获得“不能写模式 P 为 JPEG”，同时操作 JPG 图像

You need to convert the image to RGB mode.

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

This answer is quite old, however, I thought I will put a better way to do the same by checking for the mode before doing the conversion:

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

This is required to save your image in JPEG format.

summary 1 and 2:

• backgroud
  • JPG not support alpha = transparency
  • RGBA, P has alpha = transparency
    • RGBA= Red Green Blue Alpha
• result
  • cannot write mode RGBA as JPEG
  • cannot write mode P as JPEG
• solution
  • before save to JPG, discard alpha = transparency
    • such as: convert Image to RGB
  • then save to JPG
• your code

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

• do more for you:

about resize imgae file, I have implement a function, for your refer:

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

latest code can found here:

https://github.com/crifan/crifanLibPython/blob/master/python3/crifanLib/thirdParty/crifanPillow.py

Faced with the same error but after the quantize() method.

The solution the same: convert to RGB

image.quantize(colors=256, method=2).convert('RGB')

JPEG does not support alpha = transparency So before saving to JPEG discard alpha = transparency

You can check the extension and specifically use covert for JPEG if you work with different formats.

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")