app.py

import gradio as gr

import os
import torch

import numpy as np

device = torch.device('cuda') if torch.cuda.is_available() else torch.device('cpu')

from diffusers import DiffusionPipeline
import torchvision.transforms as transforms

from copy import deepcopy
from collections import OrderedDict

import requests
import json

from PIL import Image, ImageEnhance
import base64
import io

class BZHStableSignatureDemo(object):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.pipe = DiffusionPipeline.from_pretrained("stabilityai/sdxl-turbo", torch_dtype=torch.float16, variant="fp16").to("cuda")

        # load the patched VQ-VAEs
        sd1 = deepcopy(self.pipe.vae.state_dict()) # save initial state dict
        self.decoders = decoders = OrderedDict([("no watermark", sd1)])
        for name, patched_decoder_ckpt in (
                ("weak", "models/checkpoint_000.pth.50000"),
                ("medium", "models/checkpoint_000.pth.150000"),
                ("strong", "models/checkpoint_000.pth.500000"),
                ("extreme", "models/checkpoint_000.pth.1500000")):
            sd2 = torch.load(patched_decoder_ckpt)['ldm_decoder']
            msg = self.pipe.vae.load_state_dict(sd2, strict=False)
            print(f"loaded LDM decoder state_dict with message\n{msg}")
            print("you should check that the decoder keys are correctly matched")
            decoders[name] = sd2
        self.decoders = decoders

    def generate(self, mode, seed, prompt):
        generator = torch.Generator(device=device)
        if seed:
            torch.manual_seed(seed)

        # load the patched VAE decoder
        sd = self.decoders[mode]
        self.pipe.vae.load_state_dict(sd, strict=False)

        output = self.pipe(prompt, num_inference_steps=4, guidance_scale=0.0, output_type="pil")
        return output.images[0]

    @staticmethod
    def pad(img, padding, mode="edge"):
        npimg = np.asarray(img)
        nppad = ((padding[1], padding[3]), (padding[0], padding[2]), (0,0))
        npimg = np.pad(npimg, nppad, mode=mode)
        return Image.fromarray(npimg)

    def attack_detect(self, img, jpeg_compression, downscale, saturation):

        # attack
        if downscale != 1:
            size = img.size
            size = (int(size[0] / downscale), int(size[1] / downscale))
            img = img.resize(size, Image.BICUBIC)

        converter = ImageEnhance.Color(img)
        img = converter.enhance(saturation)
        
        # send to detection API and apply JPEG compression attack
        mf = io.BytesIO()
        img.save(mf, format='JPEG', quality=jpeg_compression) # includes JPEG attack
        b64 = base64.b64encode(mf.getvalue())
        data = {
            'image': b64.decode('utf8')
        }
        
        headers = {}
        api_key = os.environ.get('BZH_API_KEY', None)
        if api_key:
            headers['BZH_API_KEY'] = api_key
        response = requests.post('https://bzh.imatag.com/bzh/api/v1.0/detect',
                                 json=data, headers=headers)
        response.raise_for_status()
        data = response.json()
        pvalue = data['p-value']

        mf.seek(0)
        img0 = Image.open(mf) # reload to show JPEG attack
        #result = "resolution = %dx%d  p-value = %e" % (img.size[0], img.size[1], pvalue))
        result = "No watermark detected."
        chances = int(1 / pvalue + 1)
        if pvalue < 1e-3:
            result = "Weak watermark detected" # (< 1/%d chances of being wrong)" % chances
        if pvalue < 1e-9:
            result = "Strong watermark detected" # (< 1/%d chances of being wrong)" % chances
        return (img0, result)


def interface():
    prompt = "sailing ship in storm by Rembrandt"

    backend = BZHStableSignatureDemo()
    decoders = list(backend.decoders.keys())

    with gr.Blocks() as demo:
        gr.Markdown("""# Watermarked SDXL-Turbo demo
        This demo presents watermarking of images generated via StableDiffusion XL Turbo.
        Using the method presented in [StableSignature](https://ai.meta.com/blog/stable-signature-watermarking-generative-ai/),
        the VAE decoder of StableDiffusion is fine-tuned to produce images including a specific invisible watermark. We combined
        this method with our in-house decoder which operates in zero-bit mode for improved robustness.""")

        with gr.Row():
            inp = gr.Textbox(label="Prompt", value=prompt)
            seed = gr.Number(label="Seed", precision=0)
            mode = gr.Dropdown(choices=decoders, label="Watermark strength", value="medium")
        with gr.Row():
            btn1 = gr.Button("Generate")
        with gr.Row():
            watermarked_image = gr.ImageEditor(type="pil", width=512, height=512)
            with gr.Column():
                downscale = gr.Slider(1, 3, value=1, step=0.1, label="Downscale ratio")
                saturation = gr.Slider(0, 2, value=1, step=0.1, label="Color saturation")
                jpeg_compression = gr.Slider(value=100, step=5, label="JPEG quality")
                btn2 = gr.Button("Attack & Detect")
                with gr.Row():
                    attacked_image = gr.Image(type="pil", width=256)
                    detection_label = gr.Label(label="Detection info")
        btn1.click(fn=backend.generate, inputs=[mode, seed, inp], outputs=[watermarked_image], api_name="generate")
        btn2.click(fn=backend.attack_detect, inputs=[watermarked_image, jpeg_compression, downscale, saturation], outputs=[attacked_image, detection_label], api_name="detect")

    return demo

if __name__ == '__main__':
    demo = interface()
    demo.launch()