blocks|key|1430186|text|ImageOps.expand函数将扩展图像，但它会在每个方向上添加相同数量的像素。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1430187|最好的方法是简单地制作一个新图像并粘贴：|1430188|newImage+=+Image.new(mode,+(newWidth,newHeight))
newImage.paste(srcImage,+(x1,y1,x1%2BoldWidth,y1%2BoldHeight))|code-block|syntax|javascript|1430189|如果性能有问题，请使原始图像大于所需大小，并在绘制完成后对其进行裁剪。|1430190|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

The ImageOps.expand function will expand the image, but it adds the same amount of pixels in each direction.

The best way is simply to make a new image and paste:

<pre><code>newImage = Image.new(mode, (newWidth,newHeight))
newImage.paste(srcImage, (x1,y1,x1+oldWidth,y1+oldHeight))
</code></pre>

If performance is an issue, make your original image bigger than needed and crop it after the drawing is done.

blocks|key|1430228|text|你可能会考虑用一种完全不同的方法来处理你的形象。使用固定大小的瓷砖构建它。这样，当您需要扩展时，只需添加新的图像块即可。完成所有计算后，可以确定图像的最终大小，创建该大小的空白图像，并将平铺粘贴到其中。这应该会减少你为完成任务而寻找的复制量。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1430229|(当然，您可能希望将这样的平铺图像封装到一个对象中，从而对其他代码层隐藏平铺方面。)|1430230|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

You might consider a rather different approach to your image... build it out of tiles of a fixed size. That way, as you need to expand, you just add new image tiles. When you have completed all of your computation, you can determine the final size of the image, create a blank image of that size, and paste the tiles into it. That should reduce the amount of copying you're looking at for completing the task.

(You'd likely want to encapsulate such a tiled image into an object that hid the tiling aspects from the other layers of code, of course.)

blocks|key|1215431|text|基于interjays答案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1215432|#!/usr/bin/env+python

from+PIL+import+Image
import+math


def+resize_canvas(old_image_path="314.jpg",+new_image_path="save.jpg",
++++++++++++++++++canvas_width=500,+canvas_height=500):
++++"""
++++Resize+the+canvas+of+old_image_path.

++++Store+the+new+image+in+new_image_path.+Center+the+image+on+the+new+canvas.

++++Parameters
++++----------
++++old_image_path+:+str
++++new_image_path+:+str
++++canvas_width+:+int
++++canvas_height+:+int
++++"""
++++im+=+Image.open(old_image_path)
++++old_width,+old_height+=+im.size

++++#+Center+the+image
++++x1+=+int(math.floor((canvas_width+-+old_width)+/+2))
++++y1+=+int(math.floor((canvas_height+-+old_height)+/+2))

++++mode+=+im.mode
++++if+len(mode)+==+1:++#+L,+1
++++++++new_background+=+(255)
++++if+len(mode)+==+3:++#+RGB
++++++++new_background+=+(255,+255,+255)
++++if+len(mode)+==+4:++#+RGBA,+CMYK
++++++++new_background+=+(255,+255,+255,+255)

++++newImage+=+Image.new(mode,+(canvas_width,+canvas_height),+new_background)
++++newImage.paste(im,+(x1,+y1,+x1+%2B+old_width,+y1+%2B+old_height))
++++newImage.save(new_image_path)

resize_canvas()|code-block|syntax|javascript|1215433|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|$]]

Based on interjays answer:

<pre><code>#!/usr/bin/env python

from PIL import Image
import math


def resize_canvas(old_image_path="314.jpg", new_image_path="save.jpg",
 canvas_width=500, canvas_height=500):
 """
 Resize the canvas of old_image_path.

 Store the new image in new_image_path. Center the image on the new canvas.

