blocks|key|864319|text|定义最大大小。然后，通过获取min(maxwidth/width,+maxheight/height)来计算调整比率。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|864320|合适的大小是oldsize*ratio。|864321|当然，还有一个库方法可以做到这一点：Image.thumbnail方法。|864322|下面是PIL+documentation中的一个(编辑过的)示例。|864323|import+os,+sys
import+Image

size+=+128,+128

for+infile+in+sys.argv[1:]:
++++outfile+=+os.path.splitext(infile)[0]+%2B+".thumbnail"
++++if+infile+!=+outfile:
++++++++try:
++++++++++++im+=+Image.open(infile)
++++++++++++im.thumbnail(size,+Image.ANTIALIAS)
++++++++++++im.save(outfile,+"JPEG")
++++++++except+IOError:
++++++++++++print+"cannot+create+thumbnail+for+'%25s'"+%25+infile|code-block|syntax|javascript|864324|entityMap|0|LINK|mutability|MUTABLE|url|http://effbot.org/imagingbook/introduction.htm^0|E|11|0|6|D|0|I|F|0|3|H|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|17|8|@]|D|@$9|18|A|19|1|1A]]|E|$]]|$1|L|3|M|5|N|7|1B|8|@]|D|@]|E|$O|P]]|$1|Q|3|-4|5|6|7|1C|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]]]

Define a maximum size.
Then, compute a resize ratio by taking <code>min(maxwidth/width, maxheight/height)</code>.

The proper size is <code>oldsize*ratio</code>.

There is of course also a library method to do this: the method <code>Image.thumbnail</code>. 
Below is an (edited) example from the <a href="http://effbot.org/imagingbook/introduction.htm" rel="noreferrer">PIL documentation</a>.

<pre><code>import os, sys
import Image

size = 128, 128

for infile in sys.argv[1:]:
 outfile = os.path.splitext(infile)[0] + ".thumbnail"
 if infile != outfile:
 try:
 im = Image.open(infile)
 im.thumbnail(size, Image.ANTIALIAS)
 im.save(outfile, "JPEG")
 except IOError:
 print "cannot create thumbnail for '%s'" % infile
</code></pre>

blocks|key|869723|text|如果您试图保持相同的纵横比，那么您不会将大小调整为原始大小的某个百分比吗？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|869724|例如，原始大小的一半|869725|half+=+0.5
out+=+im.resize(+[int(half+*+s)+for+s+in+im.size]+)|code-block|syntax|javascript|869726|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

If you are trying to maintain the same aspect ratio, then wouldn't you resize by some percentage of the original size?

For example, half the original size

<pre><code>half = 0.5
out = im.resize( [int(half * s) for s in im.size] )
</code></pre>

blocks|key|4068834|text|此脚本将使用PIL+(Python+image+Library)将图像(somepic.jpg)的大小调整为300像素的宽度和与新宽度成比例的高度。它通过确定300像素占原始宽度(img.size)的百分比，然后将原始高度(img.size1)乘以该百分比来实现此目的。将"basewidth“更改为任何其他数字，即可更改图像的默认宽度。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4068835|from+PIL+import+Image

basewidth+=+300
img+=+Image.open('somepic.jpg')
wpercent+=+(basewidth/float(img.size[0]))
hsize+=+int((float(img.size[1])*float(wpercent)))
img+=+img.resize((basewidth,hsize),+Image.ANTIALIAS)
img.save('somepic.jpg')|code-block|syntax|javascript|4068836|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This script will resize an image (somepic.jpg) using PIL (Python Imaging Library) to a width of 300 pixels and a height proportional to the new width. It does this by determining what percentage 300 pixels is of the original width (img.size[0]) and then multiplying the original height (img.size[1]) by that percentage. Change &quot;basewidth&quot; to any other number to change the default width of your images.
<pre><code>from PIL import Image

basewidth = 300
img = Image.open('somepic.jpg')
wpercent = (basewidth/float(img.size[0]))
hsize = int((float(img.size[1])*float(wpercent)))
img = img.resize((basewidth,hsize), Image.ANTIALIAS)
img.save('somepic.jpg')
</code></pre>

blocks|key|864428|text|我还推荐使用PIL的缩略图方法，因为它消除了所有的比率问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|864429|不过，有一个重要的提示:替换|864430|im.thumbnail(size)|code-block|syntax|javascript|864431|使用|864432|im.thumbnail(size,Image.ANTIALIAS)|864433|默认情况下，PIL使用Image.NEAREST过滤器来调整大小，这会导致良好的性能，但质量较差。|864434|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I also recommend using PIL's thumbnail method, because it removes all the ratio hassles from you.

