--- title: "How to add a dithering with Claude (tested prompt and script)" description: "The shot is redrawn in nothing but black and white square dots: the pale holographic backdrop becomes a sparse crosshatch grid, the glass bottle a denser one, and the dropper cap solid black. Install one skill and ask Claude Code, or run the Python script we tested yourself." url: https://www.recharm.com/effects/dithering --- # How to add a dithering with Claude The shot is redrawn in nothing but black and white square dots: the pale holographic backdrop becomes a sparse crosshatch grid, the glass bottle a denser one, and the dropper cap solid black. 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 dithering to input.mp4 Size of each dot in pixels: 3 Input brightness that becomes solid black: 90 ``` ## 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 dithering 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 | | ------- | ------- | ---------------------------------------------------------------------------------------- | | `DOT` | `3` | Size of each dot in pixels. 1 is finest, 4 or more looks more retro. | | `BLACK` | `90` | Input brightness that becomes solid black. Raise it for darker, denser dots. | | `WHITE` | `225` | Input brightness that becomes solid white. Lower it to clear dots out of the highlights. | | `INK` | `0` | Value of the dark dots (0 is black). | | `PAPER` | `255` | Value of the light dots (255 is white). | ## Without the skill Don’t want to install the skill? Paste this prompt into Claude Code and Claude writes the script itself. ``` Give input.mp4 a 1-bit ordered dithering look for its whole length. Work in grayscale at one third of the size (180x320 for a 540x960 clip, area downscale). Stretch brightness 90 to 225 to a 0-1 tone (clip anything outside), then compare each pixel's tone with an 8x8 Bayer threshold matrix tiled over the frame (thresholds (i + 0.5) / 64): above the threshold becomes pure white (255), otherwise pure black (0). Scale back up to full size with nearest neighbor so each dot is a crisp 3x3 pixel square. No grays or colors should be left in the picture. Use Python with numpy and ffmpeg, keep the size, 30fps and the audio, and save it as output.mp4. ``` ## Run it without Claude This is the exact script we tested. Save it as `dithering.py` and run: ``` python3 dithering.py input.mp4 output.mp4 ``` ``` #!/usr/bin/env python3 """Dithering: redraw the shot in pure black and white, building every gray out of a fixed grid of dots. Usage: python3 dithering.py input.mp4 output.mp4 Needs ffmpeg and numpy (pip install numpy). """ import subprocess import sys import numpy as np DOT = 3 # size of each dot in pixels (1 is finest, 4 looks more retro) BLACK = 90 # input brightness that becomes solid black WHITE = 225 # input brightness that becomes solid white INK = 0 # dark dot value (0 = black) PAPER = 255 # light dot value (255 = white) # 8x8 Bayer matrix: thresholds spread evenly over 0-1, so a tone of 30% turns on 30% of each tile's dots BAYER = np.array([[0]], np.float32) for _ in range(3): BAYER = np.block([[4 * BAYER, 4 * BAYER + 2], [4 * BAYER + 3, 4 * BAYER + 1]]) BAYER = (BAYER + 0.5) / BAYER.size src, out = sys.argv[1], sys.argv[2] w, h = map(int, subprocess.check_output(["ffprobe", "-v", "error", "-select_streams", "v:0", "-show_entries", "stream=width,height", "-of", "csv=s=x:p=0", src]).decode().strip().split("x")) sw, sh = w // DOT, h // DOT # one dot per DOT x DOT block # read the clip as grayscale at dot resolution, write it back at full size with the original audio reader = subprocess.Popen(["ffmpeg", "-v", "error", "-i", src, "-vf", f"scale={sw}:{sh}:flags=area,format=gray", "-r", "30", "-f", "rawvideo", "-"], stdout=subprocess.PIPE) writer = subprocess.Popen(["ffmpeg", "-v", "error", "-y", "-f", "rawvideo", "-pix_fmt", "gray", "-s", f"{sw * DOT}x{sh * DOT}", "-r", "30", "-i", "-", "-i", src, "-map", "0:v", "-map", "1:a", "-vf", f"pad={w}:{h}", "-c:v", "libx264", "-crf", "16", "-pix_fmt", "yuv420p", "-c:a", "copy", "-shortest", out], stdin=subprocess.PIPE) threshold = np.tile(BAYER, (sh // 8 + 1, sw // 8 + 1))[:sh, :sw] while chunk := reader.stdout.read(sw * sh): tone = np.clip((np.frombuffer(chunk, np.uint8).reshape(sh, sw).astype(np.float32) - BLACK) / (WHITE - BLACK), 0, 1) dots = np.where(tone > threshold, PAPER, INK).astype(np.uint8) writer.stdin.write(dots.repeat(DOT, axis=0).repeat(DOT, axis=1).tobytes()) writer.stdin.close() sys.exit(reader.wait() or writer.wait()) ``` ## More stylize and art - [Anime style **Anime style**](https://www.recharm.com/effects/anime-style) - [ASCII art **ASCII art**](https://www.recharm.com/effects/ascii-art) - [Blueprint **Blueprint**](https://www.recharm.com/effects/blueprint) - [Charcoal drawing **Charcoal drawing**](https://www.recharm.com/effects/charcoal-drawing) - [Claymation style **Claymation style**](https://www.recharm.com/effects/claymation-style) ## 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)