app.py

import gradio as gr
import torch
from torchvision import transforms
from PIL import Image

# Path to your exported TorchScript models (.pt)
model_paths = {
    "All colors": "unet_generator.pt",
    "20 colors only": "20color_generator.pt"
}

# Check if a GPU is available
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")

# Image transformations (resize and convert to tensor)
transform = transforms.Compose([
    transforms.Resize((512, 512)),
    transforms.ToTensor(),
])

# Function to load the selected model
def load_model(path):
    model = torch.jit.load(path, map_location=device)
    model.eval()
    return model

# Main colorization function
def colorize(image, selected_model):
    """
    Converts the input image to grayscale, displays it,
    and generates the colorized version using the selected model.
    """
    # Convert to grayscale
    gray = image.convert("L")

    # Preprocess for model input
    gray_tensor = transform(gray).unsqueeze(0).to(device)

    # Load the selected model
    model = load_model(model_paths[selected_model])

    # Generate the colorized image
    with torch.no_grad():
        output = model(gray_tensor)

    # Process output and convert to PIL image
    output = output.squeeze(0).permute(1, 2, 0).clamp(0, 1).cpu().numpy()
    output_image = Image.fromarray((output * 255).astype('uint8'))

    return gray, output_image  # Return grayscale and colorized images

# Create Gradio interface
gr.Interface(
    fn=colorize,
    inputs=[
        gr.Image(type="pil", label="Input Image"),
        gr.Radio(choices=["All colors", "20 colors only"], label="Model")
    ],
    outputs=[
        gr.Image(type="pil", label="Grayscale Image"),
        gr.Image(type="pil", label="Colorized Image")
    ],
    title="Image Colorization",
    description=(
        "Upload a color image and choose a model to see it colorized from a grayscale version. "
        "The system first converts the input image to black and white, then uses a trained deep learning model "
        "to generate a colorized version. You can experiment with two models: one trained on a full color palette "
        "and another limited to just 20 colors."
    )
).launch()