python图像库无法将PNG保存为JPG

Question

我在 Mac OSX 上从源代码安装了 PIL 1.1.7。我还从 Macports 安装了所需的库。使用 python 2.6。

安装PIL后，我可以成功运行selftest.py(所有测试通过)

但是当我尝试运行以下代码时，我发现我无法将 PNG 转换为 JPG。但是，我能够将 PNG 转换为 GIF，将 PNG 转换为 PPM。我还可以阅读 JPG。

import os
import sys 
import Image

for infile in sys.argv[1:]:
    f, e = os.path.splitext(infile)
    outfile = f + ".jpg"
    print outfile
    if infile != outfile:
        try:
            Image.open(infile).save(outfile, 'jpg') #Note: gif or ppm works
        except IOError:
            print "cannot convert", infile
            if os.path.exists(outfile):
               print 'cleaning up...'
               os.remove(outfile)

** 使用堆栈跟踪更新。看起来编码器丢失了。但是我确实通过 macport 安装了 libjpeg。

清理...

Traceback (most recent call last):
  File "convert_to_jpeg.py", line 15, in <module>
    Image.open(infile).save(outfile, 'jpeg')
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/PIL/Image.py", line 1439, in save
    save_handler(self, fp, filename)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/PIL/JpegImagePlugin.py", line 471, in _save
    ImageFile._save(im, fp, [("jpeg", (0,0)+im.size, 0, rawmode)])
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/PIL/ImageFile.py", line 495, in _save
    e = Image._getencoder(im.mode, e, a, im.encoderconfig)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/PIL/Image.py", line 401, in _getencoder
    raise IOError("encoder %s not available" % encoder_name)
IOError: encoder jpeg not available

Answer 1

使用 jpeg 而不是 jpg 作为格式标识符。