negative_image.py

from PIL import ImageOps, Image

from invokeai.invocation_api import (
    BaseInvocation,
    InputField,
    invocation,
    InvocationContext,
    ImageField,
    ImageOutput
)

@invocation(
    "negative_image",
    title="Negative Image",
    tags=["image", "Negative"],
    category="image",
    version="1.1.0",
)
class NegativeImageInvocation(BaseInvocation):
    """Create negative image from image"""
    image: ImageField = InputField(default=None, description="Input image")

    def invoke(self, context: InvocationContext) -> ImageOutput:
        image = context.images.get_pil(self.image.image_name).convert("RGBA")
        r, g, b, a = image.split()
        rgb_image = Image.merge("RGB", (r, g, b))
        inverted_rgb = ImageOps.invert(rgb_image)
        inverted_image = Image.merge("RGBA", (*inverted_rgb.split(), a))
        image_dto = context.images.save(image=inverted_image)
        return ImageOutput.build(image_dto)