 Parameters
 ----------
 old_image_path : str
 new_image_path : str
 canvas_width : int
 canvas_height : int
 """
 im = Image.open(old_image_path)
 old_width, old_height = im.size

 # Center the image
 x1 = int(math.floor((canvas_width - old_width) / 2))
 y1 = int(math.floor((canvas_height - old_height) / 2))

 mode = im.mode
 if len(mode) == 1: # L, 1
 new_background = (255)
 if len(mode) == 3: # RGB
 new_background = (255, 255, 255)
 if len(mode) == 4: # RGBA, CMYK
 new_background = (255, 255, 255, 255)

 newImage = Image.new(mode, (canvas_width, canvas_height), new_background)
 newImage.paste(im, (x1, y1, x1 + old_width, y1 + old_height))
 newImage.save(new_image_path)

resize_canvas()
</code></pre>

blocks|key|1215467|text|此代码将放大较小的图像，保留纵横比，然后在标准大小的画布上居中。还会保留透明度，或默认为灰色背景。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1215468|已使用P模式PNG文件进行测试。|1215469|用于测试的编码调试final.show()和break。删除要循环并保存的final.save(...)上的行和标签。|offset|length|style|CODE|1215470|可以参数化画布比例和提高灵活性，但它达到了我的目的。|1215471|"""
Resize+...+and+reconfigures.+images+in+a+specified+directory

Use+case:++Images+of+varying+size,+need+to+be+enlarged+to+exaxtly+1200+x+1200
"""
import+os
import+glob

from+PIL+import+Image

#+Source+directory+plus+Glob+file+reference+(Windows)
source_path+=+os.path.join('C:',+os.sep,+'path',+'to',+'source',+'*.png')

#+List+of+UNC+Image+File+paths
images+=+glob.glob(source_path)

#+Destination+directory+of+modified+image+(Windows)
destination_path+=+os.path.join('C:',+os.sep,+'path',+'to',+'destination')

for+image+in+images:
++++
++++original+=+Image.open(image)

++++#+Retain+original+attributes+(ancillary+chunks)
++++info+=+original.info
++++
++++#+Retain+original+mode
++++mode+=+original.mode

++++#+Retain+original+palette
++++if+original.palette+is+not+None:
++++++++palette+=+original.palette.getdata()[1]
++++else:
++++++++palette+=+False

++++#+Match+original+aspect+ratio
++++dimensions+=+original.getbbox()

++++#+Identify+destination+image+background+color
++++if+'transparency'+in+info.keys():
++++++++background+=+original.info['transparency']
++++else:
++++++++#+Image+does+not+have+transparency+set
++++++++print(image)
++++++++background+=+(64)

++++#+Get+base+filename+and+extension+for+destination
++++filename,+extension+=+os.path.basename(image).split('.')
++++
++++#+Calculate+matched+aspect+ratio
++++if+dimensions[2]+>+dimensions[3]:
++++++++width+=+int(1200)
++++++++modifier+=+width+/+dimensions[2]
++++++++length+=+int(dimensions[3]+*+modifier)
++++elif+dimensions[3]+>+dimensions[2]:
++++++++length+=+int(1200)
++++++++modifier+=+length+/+dimensions[3]
++++++++width+=+int(dimensions[2]+*+modifier)
++++else:
++++++++width,+length+=+(1200,+1200)
++++
++++size+=+(width,+length)

++++#+Set+desired+final+image+size
++++canvas+=+(1200,+1200)
++++
++++#+Calculate+center+position
++++position+=+(
++++++++int((1200+-+width)/2),
++++++++int((1200+-+length)/2),
++++++++int((1200+-+width)/2)+%2B+width,
++++++++int((1200+-+length)/2)+%2B+length
++++)

++++#+Enlarge+original+image+proportionally
++++resized+=+original.resize(size,+Image.LANCZOS)

++++#+Then+create+sized+canvas
++++final+=+Image.new(mode,+canvas,+background)

++++#+Replicate+original+properties
++++final.info+=+info

++++#+Replicate+original+palatte
++++if+palette:
++++++++final.putpalette(palette)

+++++#+Cemter+paste+resized+image+to+final+canvas
++++final.paste(resized,+position)

++++#+Save+final+image+to+destination+directory
++++final.show()

++++#final.save("{}\\{}.{}".format(destination_path,+filename,+extension))

++++break|code-block|syntax|javascript|1215472|entityMap^0|0|0|9|C|M|5|11|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]|$F|X|G|Y|H|I]|$F|Z|G|10|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|11|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|12|8|@]|9|@]|A|$O|P]]|$1|Q|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|R|$]]

