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python PIL对YCbCr的支持

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1 回答
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提问于 2025-04-16 18:04

我在我的Ubuntu 11.04上，尝试创建一个YCbCr模式的PIL图像，结果连新安装的Python/PIL都崩溃了。

wim@wim-ubuntu:~$ python
Python 2.7.1+ (r271:86832, Apr 11 2011, 18:13:53) 
[GCC 4.5.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import Image
>>> Image.VERSION
'1.1.7'
>>> Image.new('YCbCr', (640,480))
*** buffer overflow detected ***: python terminated
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(__fortify_fail+0x37)[0x7f4a35e4a1d7]
/lib/x86_64-linux-gnu/libc.so.6(+0xfd0f0)[0x7f4a35e490f0]
/usr/local/lib/python2.7/dist-packages/PIL/_imaging.so(ImagingNewPrologueSubtype+0x97)[0x7f4a34bfb257]
/usr/local/lib/python2.7/dist-packages/PIL/_imaging.so(ImagingNewBlock+0xb)[0x7f4a34bfb78b]
/usr/local/lib/python2.7/dist-packages/PIL/_imaging.so(ImagingNew+0x4c)[0x7f4a34bfb86c]
/usr/local/lib/python2.7/dist-packages/PIL/_imaging.so(+0xfd22)[0x7f4a34bddd22]
python(PyEval_EvalFrameEx+0x361)[0x4965f1]
python(PyEval_EvalCodeEx+0x145)[0x49d325]
python(PyEval_EvalFrameEx+0x802)[0x496a92]
python(PyEval_EvalCodeEx+0x145)[0x49d325]
python(PyEval_EvalCode+0x32)[0x4ecb02]
python[0x4fdc74]
python(PyRun_InteractiveOneFlags+0x1e2)[0x42cd9e]
python(PyRun_InteractiveLoopFlags+0xc0)[0x42cebd]
python(PyRun_AnyFileExFlags+0x39)[0x42d2e1]
python(Py_Main+0xac9)[0x418c9e]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xff)[0x7f4a35d6aeff]
python[0x4c62b1]
======= Memory map: ========
00400000-0062f000 r-xp 00000000 08:21 1049585                            /usr/bin/python2.7
0082e000-0082f000 r--p 0022e000 08:21 1049585                            /usr/bin/python2.7
0082f000-00897000 rw-p 0022f000 08:21 1049585                            /usr/bin/python2.7
00897000-008a9000 rw-p 00000000 00:00 0 
01f0a000-021a1000 rw-p 00000000 00:00 0                                  [heap]
7f4a34794000-7f4a347a9000 r-xp 00000000 08:21 659235                     /lib/x86_64-linux-gnu/libgcc_s.so.1
7f4a347a9000-7f4a349a8000 ---p 00015000 08:21 659235                     /lib/x86_64-linux-gnu/libgcc_s.so.1
7f4a349a8000-7f4a349a9000 r--p 00014000 08:21 659235                     /lib/x86_64-linux-gnu/libgcc_s.so.1
7f4a349a9000-7f4a349aa000 rw-p 00015000 08:21 659235                     /lib/x86_64-linux-gnu/libgcc_s.so.1
7f4a349aa000-7f4a349cd000 r-xp 00000000 08:21 1057568                    /usr/lib/x86_64-linux-gnu/libjpeg.so.62.0.0
7f4a349cd000-7f4a34bcc000 ---p 00023000 08:21 1057568                    /usr/lib/x86_64-linux-gnu/libjpeg.so.62.0.0
7f4a34bcc000-7f4a34bcd000 r--p 00022000 08:21 1057568                    /usr/lib/x86_64-linux-gnu/libjpeg.so.62.0.0
7f4a34bcd000-7f4a34bce000 rw-p 00023000 08:21 1057568                    /usr/lib/x86_64-linux-gnu/libjpeg.so.62.0.0
7f4a34bce000-7f4a34c0b000 r-xp 00000000 08:21 1312337                    /usr/local/lib/python2.7/dist-packages/PIL/_imaging.so
7f4a34c0b000-7f4a34e0b000 ---p 0003d000 08:21 1312337                    /usr/local/lib/python2.7/dist-packages/PIL/_imaging.so
7f4a34e0b000-7f4a34e0e000 r--p 0003d000 08:21 1312337                    /usr/local/lib/python2.7/dist-packages/PIL/_imaging.so
7f4a34e0e000-7f4a34e11000 rw-p 00040000 08:21 1312337                    /usr/local/lib/python2.7/dist-packages/PIL/_imaging.so
7f4a34e11000-7f4a34e30000 r-xp 00000000 08:21 1316665                    /usr/lib/python2.7/lib-dynload/_ctypes.so
7f4a34e30000-7f4a3502f000 ---p 0001f000 08:21 1316665                    /usr/lib/python2.7/lib-dynload/_ctypes.so
