Question

我正在尝试调整一些图像的大小，其中大部分都是JPG。但是在一些图片中，我收到了错误：

Traceback (most recent call last):
  File "image_operation_new.py", line 168, in modifyImage
    tempImage.save(finalName);
  File "/Users/kshitiz/.virtualenvs/django_project/lib/python2.7/site-     packages/PIL/Image.py", line 1465, in save
   save_handler(self, fp, filename)
  File "/Users/kshitiz/.virtualenvs/django_project/lib/python2.7/site-   packages/PIL/JpegImagePlugin.py", line 455, in _save
    raise IOError("cannot write mode %s as JPEG" % im.mode)
IOError: cannot write mode P as JPEG

我没有改变图像类型，我正在使用枕头库。我的操作系统是Mac OS X.我该如何解决这个问题？

Answer 1

您需要将图像转换为RGB模式。

Image.open('old.jpeg').convert('RGB').save('new.jpeg')

Answer 2

这个答案很老了，但是，我想我会通过在转换之前检查模式来提出一种更好的方法：

if img.mode != 'RGB':
    img = img.convert('RGB')

这是将图像保存为JPEG格式所必需的。

Answer 3

摘要1和2：

背景
- JPG不支持alpha = transparency
- RGBA，P有alpha = transparency
  - RGBA = Red Green Blue Alpha
结果
- cannot write mode RGBA as JPEG
- cannot write mode P as JPEG
解决方案
- 在保存为JPG之前，丢弃alpha = transparency
  - 例如：将Image转换为RGB
- 然后保存到JPG
您的代码

if im.mode == "JPEG":
    im.save("xxx.jpg")
    # in most case, resulting jpg file is resized small one
elif rgba_or_p_im.mode in ["RGBA", "P"]:
    rgb_im = rgba_or_p_im.convert("RGB")
    rgb_im.save("xxx.jpg")
    # some minor case, resulting jpg file is larger one, should meet your expectation

为您做更多：

关于调整imgae文件大小，我实现了一个功能，供您参考：

from PIL import Image, ImageDraw
cfgDefaultImageResample = Image.BICUBIC # Image.LANCZOS

def resizeImage(inputImage,
                newSize,
                resample=cfgDefaultImageResample,
                outputFormat=None,
                outputImageFile=None
                ):
    """
        resize input image
        resize normally means become smaller, reduce size
    :param inputImage: image file object(fp) / filename / binary bytes
    :param newSize: (width, height)
    :param resample: PIL.Image.NEAREST, PIL.Image.BILINEAR, PIL.Image.BICUBIC, or PIL.Image.LANCZOS
        https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.thumbnail
    :param outputFormat: PNG/JPEG/BMP/GIF/TIFF/WebP/..., more refer:
        https://pillow.readthedocs.io/en/stable/handbook/image-file-formats.html
        if input image is filename with suffix, can omit this -> will infer from filename suffix
    :param outputImageFile: output image file filename
    :return:
        input image file filename: output resized image to outputImageFile
        input image binary bytes: resized image binary bytes
    """
    openableImage = None
    if isinstance(inputImage, str):
        openableImage = inputImage
    elif CommonUtils.isFileObject(inputImage):
        openableImage = inputImage
    elif isinstance(inputImage, bytes):
        inputImageLen = len(inputImage)
        openableImage = io.BytesIO(inputImage)

    if openableImage:
        imageFile = Image.open(openableImage)
    elif isinstance(inputImage, Image.Image):
        imageFile = inputImage
    # <PIL.PngImagePlugin.PngImageFile image mode=RGBA size=3543x3543 at 0x1065F7A20>
    imageFile.thumbnail(newSize, resample)
    if outputImageFile:
        # save to file
        imageFile.save(outputImageFile)
        imageFile.close()
    else:
        # save and return binary byte
        imageOutput = io.BytesIO()
        # imageFile.save(imageOutput)
        outputImageFormat = None
        if outputFormat:
            outputImageFormat = outputFormat
        elif imageFile.format:
            outputImageFormat = imageFile.format
        imageFile.save(imageOutput, outputImageFormat)
        imageFile.close()
        compressedImageBytes = imageOutput.getvalue()
        compressedImageLen = len(compressedImageBytes)
        compressRatio = float(compressedImageLen)/float(inputImageLen)
        print("%s -> %s, resize ratio: %d%%" % (inputImageLen, compressedImageLen, int(compressRatio * 100)))
        return compressedImageBytes

最新代码可在此处找到：

https://github.com/crifan/crifanLibPython/blob/master/crifanLib/crifanMultimedia.py

Answer 4

面临同样的错误，但在 SUM(IF [Timestamp] <= [createdAt] THEN 1 ELSE 0 END) 方法之后。

解决方法一样：转成RGB

quantize()

Answer 5

JPEG 不支持 alpha = 透明度所以在保存到 JPEG 之前丢弃 alpha = 透明度

如果您使用不同的格式，您可以检查扩展名并专门为 JPEG 使用隐蔽。

extension = str(imgName).split('.')[-1]

if extension == "png":
    bg_image.save(imgName, "PNG")
else:
    if bg_image.mode in ("RGBA", "P"):
        bg_image = bg_image.convert("RGB")
    bg_image.save(imgName, "JPEG")

在JPG图像上操作时，“无法将模式P写为JPEG”

5 个答案: