app.py

import gradio as gr
import numpy as np
import nrrd
import matplotlib.pyplot as plt
import io
from PIL import Image

# Set Matplotlib to use the 'Agg' backend
plt.switch_backend('Agg')

def load_nrrd(file_path):
    data, _ = nrrd.read(file_path.name)
    num_slices = data.shape[2]
    return data, num_slices

def visualize_slice(file_path, slice_index):
    data, num_slices = load_nrrd(file_path)
    
    # Ensure the slice index is within the range of available slices
    slice_index = min(max(0, slice_index), num_slices - 1)
    
    slice_image = data[:, :, slice_index]

    # Plot the slice
    fig, ax = plt.subplots()
    ax.imshow(slice_image, cmap='gray')
    plt.axis('off')
    
    # Convert matplotlib figure to PIL Image
    buf = io.BytesIO()
    fig.savefig(buf, format='png')
    plt.close(fig)
    buf.seek(0)
    pil_img = Image.open(buf)
    
    return pil_img

def update_slider(file_path):
    _, num_slices = load_nrrd(file_path)
    return gr.update(maximum=num_slices-1, value=0)

with gr.Blocks() as app:
    gr.Markdown("## NRRD Slice Visualizer")
    gr.Markdown("Upload an NRRD file and use the slider to select and visualize slices.")
    
    file_input = gr.File(label="Upload NRRD File")
    slider = gr.Slider(minimum=0, maximum=1, step=1, value=0, label="Slice Selector")
    image_output = gr.Image(type="pil", label="Selected Slice")
    
    file_input.change(fn=update_slider, inputs=file_input, outputs=slider)
    file_input.change(fn=visualize_slice, inputs=[file_input, slider], outputs=image_output)
    slider.change(fn=visualize_slice, inputs=[file_input, slider], outputs=image_output)

app.launch()