Python实现图片长宽比例缩放和填充
作者：互联网
图片的大小(KB)也可以更改, 但是某些格式不太好操作, 我自己没发现啥比较好的办法, 所以暂时是放弃这一部分
PNG格式和JPG格式的区别应该就是图层吧, 导致对PNG更改大小(KB) 做不到我想要的效果, 这些我不是很专业, 所以也不太清楚
1 '''
2 : 一个缩略图程序， 不需要的部分可以去掉
3 : 主要实现了尺寸(长宽)和大小(KB)的缩小
4 '''
5 import cv2
6 import os.path
7 from PIL import Image
8 from psd_tools import PSDImage
9
10
11 class ChangeSize:
12
13 def __init__(self, out_width, out_height, start_path, output_path, limit_size=100):
14 '''
15 :param start_path: 输入图片地址
16 :param limit_size: 输出图片大小(KB)
17 :param out_width: 输出图片宽度
18 :param out_height: 输出图片高度
19 '''
20 self.out_width = out_width
21 self.out_height = out_height
22 self.limit_size = limit_size
23 self.start_path = start_path
24 self.output_path = output_path
25 print("start_path: ", self.start_path)
26 print("output_path: ", self.output_path)
27
28 def get_image(self):
29 self.suffix = self.start_path.rsplit("\\", 1)[-1].rsplit(".", 1)[-1]
30
31 if self.suffix == "exr": # 如果是exr, 单独处理
32 self.tmp_path = mk_tmp_dir() # 创建临时文件夹
33 self.temp_exr = self.tmp_path + "/temp_exr.hdr" # 先转换成hdr
34 img_read = cv2.imread(self.start_path, cv2.IMREAD_UNCHANGED)
35 cv2.imwrite(self.temp_exr, img_read)
36 return self.get_temp_obj()
37 elif self.suffix == "psd":
38 self.tmp_path = mk_tmp_dir()
39 self.temp_psd = self.tmp_path + "/temp_psd.png"
40 psd = PSDImage.open(self.start_path)
41 psd.compose().save(self.temp_psd)
42 return self.get_temp_obj()
43 else: # 其他格式图片正常处理
44 img_read = cv2.imread(self.start_path)
45 if img_read is None:
46 print("---Read Img Failed---")
47 else:
48 print("缩略图程序读取图片成功")
49 return img_read
50
51 def get_temp_obj(self):
52 '''
53 用于需要转换格式的中转函数. exr, psd 等图片不能直接转换格式, 需要中转格式
54 :return: cv2 img Object
55 '''
56 if self.suffix == "exr":
57 img_read = cv2.imread(self.temp_exr)
58 return img_read
59 # if self.suffix == "psd":
60 # img_read = cv2.imread(self.temp_psd)
61 # return img_read
62
63 def get_resize_img(self, img):
64 '''
65 在这里转换尺寸, 保留原来尺寸比
66 :param img: cv2.img_Object
67 '''
68 size = img.shape
69 h, w = size[0], size[1]
70 print(w, h)
71
72 if h == w:
73 longest = h
74 scale = longest / float(self.out_height)
75 new_h, new_w = int(h / scale), int(w / scale)
76 print(new_w, new_h)
77 resize_img = self.fill_blank(img=img, new_w=new_w, new_h=new_h)
78 return resize_img
79 elif w > h:
80 longest = w
81 scale = longest / float(self.out_width)
82 new_h, new_w = int(h / scale), int(w / scale)
83 if new_h > self.out_height:
84 longest1 = h
85 scale1 = longest1 / float(self.out_height)
86 new_h_1, new_w_1 = int(h / scale1), int(w / scale1)
87 resize_img = self.fill_blank(img=img, new_w=new_w_1, new_h=new_h_1)
88 return resize_img
89 resize_img = self.fill_blank(img=img, new_w=new_w, new_h=new_h) # 填充空白部分为黑色
90 return resize_img
91
92 elif h > w:
93 longest = h
94 scale = longest / float(self.out_height)
95 new_h, new_w = int(h / scale), int(w / scale)
96 print(new_w, new_h)
97 if new_w > self.out_width:
98 longest1 = w
99 scale1 = longest1 / float(self.out_width)
100 new_h_1, new_w_1 = int(h / scale1), int(w / scale1)
101 resize_img = self.fill_blank(img=img, new_w=new_w_1, new_h=new_h_1)
102 return resize_img
103 resize_img = self.fill_blank(img=img, new_w=new_w, new_h=new_h)