This code will enlarge a smaller image, preserving aspect ratio, then center it on a standard sized canvas. Also preserves transparency, or defaults to gray background.
Tested with P mode PNG files.
Coded debug <code>final.show()</code> and <code>break</code> for testing. Remove lines and hashtag on <code>final.save(...)</code> to loop and save.
Could parameterize canvas ratio and improve flexibility, but it served my purpose.
<pre class="lang-py prettyprint-override"><code>&quot;&quot;&quot;
Resize ... and reconfigures. images in a specified directory

Use case: Images of varying size, need to be enlarged to exaxtly 1200 x 1200
&quot;&quot;&quot;
import os
import glob

from PIL import Image

# Source directory plus Glob file reference (Windows)
source_path = os.path.join('C:', os.sep, 'path', 'to', 'source', '*.png')

# List of UNC Image File paths
images = glob.glob(source_path)

# Destination directory of modified image (Windows)
destination_path = os.path.join('C:', os.sep, 'path', 'to', 'destination')

for image in images:
 
 original = Image.open(image)

 # Retain original attributes (ancillary chunks)
 info = original.info
 
 # Retain original mode
 mode = original.mode

 # Retain original palette
 if original.palette is not None:
 palette = original.palette.getdata()[1]
 else:
 palette = False

 # Match original aspect ratio
 dimensions = original.getbbox()

 # Identify destination image background color
 if 'transparency' in info.keys():
 background = original.info['transparency']
 else:
 # Image does not have transparency set
 print(image)
 background = (64)

 # Get base filename and extension for destination
 filename, extension = os.path.basename(image).split('.')
 
 # Calculate matched aspect ratio
 if dimensions[2] &gt; dimensions[3]:
 width = int(1200)
 modifier = width / dimensions[2]
 length = int(dimensions[3] * modifier)
 elif dimensions[3] &gt; dimensions[2]:
 length = int(1200)
 modifier = length / dimensions[3]
 width = int(dimensions[2] * modifier)
 else:
 width, length = (1200, 1200)
 
 size = (width, length)

 # Set desired final image size
 canvas = (1200, 1200)
 
 # Calculate center position
 position = (
 int((1200 - width)/2),
 int((1200 - length)/2),
 int((1200 - width)/2) + width,
 int((1200 - length)/2) + length
 )

 # Enlarge original image proportionally
 resized = original.resize(size, Image.LANCZOS)

 # Then create sized canvas
 final = Image.new(mode, canvas, background)

 # Replicate original properties
 final.info = info

 # Replicate original palatte
 if palette:
 final.putpalette(palette)

 # Cemter paste resized image to final canvas
 final.paste(resized, position)

 # Save final image to destination directory
 final.show()

 #final.save(&quot;{}\\{}.{}&quot;.format(destination_path, filename, extension))

 break
</code></pre>

I am probably looking for the wrong thing in the handbook, but I am looking to take an image object and expand it without resizing (stretching/squishing) the original image. 

Toy example: imagine a blue rectangle, 200 x 100, then I perform some operation and I have a new image object, 400 x 300, consisting of a white background upon which a 200 x 100 blue rectangle rests. Bonus if I can control in which direction this expands, or the new background color, etc.

Essentially, I have an image to which I will be adding iteratively, and I do not know what size it will be at the outset. 

I suppose it would be possible for me to grab the original object, make a new, slightly larger object, paste the original on there, draw a little more, then repeat. It seems like it might be computationally expensive. However, I thought there would be a function for this, as I assume it is a common operation. Perhaps I assumed wrong.

In Python, Python Image Library 1.1.6, how can I expand the canvas without resizing?

Windows

我可能在手册中寻找了错误的东西，但我正在寻找一个图像对象并扩展它，而不是调整(拉伸/挤压)原始图像的大小。玩具示例:想象一个蓝色矩形，200x100，然后我执行一些操作，我有一个新的图像对象，400x300，由一个白色背景组成，上面有一个200x100蓝色矩形。如果我可以控制这个扩展的方向，或者新的背景颜色等，那就是奖...

问在Python，Python Image Library 1.1.6中，如何在不调整大小的情况下扩展画布？
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