在Python PIL中以可设置的中心和比例裁剪图像 [英] Crop image with settable center and scale in Python PIL
问题描述
我想使用PIL裁剪图像,尽管它可以是其他模块.我需要使用比例因子(即1.5)进行裁剪的方法,这意味着输出将被放大1.5倍.此外,我需要设置缩放的中心.这意味着将x/2,y/2设置为中心将直接缩放到中心,而其他x,y值将放大这些像素.
I would like to crop an image using PIL, although it could be some other module. I need the method to crop with a scale factor, ie 1.5 meaning that the output would be 1.5x zoomed in. Additionally, I would need to set the center where it zooms. This means setting x/2,y/2 as the center would zoom straight to the center, but other x,y values would zoom into those pixels.
如果有人知道该怎么做,我将非常感谢您的帮助.
If anyone knows how to do this I would really appreciate any help.
现在我使用ims = im.crop((int((xx/i)/2),int((yy/i)/2),int((x +(x/i)))进行裁剪/2),int(((y +(y/i))/2)))) 但这只会放大到中心,而"i"没有给出合适的比例因子.
Right now I have some cropping working with ims = im.crop((int((x-x/i)/2), int((y-y/i)/2), int((x+(x/i))/2), int((y+(y/i))/2))) but that only zooms into the center, and "i" doesn't give a nice scale factor.
再次感谢您的帮助.
推荐答案
这仅仅是确定中心和尺寸的问题.
It is just a matter of getting the center and the sizes right.
- 确定要修剪的点的中心
- 使用比例因子确定新尺寸
- 确定裁剪图像的边界框
下面的脚本应该可以解决问题.
The following script should do the trick.
import os.path
from PIL import Image
def get_img_dir():
src_dir = os.path.dirname(__file__)
img_dir = os.path.join(src_dir, '..', 'img')
return img_dir
def open_img():
img_dir = get_img_dir()
img_name = 'amsterdam.jpg'
full_img_path = os.path.join(img_dir, img_name)
img = Image.open(full_img_path)
return img
def crop_image(img, xy, scale_factor):
'''Crop the image around the tuple xy
Inputs:
-------
img: Image opened with PIL.Image
xy: tuple with relative (x,y) position of the center of the cropped image
x and y shall be between 0 and 1
scale_factor: the ratio between the original image's size and the cropped image's size
'''
center = (img.size[0] * xy[0], img.size[1] * xy[1])
new_size = (img.size[0] / scale_factor, img.size[1] / scale_factor)
left = max (0, (int) (center[0] - new_size[0] / 2))
right = min (img.size[0], (int) (center[0] + new_size[0] / 2))
upper = max (0, (int) (center[1] - new_size[1] / 2))
lower = min (img.size[1], (int) (center[1] + new_size[1] / 2))
cropped_img = img.crop((left, upper, right, lower))
return cropped_img
def save_img(img, img_name):
img_dir = get_img_dir()
full_img_path = os.path.join(img_dir, img_name)
img.save(full_img_path)
if __name__ == '__main__':
ams = open_img()
crop_ams = crop_image(ams, (0.50, 0.50), 0.95)
save_img(crop_ams, 'crop_amsterdam_01.jpg')
crop_ams = crop_image(ams, (0.25, 0.25), 2.5)
save_img(crop_ams, 'crop_amsterdam_02.jpg')
crop_ams = crop_image(ams, (0.75, 0.45), 3.5)
save_img(crop_ams, 'crop_amsterdam_03.jpg')
原始图片:
crop_amsterdam_01.jpg:
crop_amsterdam_01.jpg:
crop_amsterdam_02.jpg:
crop_amsterdam_02.jpg:
crop_amsterdam_03.jpg:
crop_amsterdam_03.jpg:
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