裁剪时将图像类型信息保留在PIL中 [英] Preserving image type info in PIL when cropping

问题描述

我正在使用Etienne的从此处对Python的PIL进行的出色修改.我需要的正是修改的内容-使用与原始量化表相同的量化表保存JPEG文件.通过这种修改来完成它似乎很不错，我目前正在通过使用C语言的杂烩来实现.

I am using the excellent modification to Python's PIL by Etienne from here. What I need is exactly what the modification does - to save a JPEG file using the same quantization tables as the original. Doing it through that modification seems elegant, I'm currently achieving that by using a hodgepodge of C code.

我的问题是我在PIL中获得了一个JPEG文件对象，但是在进行任何修改后，它变成了某种其他类型的对象.我想要的是拍摄图像，裁剪并保存在相同的量化表中.

My problem is that I get a JPEG file object in PIL, but after any modification it becomes an object of some other type. What I want is to take the image, crop it and save it with the same quantization table.

我尝试:

img = Image.open("someimage.jpg")
width, height = img.size
crop = img.crop((8, 0, width, height))
img = img.resize((width - 8, height))
img.paste(crop, (0,0))
img.save("crop.jpg", quality='keep')

img对象首先是一个PIL.JpegImagePlugin.JpegImageFile，但是在调整大小/粘贴操作之后，它只是一个Image.因此，由于它不再是JPEG，因此我不能使用quality ='keep'.我如上所述尝试了裁剪和粘贴，还尝试了其他几种方法，但是似乎没有任何方法可以保留JpegImageFile对象.

The img object is first a PIL.JpegImagePlugin.JpegImageFile but becomes just an Image after the resize/paste operation. So consequently I can't use quality='keep' as it's no longer a JPEG. I've tried cropping and pasting as above, I tried a few other ways but nothing seems to preserve the JpegImageFile object.

推荐答案

如果您使用的是我想您是艾蒂安(Etienne)的叉子，那么您应该可以执行以下操作:

If you are using this fork by Etienne, which I think you are, then you should be able to do something like this:

img = Image.open("someimage.jpg")
qt = img.quantization
# qt is now a dictionary of arrays which is your quantization table.

width, height = img.size
crop = img.crop((8, 0, width, height))
img = img.resize((width - 8, height))
img.paste(crop, (0,0))

# pass qt in as you save your jpeg
img.save("crop.jpg",  qtables = qt)

有关更多信息，请参见此文档由Etienne

See this documentation by Etienne for more info.

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