Python 向图像添加填充以使它们具有相同的形状
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Add padding to images to get them into the same shape
提问by vincent
l have a set of images of different sizes (45,50,3), (69,34,3), (34,98,3). l want to add padding to these images as follows:
我有一组不同大小的图像(45,50,3), (69,34,3), (34,98,3)。我想为这些图像添加填充，如下所示：
Take the max width and length of the whole images then put the image in that size
获取整个图像的最大宽度和长度，然后将图像放入该尺寸
import os
import glob
import cv2
input_path="/home/images"
os.chdir(indput_path)
images=glob.glob("*.png")
Length=[]
Width=[]
for img in images:
img=cv2.imread(img)
width,length=img.shape[0:2]
Length.append(length)
Width.append(width)
W=max(Width)
L=max(Length)
How can l add padding in opencv so that all the images will have the same size? In the example l gave the images will get the shape of (69,98,3)
我如何在 opencv 中添加填充以使所有图像都具有相同的大小？在我给出的例子中，图像将得到形状(69,98,3)
回答by Azade Farshad
You can use:
您可以使用：
image = cv2.copyMakeBorder( src, top, bottom, left, right, borderType)
where src is your source image and top, botto, left, right are paddings around the image.
其中 src 是您的源图像，顶部、底部、左侧、右侧是图像周围的填充。
You can use max(sizes) - size value of the image in a while loop to add the padding to each image. the bordertype can be one of these:
您可以在 while 循环中使用 max(sizes) - 图像的大小值将填充添加到每个图像。边界类型可以是以下之一：
- cv2.BORDER_CONSTANT
- cv2.BORDER_REFLECT
- cv2.BORDER_REFLECT_101
- cv2.BORDER_DEFAULT
- cv2.BORDER_REPLICATE
- cv2.BORDER_WRAP
- cv2.BORDER_CONSTANT
- cv2.BORDER_REFLECT
- cv2.BORDER_REFLECT_101
- cv2.BORDER_DEFAULT
- cv2.BORDER_REPLICATE
- cv2.BORDER_WRAP
回答by fmw42
Here is another way to do that in Python/OpenCV/Numpy. It uses numpy slicing to copy the input image into a new image of the desired output size and a given offset. Here I compute the offset to do center padding. I think this is easier to do using width, height, xoffset, yoffset, rather than how much to pad on each side.
这是在 Python/OpenCV/Numpy 中执行此操作的另一种方法。它使用 numpy 切片将输入图像复制到具有所需输出大小和给定偏移量的新图像中。在这里，我计算偏移量以进行中心填充。我认为使用宽度、高度、xoffset、yoffset 更容易做到这一点，而不是每边填充多少。
Input:
输入：
import cv2
import numpy as np
# read image
img = cv2.imread('lena.jpg')
ht, wd, cc= img.shape
# create new image of desired size and color (blue) for padding
ww = 300
hh = 300
color = (255,0,0)
result = np.full((hh,ww,cc), color, dtype=np.uint8)
# compute center offset
xx = (ww - wd) // 2
yy = (hh - ht) // 2
# copy img image into center of result image
result[yy:yy+ht, xx:xx+wd] = img
# view result
cv2.imshow("result", result)
cv2.waitKey(0)
cv2.destroyAllWindows()
# save result
cv2.imwrite("lena_centered.jpg", result)
回答by sivi
Like this (Padding is called borders on openCV):
像这样（填充在 openCV 上称为边框）：
BLUE = [255,255,255]
constant= cv2.copyMakeBorder(image.copy(),10,10,10,10,cv2.BORDER_CONSTANT,value=BLUE)
And blue can become white even
蓝色甚至可以变成白色
source: https://docs.opencv.org/3.4/da/d0c/tutorial_bounding_rects_circles.html
来源：https: //docs.opencv.org/3.4/da/d0c/tutorial_bounding_rects_circles.html
回答by George Sotiropoulos
As I do not see an accepted answer, and also the fact that one has to determine the top, bottom, left, right of the function, I have bellow what worked for me easily. Taken from: https://jdhao.github.io/2017/11/06/resize-image-to-square-with-padding/
由于我没有看到可接受的答案，而且还必须确定函数的顶部、底部、左侧、右侧，因此我很容易找到对我有用的方法。摘自：https: //jdhao.github.io/2017/11/06/resize-image-to-square-with-padding/
import cv2
desired_size = 368
im_pth = "/home/jdhao/test.jpg"
im = cv2.imread(im_pth)
old_size = im.shape[:2] # old_size is in (height, width) format
ratio = float(desired_size)/max(old_size)
new_size = tuple([int(x*ratio) for x in old_size])
# new_size should be in (width, height) format
im = cv2.resize(im, (new_size[1], new_size[0]))
delta_w = desired_size - new_size[1]
delta_h = desired_size - new_size[0]
top, bottom = delta_h//2, delta_h-(delta_h//2)
left, right = delta_w//2, delta_w-(delta_w//2)
color = [0, 0, 0]
new_im = cv2.copyMakeBorder(im, top, bottom, left, right, cv2.BORDER_CONSTANT,
value=color)
cv2.imshow("image", new_im)
cv2.waitKey(0)
cv2.destroyAllWindows()
回答by Ismael EL ATIFI
Here is a function doing all for you :
这是一个为您完成所有工作的功能：
import cv2
def pad_images_to_same_size(images):
"""
:param images: sequence of images
:return: list of images padded so that all images have same width and height (max width and height are used)
"""
width_max = 0
height_max = 0
for img in images:
h, w = img.shape[:2]
width_max = max(width_max, w)
height_max = max(height_max, h)
images_padded = []
for img in images:
h, w = img.shape[:2]
diff_vert = height_max - h
pad_top = diff_vert//2
pad_bottom = diff_vert - pad_top
diff_hori = width_max - w
pad_left = diff_hori//2
pad_right = diff_hori - pad_left
img_padded = cv2.copyMakeBorder(img, pad_top, pad_bottom, pad_left, pad_right, cv2.BORDER_CONSTANT, value=0)
assert img_padded.shape[:2] == (height_max, width_max)
images_padded.append(img_padded)
return images_padded
回答by Wei Li
try to use this function:
尝试使用此功能：
from PIL import Image, ImageOps
def padding(img, expected_size):
desired_size = expected_size
delta_width = desired_size - img.size[0]
delta_height = desired_size - img.size[1]
pad_width = delta_width // 2
pad_height = delta_height // 2
padding = (pad_width, pad_height, delta_width - pad_width, delta_height - pad_height)
return ImageOps.expand(img, padding)
def resize_with_padding(img, expected_size):
img.thumbnail((expected_size[0], expected_size[1]))
# print(img.size)
delta_width = expected_size[0] - img.size[0]
delta_height = expected_size[1] - img.size[1]
pad_width = delta_width // 2
pad_height = delta_height // 2
padding = (pad_width, pad_height, delta_width - pad_width, delta_height - pad_height)
return ImageOps.expand(img, padding)
if __name__ == "__main__":
img = Image.open("./demo.jpg")
print(img)
img = resize_with_padding(img, (500, 400))
print(img.size)
img.show()
img.save("resized_img.jpg")
see https://gist.github.com/BIGBALLON/cb6ab73f6aaaa068ab6756611bb324b2
见https://gist.github.com/BIGBALLON/cb6ab73f6aaaa068ab6756611bb324b2