One important hint, though: Replace

<pre><code>im.thumbnail(size)
</code></pre>

with

<pre><code>im.thumbnail(size,Image.ANTIALIAS)
</code></pre>

by default, PIL uses the Image.NEAREST filter for resizing which results in good performance, but poor quality.

blocks|key|990|text|我丑陋的例子。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|991|函数获取文件，如："pic0-9a-z.extension"，将其调整为120x120，将部分移动到中心并保存为"ico0-9a-z.extension"，适用于纵向和横向：|992|def+imageResize(filepath):
++++from+PIL+import+Image
++++file_dir=os.path.split(filepath)
++++img+=+Image.open(filepath)

++++if+img.size[0]+>+img.size[1]:
++++++++aspect+=+img.size[1]/120
++++++++new_size+=+(img.size[0]/aspect,+120)
++++else:
++++++++aspect+=+img.size[0]/120
++++++++new_size+=+(120,+img.size[1]/aspect)
++++img.resize(new_size).save(file_dir[0]%2B'/ico'%2Bfile_dir[1][3:])
++++img+=+Image.open(file_dir[0]%2B'/ico'%2Bfile_dir[1][3:])

++++if+img.size[0]+>+img.size[1]:
++++++++new_img+=+img.crop(+(
++++++++++++(((img.size[0])-120)/2),
++++++++++++0,
++++++++++++120%2B(((img.size[0])-120)/2),
++++++++++++120
++++++++)+)
++++else:
++++++++new_img+=+img.crop(+(
++++++++++++0,
++++++++++++(((img.size[1])-120)/2),
++++++++++++120,
++++++++++++120%2B(((img.size[1])-120)/2)
++++++++)+)

++++new_img.save(file_dir[0]%2B'/ico'%2Bfile_dir[1][3:])|code-block|syntax|javascript|993|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

My ugly example.

Function get file like: "pic[0-9a-z].[extension]", resize them to 120x120, moves section to center and save to "ico[0-9a-z].[extension]", works with portrait and landscape:

<pre><code>def imageResize(filepath):
 from PIL import Image
 file_dir=os.path.split(filepath)
 img = Image.open(filepath)

 if img.size[0] &gt; img.size[1]:
 aspect = img.size[1]/120
 new_size = (img.size[0]/aspect, 120)
 else:
 aspect = img.size[0]/120
 new_size = (120, img.size[1]/aspect)
 img.resize(new_size).save(file_dir[0]+'/ico'+file_dir[1][3:])
 img = Image.open(file_dir[0]+'/ico'+file_dir[1][3:])

 if img.size[0] &gt; img.size[1]:
 new_img = img.crop( (
 (((img.size[0])-120)/2),
 0,
 120+(((img.size[0])-120)/2),
 120
 ) )
 else:
 new_img = img.crop( (
 0,
 (((img.size[1])-120)/2),
 120,
 120+(((img.size[1])-120)/2)
 ) )

 new_img.save(file_dir[0]+'/ico'+file_dir[1][3:])
</code></pre>

blocks|key|1047|text|基于@tomvon，我使用了以下内容(选择您的案例)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1048|a)+调整高度(我知道新的宽度，所以我需要新的高度)|offset|length|style|BOLD|1049|new_width++=+680
new_height+=+new_width+*+height+/+width+|code-block|syntax|javascript|1050|b)+调整宽度(我知道新的高度，所以我需要新的宽度)|1051|new_height+=+680
new_width++=+new_height+*+width+/+height|1052|然后只需：|1053|img+=+img.resize((new_width,+new_height),+Image.ANTIALIAS)|1054|entityMap^0|0|3|4|0|0|3|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@$D|Y|E|Z|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|10|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|11|8|@$D|12|E|13|F|G]]|9|@]|A|$]]|$1|O|3|P|5|J|7|14|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|15|8|@]|9|@]|A|$]]|$1|S|3|T|5|J|7|16|8|@]|9|@]|A|$K|L]]|$1|U|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|V|$]]

Based in @tomvon, I finished using the following (pick your case):

a) Resizing height (I know the new width, so I need the new height)

<pre><code>new_width = 680
new_height = new_width * height / width 
</code></pre>

b) Resizing width (I know the new height, so I need the new width)

<pre><code>new_height = 680
new_width = new_height * width / height
</code></pre>

Then just:

<pre><code>img = img.resize((new_width, new_height), Image.ANTIALIAS)
</code></pre>

blocks|key|1101|text|from+PIL+import+Image
from+resizeimage+import+resizeimage

def+resize_file(in_file,+out_file,+size):
++++with+open(in_file)+as+fd:
++++++++image+=+resizeimage.resize_thumbnail(Image.open(fd),+size)
++++image.save(out_file)
++++image.close()

resize_file('foo.tif',+'foo_small.jpg',+(256,+256))|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1102|我使用这个库：|unstyled|1103|pip+install+python-resize-image|1104|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>from PIL import Image
from resizeimage import resizeimage

def resize_file(in_file, out_file, size):
 with open(in_file) as fd:
 image = resizeimage.resize_thumbnail(Image.open(fd), size)
 image.save(out_file)
 image.close()

resize_file('foo.tif', 'foo_small.jpg', (256, 256))
</code></pre>

I use this library:

