app.py

import gradio as gr
import torch
from torchvision import transforms
from PIL import Image
from colorization_model import ColorizationModel  # Import your model class

# Load the trained generator model
model_path = "generator.pth"
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")

# Define model options (replace with your configuration)
class Options:
    input_nc = 1
    output_nc = 2
    ngf = 64
    netG = "unet_256"
    norm = "batch"
    no_dropout = False
    init_type = "normal"
    init_gain = 0.02
    gpu_ids = [0] if torch.cuda.is_available() else []

opt = Options()
generator = ColorizationModel(opt).netG
generator.load_state_dict(torch.load(model_path, map_location=device))
generator.eval().to(device)

# Define preprocessing and postprocessing steps
def preprocess_image(image):
    transform = transforms.Compose([
        transforms.Grayscale(num_output_channels=1),
        transforms.Resize((256, 256)),
        transforms.ToTensor(),
        transforms.Normalize(mean=[0.5], std=[0.5])
    ])
    return transform(image).unsqueeze(0).to(device)

def postprocess_image(output):
    output = output.squeeze(0).cpu().detach()
    output = torch.cat([output[0:1, :, :] * 50.0 + 50.0, output[1:, :, :] * 110.0], dim=0)
    output_image = transforms.ToPILImage()(output)
    return output_image

# Gradio interface function
def colorize(grayscale_image):
    input_tensor = preprocess_image(grayscale_image)
    with torch.no_grad():
        colorized = generator(input_tensor)
    return postprocess_image(colorized)

# Define Gradio interface
interface = gr.Interface(
    fn=colorize,
    inputs=gr.Image(type="pil", label="Grayscale Image"),
    outputs=gr.Image(type="pil", label="Colorized Image"),
    title="Pix2Pix Image Colorization",
    description="Upload a grayscale image, and the model will colorize it using Pix2Pix GAN."
)

# Launch the app
if __name__ == "__main__":
    interface.launch()