app.py

import streamlit as st
st.set_page_config(page_title="Blur App", page_icon=":camera_with_flash:")

from PIL import Image, ImageFilter
import torch
from torchvision import transforms
from transformers import AutoModelForImageSegmentation, DepthProImageProcessorFast, DepthProForDepthEstimation
import numpy as np

# pointless since no GPU access
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")


st.title("Blur an image!")
st.subheader("Upload your image and choose a blur style")
st.text("A background blur uses segmentation to completely blur all background objects.\n A lens blur applies gradual blur using depth estimation.")
st.divider()

st.warning("**Note**: The lens blur option takes a long time to process (>5min) since this space isn't linked to a GPU.")

@st.cache_resource(show_spinner="Pushing pixels...")
def load_gblur_model():
    birefnet = AutoModelForImageSegmentation.from_pretrained('ZhengPeng7/BiRefNet', trust_remote_code=True)
    birefnet.to(device)
    birefnet.eval()
    return birefnet

@st.cache_resource(show_spinner="Running with scissors...")
def load_lblur_model():
    image_processor = DepthProImageProcessorFast.from_pretrained("apple/DepthPro-hf")
    model = DepthProForDepthEstimation.from_pretrained("apple/DepthPro-hf").to(device)
    return model, image_processor

gblur_model = load_gblur_model()
lblur_model, lblur_img_proc = load_lblur_model()

def gaussian_blur(image, blur_str):   
    # Image transform
    image_size = (512, 512)
    transform_image = transforms.Compose([
        transforms.Resize(image_size),
        transforms.ToTensor(),
        transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225])
    ])
    
    # Prediction
    input_image = transform_image(image).unsqueeze(0).to(device)
    with torch.no_grad():
        preds = gblur_model(input_image)[-1].sigmoid().cpu()
    pred = preds[0].squeeze()
    pred_pil = transforms.ToPILImage()(pred)
    mask = np.array(pred_pil.resize(image.size))

    # Blurring
    blur = np.array(image.filter(ImageFilter.GaussianBlur(radius=blur_str)))
    mask = np.expand_dims(mask, axis=2)
    output_image = np.where(mask, np.array(image), blur)
    
    return Image.fromarray(output_image)

def lens_blur(image, blur_str):
    # Process image
    inputs = lblur_img_proc(images=image, return_tensors="pt").to(device)

    # Perform forward pass
    with torch.no_grad():
        outputs = lblur_model(**inputs)
    
    post_processed_output = lblur_img_proc.post_process_depth_estimation(
        outputs, target_sizes=[(image.height, image.width)],
    )

    # Get depth map
    depth = post_processed_output[0]["predicted_depth"]
    depth = (depth - depth.min()) / (depth.max() - depth.min())
    depth = depth * 255.
    depth = depth.detach().cpu().numpy()

    # Normalize map
    depth = depth / 255.0
    
    # No of discrete blurs and max blur intensity
    num_levels = 15
    max_radius = blur_str
    
    # Pre-compute all blur images
    blurred_images = []
    for i in range(num_levels):
        radius = (i / (num_levels - 1)) * max_radius
        if radius < 0.1:
            blurred_images.append(np.array(image))
        else:
            blurred = np.array(image.filter(ImageFilter.GaussianBlur(radius)))
            blurred_images.append(blurred)
    blurred_stack = np.stack(blurred_images, axis=0)
    
    # Blend together the images using 
    # Bilinear Interpolation of depth levels
    h, w = depth.shape
    y_coords, x_coords = np.indices((h, w))
    
    depth_levels = depth * (num_levels - 1)
    low_levels = np.floor(depth_levels).astype(int)
    high_levels = np.clip(low_levels + 1, 0, num_levels - 1)
    alpha = depth_levels - low_levels
    
    pixel_low = blurred_stack[low_levels, y_coords, x_coords, :].astype(np.float32)
    pixel_high = blurred_stack[high_levels, y_coords, x_coords, :].astype(np.float32)
    
    output = (1 - alpha)[..., np.newaxis] * pixel_low + alpha[..., np.newaxis] * pixel_high
    
    # Final blurred image
    output_img = Image.fromarray(np.clip(output, 0, 255).astype(np.uint8))
    return output_img

left, right = st.columns(2)
with left:
    st.header("Upload your image")
    up_img = st.file_uploader("Upload image", type=["jpg", "jpeg", "png", "dng", "tiff"])

with right:
    st.header("Set blur settings.")
    st.text("Choose a blur style, set the blur strength, and hit 'Apply'!")
    with st.form("Blur_form"):
        options = ["Background", "Lens"]
        selection = st.radio(
            "Choose a blur type:", 
            options, index=None,
            captions=[
                "Use segmentation", 
                "Use depth estimation"], 
            horizontal=True
        )
        blur_level = st.select_slider("Blur Strength", options=["very low","low","medium","high","very high"])
        submitted = st.form_submit_button("Apply Blur", disabled=(up_img is None), type="primary")
st.divider()

blur_levels = {"very low":5, "low":10, "medium":15, "high":20, "very high":30}
if up_img:
    image = Image.open(up_img).convert("RGB")
    disp_left, disp_right = st.columns(2)
    with disp_left:
        og_img = image.copy()
        st.image(og_img, caption="Original Image", width=300)
    with disp_right:
        if submitted and selection in options:
            blur_str = blur_levels[blur_level]
            if selection == "Background":
                with st.spinner(f"Spinning violently around the y-axis..."):
                    result = gaussian_blur(image, blur_str)
            elif selection == "Lens":
                with st.spinner(f"One mississippi, two mississippi..."):
                    result = lens_blur(image, blur_str)
            st.image(result, "Blurred Image", width=300)
        else:
            st.write("Waiting for you to select a blur type...")