<pre><code>pip install python-resize-image
</code></pre>

blocks|key|4069195|text|from+PIL+import+Image

img+=+Image.open('/your+image+path/image.jpg')+#+image+extension+*.png,*.jpg
new_width++=+200
new_height+=+300
img+=+img.resize((new_width,+new_height),+Image.ANTIALIAS)
img.save('output+image+name.png')+#+format+may+what+you+want+*.png,+*jpg,+*.gif|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4069196|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>from PIL import Image

img = Image.open('/your image path/image.jpg') # image extension *.png,*.jpg
new_width = 200
new_height = 300
img = img.resize((new_width, new_height), Image.ANTIALIAS)
img.save('output image name.png') # format may what you want *.png, *jpg, *.gif
</code></pre>

blocks|key|3222947|text|只是用一个更现代的包装器更新这个问题，这个库包装了Pillow+(PIL的一个分支)+https://pypi.org/project/python-resize-image/|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3222948|允许你做这样的事情：|3222949|from+PIL+import+Image
from+resizeimage+import+resizeimage

fd_img+=+open('test-image.jpeg',+'r')
img+=+Image.open(fd_img)
img+=+resizeimage.resize_width(img,+200)
img.save('test-image-width.jpeg',+img.format)
fd_img.close()|code-block|syntax|javascript|3222950|上面的链接中有更多的例子。|3222951|entityMap|0|LINK|mutability|MUTABLE|url|https://pypi.org/project/python-resize-image/^0|17|19|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|6|7|Y|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|Z|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|C|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

Just updating this question with a more modern wrapper
This library wraps Pillow (a fork of PIL)
<a href="https://pypi.org/project/python-resize-image/" rel="noreferrer">https://pypi.org/project/python-resize-image/</a>

Allowing you to do something like this :-

<pre><code>from PIL import Image
from resizeimage import resizeimage

fd_img = open('test-image.jpeg', 'r')
img = Image.open(fd_img)
img = resizeimage.resize_width(img, 200)
img.save('test-image-width.jpeg', img.format)
fd_img.close()
</code></pre>

Heaps more examples in the above link.

blocks|key|3223017|text|保持受约束的比率和传递最大宽度/高度的简单方法。不是最漂亮的，但可以完成工作，而且很容易理解：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3223018|def+resize(img_path,+max_px_size,+output_folder):
++++with+Image.open(img_path)+as+img:
++++++++width_0,+height_0+=+img.size
++++++++out_f_name+=+os.path.split(img_path)[-1]
++++++++out_f_path+=+os.path.join(output_folder,+out_f_name)

++++++++if+max((width_0,+height_0))+<=+max_px_size:
++++++++++++print('writing+{}+to+disk+(no+change+from+original)'.format(out_f_path))
++++++++++++img.save(out_f_path)
++++++++++++return

++++++++if+width_0+>+height_0:
++++++++++++wpercent+=+max_px_size+/+float(width_0)
++++++++++++hsize+=+int(float(height_0)+*+float(wpercent))
++++++++++++img+=+img.resize((max_px_size,+hsize),+Image.ANTIALIAS)
++++++++++++print('writing+{}+to+disk'.format(out_f_path))
++++++++++++img.save(out_f_path)
++++++++++++return

++++++++if+width_0+<+height_0:
++++++++++++hpercent+=+max_px_size+/+float(height_0)
++++++++++++wsize+=+int(float(width_0)+*+float(hpercent))
++++++++++++img+=+img.resize((max_px_size,+wsize),+Image.ANTIALIAS)
++++++++++++print('writing+{}+to+disk'.format(out_f_path))
++++++++++++img.save(out_f_path)
++++++++++++return|code-block|syntax|javascript|3223019|这是一个使用此函数运行批量图像调整大小的python+script。|offset|length|3223020|entityMap|0|LINK|mutability|MUTABLE|url|https://gist.github.com/agalea91/12149be6d4f64ba61c7b1d222fce3174^0|0|0|K|D|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

A simple method for keeping constrained ratios and passing a max width / height. Not the prettiest but gets the job done and is easy to understand:

