Inverting PNG Files

[Yodazon]

Hi everyone!
My goal is to invert some PNG files for an ML project I am doing. Currently I am using the ImageOps.invert module to achieve this.

I am running into an error stating "OSError: not supported for this image mode" for when I attempt this.
Earlier in the same project I utilize ImageOps.grayscale on the same images and it works like a charm. Therefore I am unsure where the issue lies.

Help is appreciated! Thanks

[bigcat88]

It will be helpful to first identify the version of Pillow and the example you are reproducing, where this error occurs.

[Yodazon]

Looks like the mode that it fails on is the RGBA image mode

[radarhere]

Thanks. I'm guessing that you would like to invert the red, green and blue channels, but keep the alpha channel the same. If so, try the following

def invertImage(imgs):
    converted = []
    for img in imgs:
        if img.mode == "RGBA":
            img_a = img.getchannel("A")
            img_rgb = img.convert("RGB")
            invert = ImageOps.invert(img_rgb)
            invert.putalpha(img_a)
        else:
            invert = ImageOps.invert(img)
        converted.append(invert)
    return converted

[Yodazon]

I tried out the cost you posted @radarhere and I am given the same final error. Full error message is as followed:

 ImageOps.invert(img)
  File "my\path\here\Python\Python311\Lib\site-packages\PIL\ImageOps.py", line 534, in invert
    return image.point(lut) if image.mode == "1" else _lut(image, lut)
                                                      ^^^^^^^^^^^^^^^^
  File "my\path\here\Python\Python311\Lib\site-packages\PIL\ImageOps.py", line 60, in _lut
    raise OSError(msg)
OSError: not supported for this image mode

[radarhere]

The error is being raised on ImageOps.invert(img), which is not in the "RGBA" part of my code - this makes me think that I've solved your RGBA problem, but there is another mode you are having trouble with as well.

Does this code print out something like "Image mode: RGBA" just before the traceback? What is that mode?

def invertImage(imgs):
    converted = []
    for img in imgs:
        if img.mode == "RGBA":
            img_a = img.getchannel("A")
            img_rgb = img.convert("RGB")
            invert = ImageOps.invert(img_rgb)
            invert.putalpha(img_a)
        else:
            try:
                invert = ImageOps.invert(img)
            except OSError as e:
                print("Image mode:", img.mode)
                raise e
        converted.append(invert)
    return converted

[radarhere]

@Yodazon is there any further help you need?

[Yodazon]

Hi there,

I ran the code in the previous comment and still had the same issue. Output is as followed:

my/path/here/ Photo.svg.png has image mode RGBA
Traceback (most recent call last):
  File "my/path/here/", line 80, in <module>
    ImageOps.invert(img)
  File "my\path\here\Python\Python311\Lib\site-packages\PIL\ImageOps.py", line 534, in invert
    return image.point(lut) if image.mode == "1" else _lut(image, lut)
                                                      ^^^^^^^^^^^^^^^^
  File "my\path\here\Python\Python311\Lib\site-packages\PIL\ImageOps.py", line 60, in _lut
    raise OSError(msg)
OSError: not supported for this image mode

[radarhere]

ImageOps.invert(img) is not a line in my last comment with code. invert = ImageOps.invert(img) is the closest line. So it doesn't look like you're running the code that I suggested.

[Yodazon]

Yes, I looked into it and you are correct! It was some of the test code from earlier. The solution you posted works! I am curious as to why it works though