104 return resize_img
105 else:
106 print("---未知错误---")
107
108 def fill_blank(self, img, new_w, new_h):
109 '''
110 :param img: 拿到cv2.imread() 返回的对象
111 :param new_w: 未补空白的时的宽度
112 :param new_h: 未补空白的时的高度
113 :return: 返回补空白后的对象（该对象用来写入）
114 '''
115 resize_img1 = cv2.resize(img, (new_w, new_h))
116 if new_w % 2 != 0 and new_h % 2 == 0:
117 top, bottom, left, right = (self.out_height - new_h) / 2, (self.out_height - new_h) / 2, (
118 self.out_width - new_w) / 2 + 1, (self.out_width - new_w) / 2
119 elif new_h % 2 != 0 and new_w % 2 == 0:
120 top, bottom, left, right = (self.out_height - new_h) / 2 + 1, (self.out_height - new_h) / 2, (
121 self.out_width - new_w) / 2, (self.out_width - new_w) / 2
122 elif new_h % 2 == 0 and new_w % 2 == 0:
123 top, bottom, left, right = (self.out_height - new_h) / 2, (self.out_height - new_h) / 2, (self.out_width - new_w) / 2, (
124 self.out_width - new_w) / 2
125 else:
126 top, bottom, left, right = (self.out_height - new_h) / 2 + 1, (self.out_height - new_h) / 2, (
127 self.out_width - new_w) / 2 + 1, (self.out_width - new_w) / 2
128 resize_img = cv2.copyMakeBorder(resize_img1, int(top), int(bottom), int(left), int(right), cv2.BORDER_CONSTANT,
129 value=[0, 0, 0])
130 # 从图像边界向上,下,左,右扩的像素数目
131 # cv2.imwrite("img_out/finally_w.jpg", pad_img)
132 return resize_img
133
134 def limit_size(self, quality=80, step=5):
135 """
136 图片尺寸压缩到指定大小(KB), 注意, 有些图片格式压缩不了. 此方法暂时废弃
137 :param step: 每次调整的压缩比率
138 :param quality: 初始压缩比率
139 :return: 压缩文件地址，压缩文件大小
140 """
141 file_size = os.path.getsize(self.tmp_file) / 1024
142 print("size: ", file_size, "limit_size: ", self.limit_size)
143 im = Image.open(self.tmp_file)
144 if file_size < self.limit_size:
145 im.save(self.output_file)
146 return
147 while file_size > self.limit_size:
148 im.save(self.output_file, quality=quality)
149 if quality - step < 0:
150 break
151 quality -= step
152 o_size = os.path.getsize(self.output_file) / 1024
153 return o_size
154
155 def main(self):
156 img_obj = self.get_image()
157 img_obj1 = self.get_resize_img(img_obj)
158 cv2.imwrite(output, img_obj1)
159 # cv2.imwrite(output, img_read, [cv2.IMWRITE_PNG_COMPRESSION, 1])
160 print("---缩略图程序完成---")
161
162
163 def rm_tmp_dir(start_path=None):
164 '''
165 移除临时文件夹
166 '''
167 savePath = current_path = os.getcwd()
168 tmp_path = savePath + "/tmp"
169 try:
170 import shutil
171 if os.path.exists(tmp_path): # 如果文件存在
172 print("临时文件夹存在, 开始删除")
173 shutil.rmtree(tmp_path, ignore_errors=True)
174 else:
175 print('no such file:%s' % tmp_path) # 则返回文件不存在
176 except Exception as rm_tmpdir_error:
177 print(rm_tmpdir_error)
178
179
180 def mk_tmp_dir():
181 current_path = os.getcwd()
182 tmp_path = os.path.join(current_path, "tmp")
183 if not os.path.exists(tmp_path):
184 os.mkdir(tmp_path)
185 return tmp_path
186
187
188 if __name__ == "__main__":
189 path = r"C:\Users\Administrator\Desktop\update\enjinecgrender\timg (8).jpg"
190 output = os.path.join(os.getcwd(), "output.png")
191 handle = ChangeSize(480, 320, path, output)
192 handle.main()
标签：tmp,长宽,img,缩放,Python,self,path,new,out 来源： https://www.cnblogs.com/MasonHu/p/13930230.html