<pre><code>def resize(img_path, max_px_size, output_folder):
 with Image.open(img_path) as img:
 width_0, height_0 = img.size
 out_f_name = os.path.split(img_path)[-1]
 out_f_path = os.path.join(output_folder, out_f_name)

 if max((width_0, height_0)) &lt;= max_px_size:
 print('writing {} to disk (no change from original)'.format(out_f_path))
 img.save(out_f_path)
 return

 if width_0 &gt; height_0:
 wpercent = max_px_size / float(width_0)
 hsize = int(float(height_0) * float(wpercent))
 img = img.resize((max_px_size, hsize), Image.ANTIALIAS)
 print('writing {} to disk'.format(out_f_path))
 img.save(out_f_path)
 return

 if width_0 &lt; height_0:
 hpercent = max_px_size / float(height_0)
 wsize = int(float(width_0) * float(hpercent))
 img = img.resize((max_px_size, wsize), Image.ANTIALIAS)
 print('writing {} to disk'.format(out_f_path))
 img.save(out_f_path)
 return
</code></pre>

Here's a <a href="https://gist.github.com/agalea91/12149be6d4f64ba61c7b1d222fce3174" rel="nofollow noreferrer">python script</a> that uses this function to run batch image resizing.

blocks|key|3223043|text|如果您不想/不需要使用Pillow打开图像，请使用以下命令：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3223044|from+PIL+import+Image

new_img_arr+=+numpy.array(Image.fromarray(img_arr).resize((new_width,+new_height),+Image.ANTIALIAS))|code-block|syntax|javascript|3223045|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you don't want / don't have a need to open image with Pillow, use this:

<pre><code>from PIL import Image

new_img_arr = numpy.array(Image.fromarray(img_arr).resize((new_width, new_height), Image.ANTIALIAS))
</code></pre>

blocks|key|864683|text|我试图为幻灯片视频调整一些图像的大小，正因为如此，我想要的不仅仅是一个最大尺寸，而是一个最大宽度和最大高度(视频帧的大小)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|864684|也总有可能出现肖像视频...|864685|Image.thumbnail方法很有前途，但我无法将其放大为较小的图像。|offset|length|style|CODE|864686|因此，当我在这里(或其他地方)找不到明显的方法后，我编写了这个函数，并将其放在这里以备将来使用：|864687|from+PIL+import+Image

def+get_resized_img(img_path,+video_size):
++++img+=+Image.open(img_path)
++++width,+height+=+video_size++#+these+are+the+MAX+dimensions
++++video_ratio+=+width+/+height
++++img_ratio+=+img.size[0]+/+img.size[1]
++++if+video_ratio+>=+1:++#+the+video+is+wide
++++++++if+img_ratio+<=+video_ratio:++#+image+is+not+wide+enough
++++++++++++width_new+=+int(height+*+img_ratio)
++++++++++++size_new+=+width_new,+height
++++++++else:++#+image+is+wider+than+video
++++++++++++height_new+=+int(width+/+img_ratio)
++++++++++++size_new+=+width,+height_new
++++else:++#+the+video+is+tall
++++++++if+img_ratio+>=+video_ratio:++#+image+is+not+tall+enough
++++++++++++height_new+=+int(width+/+img_ratio)
++++++++++++size_new+=+width,+height_new
++++++++else:++#+image+is+taller+than+video
++++++++++++width_new+=+int(height+*+img_ratio)
++++++++++++size_new+=+width_new,+height
++++return+img.resize(size_new,+resample=Image.LANCZOS)|code-block|syntax|javascript|864688|entityMap^0|0|0|0|F|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@$F|V|G|W|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|X|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|Y|8|@]|9|@]|A|$O|P]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I was trying to resize some images for a slideshow video and because of that, I wanted not just one max dimension, but a max width and a max height (the size of the video frame). 
And there was always the possibility of a portrait video... 
The <code>Image.thumbnail</code> method was promising, but I could not make it upscale a smaller image.

So after I couldn't find an obvious way to do that here (or at some other places), I wrote this function and put it here for the ones to come:

<pre><code>from PIL import Image

def get_resized_img(img_path, video_size):
 img = Image.open(img_path)
 width, height = video_size # these are the MAX dimensions
 video_ratio = width / height
 img_ratio = img.size[0] / img.size[1]
 if video_ratio &gt;= 1: # the video is wide
 if img_ratio &lt;= video_ratio: # image is not wide enough
 width_new = int(height * img_ratio)
 size_new = width_new, height
 else: # image is wider than video
 height_new = int(width / img_ratio)
 size_new = width, height_new
 else: # the video is tall
 if img_ratio &gt;= video_ratio: # image is not tall enough
 height_new = int(width / img_ratio)
 size_new = width, height_new
 else: # image is taller than video
 width_new = int(height * img_ratio)
 size_new = width_new, height
 return img.resize(size_new, resample=Image.LANCZOS)
</code></pre>

blocks|key|1386|text|我以这样的方式调整了图像的大小，它工作得非常好|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1387|from+io+import+BytesIO
from+django.core.files.uploadedfile+import+InMemoryUploadedFile
import+os,+sys
from+PIL+import+Image


def+imageResize(image):
++++outputIoStream+=+BytesIO()
++++imageTemproaryResized+=+imageTemproary.resize(+(1920,1080),+Image.ANTIALIAS)+
++++imageTemproaryResized.save(outputIoStream+,+format='PNG',+quality='10')+
++++outputIoStream.seek(0)
++++uploadedImage+=+InMemoryUploadedFile(outputIoStream,'ImageField',+"%25s.jpg"+%25+image.name.split('.')[0],+'image/jpeg',+sys.getsizeof(outputIoStream),+None)