7f4a3502f000-7f4a35030000 r--p 0001e000 08:21 1316665                    /usr/lib/python2.7/lib-dynload/_ctypes.so
7f4a35030000-7f4a35034000 rw-p 0001f000 08:21 1316665                    /usr/lib/python2.7/lib-dynload/_ctypes.so
7f4a35034000-7f4a35035000 rw-p 00000000 00:00 0 
7f4a35035000-7f4a35075000 r-xp 00000000 08:21 655419                     /lib/libncurses.so.5.7
7f4a35075000-7f4a35274000 ---p 00040000 08:21 655419                     /lib/libncurses.so.5.7
7f4a35274000-7f4a35278000 r--p 0003f000 08:21 655419                     /lib/libncurses.so.5.7
7f4a35278000-7f4a35279000 rw-p 00043000 08:21 655419                     /lib/libncurses.so.5.7
7f4a35279000-7f4a352b2000 r-xp 00000000 08:21 655450                     /lib/libreadline.so.6.2
7f4a352b2000-7f4a354b2000 ---p 00039000 08:21 655450                     /lib/libreadline.so.6.2
7f4a354b2000-7f4a354b4000 r--p 00039000 08:21 655450                     /lib/libreadline.so.6.2
7f4a354b4000-7f4a354ba000 rw-p 0003b000 08:21 655450                     /lib/libreadline.so.6.2
7f4a354ba000-7f4a354bb000 rw-p 00000000 00:00 0 
7f4a354bb000-7f4a354c0000 r-xp 00000000 08:21 1316693                    /usr/lib/python2.7/lib-dynload/readline.so
7f4a354c0000-7f4a356bf000 ---p 00005000 08:21 1316693                    /usr/lib/python2.7/lib-dynload/readline.so
7f4a356bf000-7f4a356c0000 r--p 00004000 08:21 1316693                    /usr/lib/python2.7/lib-dynload/readline.so
7f4a356c0000-7f4a356c2000 rw-p 00005000 08:21 1316693                    /usr/lib/python2.7/lib-dynload/readline.so
7f4a356c2000-7f4a35d4c000 r--p 00000000 08:21 1055991                    /usr/lib/locale/locale-archive
7f4a35d4c000-7f4a35ed6000 r-xp 00000000 08:21 659207                     /lib/x86_64-linux-gnu/libc-2.13.so
7f4a35ed6000-7f4a360d5000 ---p 0018a000 08:21 659207                     /lib/x86_64-linux-gnu/libc-2.13.so
7f4a360d5000-7f4a360d9000 r--p 00189000 08:21 659207                     /lib/x86_64-linux-gnu/libc-2.13.so
7f4a360d9000-7f4a360da000 rw-p 0018d000 08:21 659207                     /lib/x86_64-linux-gnu/libc-2.13.so
7f4a360da000-7f4a360e0000 rw-p 00000000 00:00 0 
7f4a360e0000-7f4a36164000 r-xp 00000000 08:21 659244                     /lib/x86_64-linux-gnu/libm-2.13.so
7f4a36164000-7f4a36363000 ---p 00084000 08:21 659244                     /lib/x86_64-linux-gnu/libm-2.13.so
7f4a36363000-7f4a36364000 r--p 00083000 08:21 659244                     /lib/x86_64-linux-gnu/libm-2.13.so
7f4a36364000-7f4a36365000 rw-p 00084000 08:21 659244                     /lib/x86_64-linux-gnu/libm-2.13.so
7f4a36365000-7f4a3637c000 r-xp 00000000 08:21 659290                     /lib/x86_64-linux-gnu/libz.so.1.2.3.4
7f4a3637c000-7f4a3657b000 ---p 00017000 08:21 659290                     /lib/x86_64-linux-gnu/libz.so.1.2.3.4
7f4a3657b000-7f4a3657c000 r--p 00016000 08:21 659290                     /lib/x86_64-linux-gnu/libz.so.1.2.3.4
7f4a3657c000-7f4a3657d000 rw-p 00017000 08:21 659290                     /lib/x86_64-linux-gnu/libz.so.1.2.3.4
7f4a3657d000-7f4a366e3000 r-xp 00000000 08:21 655398                     /lib/libcrypto.so.0.9.8
7f4a366e3000-7f4a368e3000 ---p 00166000 08:21 655398                     /lib/libcrypto.so.0.9.8
7f4a368e3000-7f4a368f0000 r--p 00166000 08:21 655398                     /lib/libcrypto.so.0.9.8
7f4a368f0000-7f4a36909000 rw-p 00173000 08:21 655398                     /lib/libcrypto.so.0.9.8
7f4a36909000-7f4a3690c000 rw-p 00000000 00:00 0 
7f4a3690c000-7f4a36958000 r-xp 00000000 08:21 655454                     /lib/libssl.so.0.9.8Aborted
wim@wim-ubuntu:~$

