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)
    return data

def visualize_slice(file_path, slice_index, view_axis):
    data = load_nrrd(file_path)
    
    # Ensure the slice index is within the range of available slices
    slice_index = min(max(0, slice_index), data.shape[view_axis] - 1)
    
    if view_axis == 0:  # Axial
        slice_image = np.rot90(data[slice_index, :, :], k=1)
    elif view_axis == 1:  # Coronal
        slice_image = np.rot90(data[:, slice_index, :], k=1)
    elif view_axis == 2:  # Sagittal
        slice_image = np.flipud(np.rot90(data[:, :, slice_index], k=1))

    # 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, view_axis):
    data = load_nrrd(file_path)
    middle_slice = data.shape[view_axis] // 2
    return gr.update(maximum=data.shape[view_axis] - 1, value=middle_slice)

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")
    view_axis_selector = gr.Radio(choices=[0, 1, 2], value=2, label="View Axis", info="0: Axial, 1: Coronal, 2: Sagittal")
    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, view_axis_selector], outputs=slider)
    file_input.change(fn=visualize_slice, inputs=[file_input, slider, view_axis_selector], outputs=image_output)
    view_axis_selector.change(fn=update_slider, inputs=[file_input, view_axis_selector], outputs=slider)
    slider.change(fn=visualize_slice, inputs=[file_input, slider, view_axis_selector], outputs=image_output)

app.launch()