++++##+For+upload+local+folder
++++fs+=+FileSystemStorage()
++++filename+=+fs.save(uploadedImage.name,+uploadedImage)|code-block|syntax|javascript|1388|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I resizeed the image in such a way and it's working very well

<pre><code>from io import BytesIO
from django.core.files.uploadedfile import InMemoryUploadedFile
import os, sys
from PIL import Image


def imageResize(image):
 outputIoStream = BytesIO()
 imageTemproaryResized = imageTemproary.resize( (1920,1080), Image.ANTIALIAS) 
 imageTemproaryResized.save(outputIoStream , format='PNG', quality='10') 
 outputIoStream.seek(0)
 uploadedImage = InMemoryUploadedFile(outputIoStream,'ImageField', "%s.jpg" % image.name.split('.')[0], 'image/jpeg', sys.getsizeof(outputIoStream), None)

 ## For upload local folder
 fs = FileSystemStorage()
 filename = fs.save(uploadedImage.name, uploadedImage)
</code></pre>

blocks|key|3223170|text|我已经通过"tomvon“更新了上面的答案|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3223171|from+PIL+import+Image

img+=+Image.open(image_path)

width,+height+=+img.size[:2]

if+height+>+width:
++++baseheight+=+64
++++hpercent+=+(baseheight/float(img.size[1]))
++++wsize+=+int((float(img.size[0])*float(hpercent)))
++++img+=+img.resize((wsize,+baseheight),+Image.ANTIALIAS)
++++img.save('resized.jpg')
else:
++++basewidth+=+64
++++wpercent+=+(basewidth/float(img.size[0]))
++++hsize+=+int((float(img.size[1])*float(wpercent)))
++++img+=+img.resize((basewidth,hsize),+Image.ANTIALIAS)
++++img.save('resized.jpg')|code-block|syntax|javascript|3223172|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Have updated the answer above by "tomvon"

<pre><code>from PIL import Image

img = Image.open(image_path)

width, height = img.size[:2]

if height &gt; width:
 baseheight = 64
 hpercent = (baseheight/float(img.size[1]))
 wsize = int((float(img.size[0])*float(hpercent)))
 img = img.resize((wsize, baseheight), Image.ANTIALIAS)
 img.save('resized.jpg')
else:
 basewidth = 64
 wpercent = (basewidth/float(img.size[0]))
 hsize = int((float(img.size[1])*float(wpercent)))
 img = img.resize((basewidth,hsize), Image.ANTIALIAS)
 img.save('resized.jpg')
</code></pre>

blocks|key|864728|text|打开您的图像文件|type|unstyled|depth|inlineStyleRanges|entityRanges|data|864729|from+PIL+import+Image
im+=+Image.open("image.png")|code-block|syntax|javascript|864730|Use+PIL+Image.resize(size,+resample=0)+method，您可以用图像的(宽度，高度)替换大小为2元组的图像。|offset|length|864731|这将以原始大小显示您的图像：|864732|display(im.resize((int(im.size[0]),int(im.size[1])),+0)+)|864733|这将以1/2的大小显示图像：|864734|display(im.resize((int(im.size[0]/2),int(im.size[1]/2)),+0)+)|864735|这将以1/3的大小显示图像：|864736|display(im.resize((int(im.size[0]/3),int(im.size[1]/3)),+0)+)|864737|这将以1/4的大小显示图像：|864738|display(im.resize((int(im.size[0]/4),int(im.size[1]/4)),+0)+)|864739|等等等等|864740|entityMap|0|LINK|mutability|MUTABLE|url|https://pillow.readthedocs.io/en/3.1.x/reference/Image.html#PIL.Image.Image.resize^0|0|0|0|19|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1C|8|@]|9|@$I|1D|J|1E|1|1F]]|A|$]]|$1|K|3|L|5|6|7|1G|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|1H|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|1I|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|1J|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|1K|8|@]|9|@]|A|$]]|$1|U|3|V|5|D|7|1L|8|@]|9|@]|A|$E|F]]|$1|W|3|X|5|6|7|1M|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|D|7|1N|8|@]|9|@]|A|$E|F]]|$1|10|3|11|5|6|7|1O|8|@]|9|@]|A|$]]|$1|12|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]]|13|$14|$5|15|16|17|A|$18|19]]]]

Open your image file 

<pre><code>from PIL import Image
im = Image.open("image.png")
</code></pre>

<a href="https://pillow.readthedocs.io/en/3.1.x/reference/Image.html#PIL.Image.Image.resize" rel="nofollow noreferrer">Use PIL Image.resize(size, resample=0) method</a>, where you substitute (width, height) of your image for the size 2-tuple.

