---
title: "How to add a blur-to-focus reveal with Claude (tested prompt and script)"
description: "The video opens as a thick blur where only the bottle's purple shape shows, then pulls into crisp focus by 1.3 seconds. Install one skill and ask Claude Code, or run the Python script we tested yourself."
url: https://www.recharm.com/effects/blur-to-focus-reveal
---

# How to add a blur-to-focus reveal with Claude

The video opens as a thick blur where only the bottle's purple shape shows, then pulls into crisp focus by 1.3 seconds.

Made by the script on this page, from our own test clip.

## Get this effect

1. ### Switch to Code in your [Claude Desktop App](https://claude.com/download)

2. ### Install the skill (once)

   ```
   Install the Recharm video effects skill: download https://recharm-growth-staging.s3.us-east-2.amazonaws.com/website/downloads/recharm-video-effects.zip and unzip it into ~/.claude/skills
   ```

3. ### Ask for the effect

   ```
   Add a blur-to-focus reveal to input.mp4
   Starting blur radius as a share of the frame width (0.05 is 27 pixels on a 540-wide video): 0.05
   Seconds the opening stays fully blurred: 0.3
   ```

## Several videos, several effects, one ask

Put your clips in the folder, mention them with @, and ask for everything at once. Claude runs one tested script after another on each clip, then joins them.

Add a blur-to-focus reveal to **@clip1.mp4**, put a sale badge on **@clip2.mp4**, give **@clip3.mp4** a VHS look, then join all three with crossfades.

## Settings you can change

Ask Claude to change any of these, or edit them at the top of the script.

| Setting | Default | What it does                                                                                |
| ------- | ------- | ------------------------------------------------------------------------------------------- |
| `BLUR`  | `0.05`  | Starting blur radius as a share of the frame width (0.05 is 27 pixels on a 540-wide video). |
| `HOLD`  | `0.3`   | Seconds the opening stays fully blurred.                                                    |
| `FOCUS` | `1.3`   | Second the picture is fully sharp.                                                          |

## Without the skill

Don’t want to install the skill? Paste this prompt into Claude Code and Claude writes the script itself.

```
Add a blur-to-focus reveal to the start of input.mp4: the first 0.3 seconds are fully blurred with a Gaussian blur of sigma 27 pixels (5% of the 540-pixel frame width) over the whole frame, then the blur eases out (sigma = 27 x (1 - p)^3, where p goes from 0 at 0.3 seconds to 1 at 1.3 seconds) so the picture is completely sharp from 1.3 seconds and untouched after that. Don't darken, fade or zoom the frame. Use Python with OpenCV (cv2.GaussianBlur) on each frame and ffmpeg to read and write the video, keep the size, frame rate (30fps, H.264 yuv420p) and audio the same, and save it as output.mp4.
```

## Run it without Claude

This is the exact script we tested. Save it as `blur-to-focus-reveal.py` and run:

```
python3 blur-to-focus-reveal.py input.mp4 output.mp4
```

```
#!/usr/bin/env python3
"""Blur-to-focus reveal: the video opens as a heavy blur and pulls into sharp focus over its first second.

Usage: python3 blur-to-focus-reveal.py input.mp4 output.mp4
Needs ffmpeg, OpenCV and numpy (pip install opencv-python-headless numpy).
"""
import json
import subprocess
import sys

import cv2
import numpy as np

BLUR = 0.05      # starting blur radius (Gaussian sigma) as a share of the frame width
HOLD = 0.3       # seconds the opening stays fully blurred
FOCUS = 1.3      # second the picture is fully sharp

def sigma(t):
    """Blur radius in pixels at time t: full until HOLD, easing out to zero at FOCUS."""
    p = min(max((t - HOLD) / (FOCUS - HOLD), 0), 1)
    return BLUR * w * (1 - p) ** 3

def probe(path):
    info = json.loads(subprocess.check_output(["ffprobe", "-v", "error", "-select_streams", "v:0", "-show_entries",
                                               "stream=width,height,r_frame_rate", "-of", "json", path]))
    s = info["streams"][0]
    num, den = s["r_frame_rate"].split("/")
    return s["width"], s["height"], s["r_frame_rate"], float(num) / float(den)

src, out = sys.argv[1:3]
w, h, rate, fps = probe(src)
reader = subprocess.Popen(["ffmpeg", "-v", "error", "-i", src, "-f", "rawvideo", "-pix_fmt", "rgb24", "-"],
                          stdout=subprocess.PIPE)
writer = subprocess.Popen(["ffmpeg", "-y", "-v", "error", "-f", "rawvideo", "-pix_fmt", "rgb24", "-s", f"{w}x{h}",
                           "-r", rate, "-i", "-", "-i", src, "-map", "0:v", "-map", "1:a?", "-c:v", "libx264",
                           "-crf", "18", "-pix_fmt", "yuv420p", "-c:a", "copy", "-shortest", out],
                          stdin=subprocess.PIPE)
i = 0
while True:
    buf = reader.stdout.read(w * h * 3)
    if len(buf) < w * h * 3:
        break
    img = np.frombuffer(buf, np.uint8).reshape(h, w, 3)
    s = sigma(i / fps)
    if s > 0.3:
        img = cv2.GaussianBlur(img, (0, 0), s, borderType=cv2.BORDER_REFLECT)
    writer.stdin.write(img.tobytes())
    i += 1
writer.stdin.close()
if reader.wait() or writer.wait():
    sys.exit("ffmpeg failed")
```

## More hook openers

- [Breaking news banner **Breaking news banner**](https://www.recharm.com/effects/breaking-news-banner)
- [Camera shake **Camera shake**](https://www.recharm.com/effects/camera-shake)
- [Color reveal **Color reveal**](https://www.recharm.com/effects/color-reveal)
- [Countdown intro **Countdown intro**](https://www.recharm.com/effects/countdown-intro)
- [Curtain reveal **Curtain reveal**](https://www.recharm.com/effects/curtain-reveal)

## Find 3x _winning ads_

Recharm cuts your ad footage into tagged, searchable clips: hooks, testimonials, product shots. Find the shots that win, add the effect with Claude, and ship 3x more ad edits.

[Start 14-day free trial](https://www.recharm.com/get-started)