src/streamlit_app.py

import streamlit as st
import cv2
import numpy as np
from PIL import Image

st.title('Image to Sketch')
file = st.file_uploader('Upload an portrait image', type=['jpg', 'png', 'jpeg'])
if file:
    img = Image.open(file).convert('RGB')
    img_np = np.array(img)
    img_bw = cv2.cvtColor(img_np, cv2.COLOR_RGB2BGR)
    gray = cv2.cvtColor(img_bw, cv2.COLOR_RGB2GRAY)
    inverted = 255 - gray
    blurred = cv2.GaussianBlur(inverted, (21, 21), 0)

    def dodge(front, back):
        return cv2.divide(front, 255 - back, scale=255)
    
    sketch = dodge(gray, blurred)

    st.subheader('Original vs Sketch')
    col1, col2 = st.columns(2)
    with col1:
        st.image(img, caption='Original', use_column_width=True)
    with col2:
        st.image(sketch, caption='Sketch')