This will display your image at original size:

<pre><code>display(im.resize((int(im.size[0]),int(im.size[1])), 0) )
</code></pre>

This will display your image at 1/2 the size:

<pre><code>display(im.resize((int(im.size[0]/2),int(im.size[1]/2)), 0) )
</code></pre>

This will display your image at 1/3 the size:

<pre><code>display(im.resize((int(im.size[0]/3),int(im.size[1]/3)), 0) )
</code></pre>

This will display your image at 1/4 the size:

<pre><code>display(im.resize((int(im.size[0]/4),int(im.size[1]/4)), 0) )
</code></pre>

etc etc

blocks|key|4069641|text|我还将添加一个保持宽高比不变的调整大小的版本。在这种情况下，它将根据初始纵横比asp_rat+(+float+(!)+)调整高度以匹配新图像的宽度。但是，要将宽度调整为高度，只需在else循环中注释一行并取消对另一行的注释。你将会看到，在哪里。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|4069642|你不需要分号(;)，我保留它们只是为了提醒我自己更常用的语言的语法。|4069643|from+PIL+import+Image

img_path+=+"filename.png";
img+=+Image.open(img_path);+++++#+puts+our+image+to+the+buffer+of+the+PIL.Image+object

width,+height+=+img.size;
asp_rat+=+width/height;

#+Enter+new+width+(in+pixels)
new_width+=+50;

#+Enter+new+height+(in+pixels)
new_height+=+54;

new_rat+=+new_width/new_height;

if+(new_rat+==+asp_rat):
++++img+=+img.resize((new_width,+new_height),+Image.ANTIALIAS);+

#+adjusts+the+height+to+match+the+width
#+NOTE:+if+you+want+to+adjust+the+width+to+the+height,+instead+->+
#+uncomment+the+second+line+(new_width)+and+comment+the+first+one+(new_height)
else:
++++new_height+=+round(new_width+/+asp_rat);
++++#new_width+=+round(new_height+*+asp_rat);
++++img+=+img.resize((new_width,+new_height),+Image.ANTIALIAS);

#+usage:+resize((x,y),+resample)
#+resample+filter+->+PIL.Image.BILINEAR,+PIL.Image.NEAREST+(default),+PIL.Image.BICUBIC,+etc..
#+https://pillow.readthedocs.io/en/3.1.x/reference/Image.html#PIL.Image.Image.resize

#+Enter+the+name+under+which+you+would+like+to+save+the+new+image
img.save("outputname.png");|code-block|syntax|javascript|4069644|而且，它已经完成了。我试着尽可能多地记录下来，所以很清楚。|4069645|我希望它能对外面的人有所帮助！|4069646|entityMap^0|1D|5|2I|4|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|Z|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|10|8|@]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|R|$]]

I will also add a version of the resize that keeps the aspect ratio fixed.
In this case, it will adjust the height to match the width of the new image, based on the initial aspect ratio, asp_rat, which is float (!). 
But, to adjust the width to the height, instead, you just need to comment one line and uncomment the other in the else loop. You will see, where.

You do not need the semicolons (;), I keep them just to remind myself of syntax of languages I use more often.

<pre><code>from PIL import Image

img_path = "filename.png";
img = Image.open(img_path); # puts our image to the buffer of the PIL.Image object

width, height = img.size;
asp_rat = width/height;

# Enter new width (in pixels)
new_width = 50;

# Enter new height (in pixels)
new_height = 54;

new_rat = new_width/new_height;

if (new_rat == asp_rat):
 img = img.resize((new_width, new_height), Image.ANTIALIAS); 

# adjusts the height to match the width
# NOTE: if you want to adjust the width to the height, instead -&gt; 
# uncomment the second line (new_width) and comment the first one (new_height)
else:
 new_height = round(new_width / asp_rat);
 #new_width = round(new_height * asp_rat);
 img = img.resize((new_width, new_height), Image.ANTIALIAS);

# usage: resize((x,y), resample)
# resample filter -&gt; PIL.Image.BILINEAR, PIL.Image.NEAREST (default), PIL.Image.BICUBIC, etc..
# https://pillow.readthedocs.io/en/3.1.x/reference/Image.html#PIL.Image.Image.resize

# Enter the name under which you would like to save the new image
img.save("outputname.png");
</code></pre>

And, it is done. I tried to document it as much as I can, so it is clear. 