我试过了

find /usr -name Image.py | xargs grep -n YCbCr

并且发现我认为是问题所在的代码行

216:    "YCbCr": ('|u1', 4),

YCbCr图像应该是3个通道，而不是4个。我把这个改成了3，并删除了.pyc文件，但当代码进入C语言部分（core.fill with mode='YCbCr'）时，还是崩溃了。于是我想，也许这个错误在构建过程中混进来了，我在包管理器中标记了PIL进行完全删除，下载了源代码和依赖项，把那个4改成3，经过一番路径调整后又成功构建了PIL，所有自测都通过了，然后安装了。不幸的是，还是崩溃。现在我不知道该怎么办了——我需要在PIL中支持YCbCr色彩空间，但无法修复这个错误。

补充：也许这可以提供更多线索，我发现虽然Image.new('YCbCr', (640,480))在10.10中没有崩溃，但使用numpy.asarray(Image.new('YCbCr', (640,480)))时却会引发段错误。这一切都像是numpy和/或PIL的某个C扩展中的内存问题，或者是它们之间的沟通方式出了问题。

内存管理 ubuntu numpy 图像处理 PIL 色彩空间 c语言扩展 ycbr

1 个回答

6

经过追踪源代码，发现问题出在 strcpy() 函数，具体位置在 libImaging/Storage.c:186，导致了缓冲区溢出。进一步查看代码，我发现 im->mode 的大小不够，无法容纳 "YCbCr" 这个字符串。

要解决这个问题，只需将 libImaging/Imaging.h:78 中的 char mode[4+1]; 改为 char mode[4+2];char mode[6+1];，然后重新编译 PIL。

关于 numpy.asarray，根据 另一篇帖子，我认为这也是 PIL 的问题，你在 Image.py 上的修复应该能解决这个问题。

编辑：之前为 Fedora 提交了一个补丁，建议将其改为 char mode[6+1];，这样缓冲区就足够大，可以容纳 "RGB;32"。

题外话：如果 Linus 看到了这个，他肯定不会接受我的修复，因为这太神奇了……

回答于 2025-04-16 由 Python大师
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