diff --git a/genicon.py b/genicon.py
new file mode 100644
index 0000000..0e328c2
--- /dev/null
+++ b/genicon.py
@@ -0,0 +1,179 @@
+#!/usr/bin/env python3
+
+## requires poppler and pillow: pip3 install pillow
+## run as
+## -  python genicon.py '$\lambda$'
+## will produce favicon.png and favicon.ico
+
+import argparse
+import subprocess
+import tempfile
+from pathlib import Path
+
+from PIL import Image
+
+
+LATEX_TEMPLATE = r"""
+\documentclass[border=2pt]{standalone}
+\usepackage{amsmath}
+\usepackage{amssymb}
+
+\begin{document}
+%s
+\end{document}
+"""
+
+
+def run(command, cwd=None):
+    subprocess.run(
+        command,
+        cwd=cwd,
+        check=True,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+    )
+
+
+def render_favicon(
+    latex=r"$\mathcal{F}$",
+    png_path="favicon.png",
+    ico_path="favicon.ico",
+    png_size=128,
+    padding=12,
+):
+    png_path = Path(png_path)
+    ico_path = Path(ico_path)
+
+    with tempfile.TemporaryDirectory() as tmp:
+        tmp = Path(tmp)
+
+        tex_file = tmp / "favicon.tex"
+        tex_file.write_text(LATEX_TEMPLATE % latex, encoding="utf-8")
+
+        # 1. LaTeX -> tightly cropped PDF via standalone
+        run(
+            [
+                "pdflatex",
+                "-interaction=nonstopmode",
+                "-halt-on-error",
+                "favicon.tex",
+            ],
+            cwd=tmp,
+        )
+
+        pdf_file = tmp / "favicon.pdf"
+
+        # 2. PDF -> high-resolution PNG
+        raw_png_prefix = tmp / "render"
+
+        run(
+            [
+                "pdftocairo",
+                "-png",
+                "-singlefile",
+                "-r",
+                "600",
+                str(pdf_file),
+                str(raw_png_prefix),
+            ]
+        )
+
+        raw_png = tmp / "render.png"
+
+        # 3. Composite onto a pure white background
+        image = Image.open(raw_png).convert("RGBA")
+
+        white = Image.new("RGBA", image.size, (255, 255, 255, 255))
+        white.alpha_composite(image)
+        image = white.convert("RGB")
+
+        # 4. Scale while preserving aspect ratio
+        inner_size = png_size - 2 * padding
+
+        image.thumbnail(
+            (inner_size, inner_size),
+            Image.Resampling.LANCZOS,
+        )
+
+        canvas = Image.new(
+            "RGB",
+            (png_size, png_size),
+            "white",
+        )
+
+        x = (png_size - image.width) // 2
+        y = (png_size - image.height) // 2
+
+        canvas.paste(image, (x, y))
+
+        # 5. Save PNG
+        canvas.save(
+            png_path,
+            "PNG",
+            optimize=True,
+        )
+
+        # 6. Save ICO containing common favicon resolutions
+        canvas.save(
+            ico_path,
+            format="ICO",
+            sizes=[
+                (16, 16),
+                (32, 32),
+                (48, 48),
+                (64, 64),
+                (128, 128),
+            ],
+        )
+
+    print(f"Created {png_path}")
+    print(f"Created {ico_path}")
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        description="Render LaTeX into favicon PNG/ICO files."
+    )
+
+    parser.add_argument(
+        "latex",
+        nargs="?",
+        default=r"$\mathcal{F}$",
+        help=r'LaTeX to render, e.g. "$\mathcal{F}$"',
+    )
+
+    parser.add_argument(
+        "--png",
+        default="favicon.png",
+        help="Output PNG filename",
+    )
+
+    parser.add_argument(
+        "--ico",
+        default="favicon.ico",
+        help="Output ICO filename",
+    )
+
+    parser.add_argument(
+        "--size",
+        type=int,
+        default=128,
+        help="PNG canvas size in pixels",
+    )
+
+    parser.add_argument(
+        "--padding",
+        type=int,
+        default=12,
+        help="Padding around the rendered symbol",
+    )
+
+    args = parser.parse_args()
+
+    render_favicon(
+        latex=args.latex,
+        png_path=args.png,
+        ico_path=args.ico,
+        png_size=args.size,
+        padding=args.padding,
+    )