I hope it might be helpful to someone out there!

blocks|key|3223288|text|import+cv2
from+skimage+import+data+
import+matplotlib.pyplot+as+plt
from+skimage.util+import+img_as_ubyte
from+skimage+import+io
filename='abc.png'
image=plt.imread(filename)
im=cv2.imread('abc.png')
print(im.shape)
im.resize(300,300)
print(im.shape)
plt.imshow(image)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3223289|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>import cv2
from skimage import data 
import matplotlib.pyplot as plt
from skimage.util import img_as_ubyte
from skimage import io
filename='abc.png'
image=plt.imread(filename)
im=cv2.imread('abc.png')
print(im.shape)
im.resize(300,300)
print(im.shape)
plt.imshow(image)
</code></pre>

blocks|key|864794|text|下面的脚本创建了所有JPEG图像的漂亮缩略图，保留了最大分辨率为128x128的纵横比。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|864795|from+PIL+import+Image
img+=+Image.open("D:\\Pictures\\John.jpg")
img.thumbnail((680,680))
img.save("D:\\Pictures\\John_resize.jpg")|code-block|syntax|javascript|864796|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The following script creates nice thumbnails of all JPEG images preserving aspect ratios with 128x128 max resolution.
<pre><code>from PIL import Image
img = Image.open(&quot;D:\\Pictures\\John.jpg&quot;)
img.thumbnail((680,680))
img.save(&quot;D:\\Pictures\\John_resize.jpg&quot;)
</code></pre>

blocks|key|4069739|text|如果调整大小的限制仅限于一个维度(宽或高)，则可以将PIL的Image.thumbnail与sys.maxsize结合使用。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4069740|例如，如果您想调整图像的大小，使其高度不超过100px，同时保持纵横比，您可以这样做：|4069741|import+sys
from+PIL+import+Image

image.thumbnail([sys.maxsize,+100],+Image.ANTIALIAS)|code-block|syntax|javascript|4069742|请记住，Image.thumbnail将就地调整图像的大小，这与返回调整后的图像而不更改原始图像的Image.resize不同。|4069743|entityMap|0|LINK|mutability|MUTABLE|url|https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.thumbnail|1|https://stackoverflow.com/a/9860611/738017^0|U|F|1A|B|U|F|0|1A|B|1|0|0|0|4|F|1D|C|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@$9|13|A|14|1|15]|$9|16|A|17|1|18]]|E|$]]|$1|F|3|G|5|6|7|19|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1A|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1B|8|@$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|1G|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]|W|$5|R|S|T|E|$U|X]]]]

You can combine PIL's <a href="https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.thumbnail" rel="nofollow noreferrer"><code>Image.thumbnail</code></a> with <a href="https://stackoverflow.com/a/9860611/738017"><code>sys.maxsize</code></a> if your resize limit is only on one dimension (width or height).
For instance, if you want to resize an image so that its height is no more than 100px, while keeping aspect ratio, you can do something like this:
<pre><code>import sys
from PIL import Image

image.thumbnail([sys.maxsize, 100], Image.ANTIALIAS)
</code></pre>
Keep in mind that <code>Image.thumbnail</code> will resize the image in place, which is different from <code>Image.resize</code> that instead returns the resized image without changing the original one.

blocks|key|3223414|text|对我来说最简单的方法就是|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3223415|image+=+image.resize((image.width*2,+image.height*2),+Image.ANTIALIAS)|code-block|syntax|javascript|3223416|示例|3223417|from+PIL+import+Image,+ImageGrab
image+=+ImageGrab.grab(bbox=(0,0,400,600))+#take+screenshot
image+=+image.resize((image.width*2,+image.height*2),+Image.ANTIALIAS)
image.save('Screen.png')|3223418|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

The simplest way that worked for me
<pre><code>image = image.resize((image.width*2, image.height*2), Image.ANTIALIAS)
</code></pre>
Example
<pre><code>from PIL import Image, ImageGrab
image = ImageGrab.grab(bbox=(0,0,400,600)) #take screenshot
image = image.resize((image.width*2, image.height*2), Image.ANTIALIAS)
image.save('Screen.png')
</code></pre>

blocks|key|1702|text|若要使新图像的宽度和高度分别为原始图像的一半，请使用以下代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1703|++from+PIL+import+Image
++im+=+Image.open("image.jpg")
++resized_im+=+im.resize((round(im.size[0]*0.5),+round(im.size[1]*0.5)))
++++
++#Save+the+cropped+image
++resized_im.save('resizedimage.jpg')|code-block|syntax|javascript|1704|要使用定量调整固定宽度的大小，请执行以下操作：|1705|from+PIL+import+Image
new_width+=+300
im+=+Image.open("img/7.jpeg")
concat+=+int(new_width/float(im.size[0]))
size+=+int((float(im.size[1])*float(concat)))
resized_im+=+im.resize((new_width,size),+Image.ANTIALIAS)
#Save+the+cropped+image
resized_im.save('resizedimage.jpg')|1706|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

