}\n'.format(type(img_skimage),type(img_opencv),type(img_plt)))
The shape of img_skimage is (444,444,3) img_opencv is (444,3) img_plt is (444,3) The size of img_PIL is (444,444) The mode of img_PIL is RGB The type of img_skimage is <class 'numpy.ndarray'> img_opencv is <class 'numpy.ndarray'> img_plt is <class 'numpy.ndarray'> img_PIL if <class 'PIL.JpegImagePlugin.JpegImageFile'>
# 定義一個影象顯示函式 def my_imshow(image,title=None): plt.imshow(image) if title is not None: plt.title(title) plt.pause(0.001) # 這裡延時一下,否則影象無法載入 plt.figure() my_imshow(img_skimage,title='img_skimage') # 可以看到opencv讀取的影象打印出來的顏色明顯與其他不同 plt.figure() my_imshow(img_opencv,title='img_opencv') plt.figure() my_imshow(img_plt,title='img_plt') # opencv讀出的影象顏色通道為BGR,需要對此進行轉換 img_opencv = cv2.cvtColor(img_opencv,cv2.COLOR_BGR2RGB) plt.figure() my_imshow(img_opencv,title='img_opencv_new')
toTensor = transforms.Compose([transforms.ToTensor()]) # 尺寸變化、縮放 transform_scale = transforms.Compose([transforms.Scale(128)]) temp = transform_scale(img_PIL) plt.figure() my_imshow(temp,title='after_scale') # 隨機裁剪 transform_randomCrop = transforms.Compose([transforms.RandomCrop(32,padding=4)]) temp = transform_scale(img_PIL) plt.figure() my_imshow(temp,title='after_randomcrop') # 隨機進行水平翻轉(0.5機率) transform_ranHorFlip = transforms.Compose([transforms.RandomHorizontalFlip()]) temp = transform_scale(img_PIL) plt.figure() my_imshow(temp,title='after_ranhorflip') # 隨機裁剪到特定大小 transform_ranSizeCrop = transforms.Compose([transforms.RandomSizedCrop(128)]) temp = transform_ranSizeCrop(img_PIL) plt.figure() my_imshow(temp,title='after_ranSizeCrop') # 中心裁剪 transform_centerCrop = transforms.Compose([transforms.CenterCrop(128)]) temp = transform_centerCrop(img_PIL) plt.figure() my_imshow(temp,title='after_centerCrop') # 空白填充 transform_pad = transforms.Compose([transforms.Pad(4)]) temp = transform_pad(img_PIL) plt.figure() my_imshow(temp,title='after_padding') # 標準化是在整個資料集中對所有影象進行取平均和均方差,演示影象數量過少無法進行此操作 # print(train_data.mean(axis=(0,1,2))/255) # print(train_data.std(axis=(0,2))/255) # transform_normal = transforms.Compose([transforms.Normalize()]) # Lamdba使用使用者自定義函式來對影象進行剪裁 # transform_pad = transforms.Compose([transforms.Lambda()])
以上就是本文的全部內容,希望對大家的學習有所幫助,也希望大家多多支援我們。