如何调整图像的削减它在Python多余的面积？ [英] How to resize an image an cut the excess area of it in Python?

问题描述

我有一个包含图像的BASE64 code的字符串。我需要调整此图片591x608px，但我不希望它被变形，如果有不同的比例。

I have a string which contains the base64 code of an image. I need to resize this image to 591x608px, but I don't want it to be deformed if it has a different scale.

我不知道这是不是最好的方式（请纠正我，如果有一个更好的），但我想通过PIL库591x608px的矩形添加到图像。

I don't know if this is the best way (please, correct me if there is a better one), but I'm trying to add a rectangle of 591x608px to the image through the PIL library.

我试图用一个图像文件要做到这一点，它的工作，所以我试图重复这个过程用一个base64字符串，而不是文件的名称。但我并没有达到我的目的。

I tried to do this with an image file and it worked, so I was trying to repeat the process with a base64 string instead of the name of the file. But I didn't achieve my purpose.

from cStringIO import StringIO
from PIL import Image, ImageOps, ImageDraw

size = (591, 608)
mask = Image.new('L', size, 0)
draw = ImageDraw.Draw(mask)
draw.rectangle((0, 0) + size, fill=255)

# From base64 to PIL
image_string = StringIO(my_image.decode('base64'))
im = Image.open(image_string)
output = ImageOps.fit(im, mask.size, centering=(0.5, 0.5))
output.putalpha(mask)

# From PIL to base64?
output = base64.b64encode(output)

这是我的许多失败的尝试之一。它给了我一个错误：

This is one of my many failed attempts. It gives me an error:

output = base64.b64encode(output)
TypeError: must be string or buffer, not instance

谁能帮我，好吗？

Can anyone help me, please?

推荐答案

最后，我找到了解决办法。

Finally, I found a solution.

这实际上不是增加一个透明区域（所以我会编辑问题的标题），但它调整图像到指定的规模切割图像的超出部分，如果需要的话：

This isn't actually adding a transparent area (so I'll edit the title of the question), but it's resizing the image to the specified scale cutting the excess part of the image if necessary:

from cStringIO import StringIO
from PIL import Image, ImageOps, ImageDraw

size = (591, 608)
mask = Image.new('L', size, 0)
draw = ImageDraw.Draw(mask)
draw.rectangle((0, 0) + size, fill=255)

# From base64 to PIL
image_string = StringIO(my_image.decode('base64'))
im = Image.open(image_string)
output = ImageOps.fit(im, mask.size, centering=(0.5, 0.5))
output.putalpha(mask)

# From PIL to base64
output2 = StringIO()
output.save(output2, format='PNG')
im_data = output2.getvalue()
im_data = im_data.encode('base64')
# data_url = 'data:image/png;base64,' + im_data.encode('base64')

请注意，如果您打印的 im_data 的，你会看到奇怪的符号（在我的情况，我把这个字符串到一个URL和工程）。如果你想看到的 im_data 的无符号怪异，取消的最后一行。

Note that if you print im_data, you'll see weird symbols (in my case, I send this string to an URL and works). If you want to see the im_data without weird symbols, uncomment the last line.

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