To make the new image half the width and half the height of the original image, Use below code :
<pre><code> from PIL import Image
 im = Image.open(&quot;image.jpg&quot;)
 resized_im = im.resize((round(im.size[0]*0.5), round(im.size[1]*0.5)))
 
 #Save the cropped image
 resized_im.save('resizedimage.jpg')
</code></pre>
To resize with fixed width with ration:
<pre><code>from PIL import Image
new_width = 300
im = Image.open(&quot;img/7.jpeg&quot;)
concat = int(new_width/float(im.size[0]))
size = int((float(im.size[1])*float(concat)))
resized_im = im.resize((new_width,size), Image.ANTIALIAS)
#Save the cropped image
resized_im.save('resizedimage.jpg')
</code></pre>

blocks|key|1708|text|#+Importing+Image+class+from+PIL+module
from+PIL+import+Image

#+Opens+a+image+in+RGB+mode
im+=+Image.open(r"C:\Users\System-Pc\Desktop\ybear.jpg")

#+Size+of+the+image+in+pixels+(size+of+original+image)
#+(This+is+not+mandatory)
width,+height+=+im.size

#+Setting+the+points+for+cropped+image
left+=+4
top+=+height+/+5
right+=+154
bottom+=+3+*+height+/+5

#+Cropped+image+of+above+dimension
#+(It+will+not+change+original+image)
im1+=+im.crop((left,+top,+right,+bottom))
newsize+=+(300,+300)
im1+=+im1.resize(newsize)
#+Shows+the+image+in+image+viewer
im1.show()|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1709|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code># Importing Image class from PIL module
from PIL import Image

# Opens a image in RGB mode
im = Image.open(r&quot;C:\Users\System-Pc\Desktop\ybear.jpg&quot;)

# Size of the image in pixels (size of original image)
# (This is not mandatory)
width, height = im.size

# Setting the points for cropped image
left = 4
top = height / 5
right = 154
bottom = 3 * height / 5

# Cropped image of above dimension
# (It will not change original image)
im1 = im.crop((left, top, right, bottom))
newsize = (300, 300)
im1 = im1.resize(newsize)
# Shows the image in image viewer
im1.show()
</code></pre>

blocks|key|1711|text|######get+resize+coordinate+after+resize+the+image+using+this+function#####
def+scale_img_pixel(points,original_dim,resize_dim):
++++++++multi_list+=+[points]
++++++++new_point_list+=+[]
++++++++multi_list_point+=+[]
++++++++for+point+in+multi_list:
++++++++++++multi_list_point.append([point[0],point[1]])
++++++++++++multi_list_point.append([point[2],point[3]])
++++++++for+lsingle_point+in+multi_list_point:
++++++++++++x1+=+int((lsingle_point[0]+*+(resize_dim[0]+/+original_dim[0])))
++++++++++++y1+=+int((lsingle_point[1]+*+(resize_dim[1]+/+original_dim[1])))
++++++++++++new_point_list.append(x1)
++++++++++++new_point_list.append(y1)
++++++++++++
++++++++return+new_point_list
++++
++++
++++points+=+[774,265,909,409]
++++original_dim+=+(1237,1036)
++++resize_dim+=+(640,480)
++++result+=+scale_img_pixel(points,original_dim,resize_dim)
++++print("result:+",+result)++|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1712|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>######get resize coordinate after resize the image using this function#####
def scale_img_pixel(points,original_dim,resize_dim):
 multi_list = [points]
 new_point_list = []
 multi_list_point = []
 for point in multi_list:
 multi_list_point.append([point[0],point[1]])
 multi_list_point.append([point[2],point[3]])
 for lsingle_point in multi_list_point:
 x1 = int((lsingle_point[0] * (resize_dim[0] / original_dim[0])))
 y1 = int((lsingle_point[1] * (resize_dim[1] / original_dim[1])))
 new_point_list.append(x1)
 new_point_list.append(y1)
 
 return new_point_list
 
 
 points = [774,265,909,409]
 original_dim = (1237,1036)
 resize_dim = (640,480)
 result = scale_img_pixel(points,original_dim,resize_dim)
 print(&quot;result: &quot;, result) 
</code></pre>

Is there an obvious way to do this that I'm missing? I'm just trying to make thumbnails.

How do I resize an image using PIL and maintain its aspect ratio?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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有没有什么明显的方法可以解决我没有注意到的问题呢？我只是想做些缩略图。

问如何使用PIL调整图像大小并保持其纵横比？
EN

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问如何使用PIL调整图像大小并保持其纵横比？EN