python 批量图片resize代码——分别3种库函数实现

浅浅的花香味﹌ 2022-03-16 09:42 559阅读 0赞

### 一.1.opencv:      cv2 ###

'cv2'
    import cv2
    import os
    import glob
    
    path = r'C:\Users\87419\Desktop\cg1\img\*.jpg'
    for i in glob.glob(path):
        im1 = cv2.imread(i)
        im2 = cv2.resize(im1,(256,256))
        cv2.imwrite(os.path.join(r'C:\Users\87419\Desktop\cg1\resize',os.path.basename(i)),im2)

### 2.matplotlib ：  from matplotlib import pyplot as plt ###

'plt, PIL '
    'plt本身无法实现resize， 故不推荐此方法(得到的图是带白边的)'
    import matplotlib.pyplot as plt
    import os
    import glob
    from PIL import Image
    
    path = r'C:\Users\87419\Desktop\cg1\img\*.jpg'
    for i in glob.glob(path):
        im1 = Image.open(i)
        im2 = im1.resize((256,256))
    
        plt.imshow(im2)
        plt.axis('off')
        plt.savefig(os.path.join(r'C:\Users\87419\Desktop\cg1\resize',os.path.basename(i)))

### 3. PIL：  from PIL import Image ###

'PIL'
    from PIL import Image
    import os
    import glob
    
    path = r'C:\Users\87419\Desktop\cg1\img\*.jpg'
    for i in glob.glob(path):
        im1 = Image.open(i)
        im2 = im1.resize((256,256))
        im2.save(os.path.join(r'C:\Users\87419\Desktop\cg1\resize',os.path.basename(i)))

可能会遇到报错 OSError: cannot write mode P as JPEG

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5OTM4NjY2_size_16_color_FFFFFF_t_70][]

解决方法  如下(其余格式报错同理，按 if img.mode == "P" or img.mode == "RGBA":  统一转为RGB就可以了)

import os
    from PIL import Image
    
    def resize_image():
        # 获取输入文件夹中的所有文件
        files = os.listdir(r'C:\Users\admin\Desktop\drone\beijing')
        output_dir = r'C:\Users\admin\Desktop\drone\bj_416'
    
        if not os.path.exists(output_dir):
            os.makedirs(output_dir)
    
        for file in files:
            img = Image.open(r'C:\Users\admin\Desktop\drone\beijing/' + file)
            if img.mode == "P" or img.mode == "RGBA":
                img = img.convert('RGB')
            img = img.resize((416, 416), Image.ANTIALIAS)
            img.save(os.path.join(output_dir, file))
    
    resize_image()

详解见  [https://blog.csdn.net/z704630835/article/details/84968767][https_blog.csdn.net_z704630835_article_details_84968767]

### 二.按指定图像位置裁剪 ###

以按中心位置抠出128\*128大小为例：

先

import os
    import cv2
    
    # 遍历指定目录，显示目录下的所有文件名
    def CropImage4File(filepath, destpath):
        pathDir = os.listdir(filepath)  # list all the path or file  in filepath
        for allDir in pathDir:
            child = os.path.join(filepath, allDir)
            dest = os.path.join(destpath, allDir)
    
            if os.path.isfile(child):
                image = cv2.imread(child)
                sp = image.shape  # obtain the image shape
                sz1 = sp[0]  # height(rows) of image
                sz2 = sp[1]  # width(colums) of image         
                a = int(sz1 / 2 - 600)  # x start
                b = int(sz1 / 2 + 300)  # x end
                c = int(sz2 / 2 - 450)  # y start
                d = int(sz2 / 2 + 450)  # y end
                cropImg = image[a:b, c:d]  # crop the image
                cv2.imwrite(dest, cropImg)  # write in destination path
    
    if __name__ == '__main__':
        filepath = r'C:\Users\admin\Desktop\1\01'  # source images
        destpath = r'C:\Users\admin\Desktop\1\02'  # resized images saved here
        CropImage4File(filepath, destpath)

再

'cv2'
    import cv2
    import os
    import glob
    
    path = r'C:\Users\admin\Desktop\1\02\*.jpg'
    for i in glob.glob(path):
        im1 = cv2.imread(i)
        im2 = cv2.resize(im1, (128, 128))
        cv2.imwrite(os.path.join(r'C:\Users\admin\Desktop\1\r_128', os.path.basename(i)), im2)

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5OTM4NjY2_size_16_color_FFFFFF_t_70]: /images/20220316/b09f6fadc44b4b9bb1189ffb92402c78.png
[https_blog.csdn.net_z704630835_article_details_84968767]: https://blog.csdn.net/z704630835/article/details/84968767