---
title: "How to add a posterize with Claude (tested prompt and ffmpeg command)"
description: "The soft holographic backdrop breaks into flat patches of white and aqua, and the purple serum and its label turn into a few hard-edged bands of plum, violet and gray. Install one skill and ask Claude Code, or run the ffmpeg command we tested yourself."
url: https://www.recharm.com/effects/posterize
---

# How to add a posterize with Claude

The soft holographic backdrop breaks into flat patches of white and aqua, and the purple serum and its label turn into a few hard-edged bands of plum, violet and gray.

Made by the command 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 posterize to input.mp4
   Flat levels per color channel: 4
   Blur radius applied before banding, so grain doesn't break the band edges into speckles: 1.5
   ```

## 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 posterize 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 command.

| Setting  | Default | What it does                                                                                                   |
| -------- | ------- | -------------------------------------------------------------------------------------------------------------- |
| `LEVELS` | `4`     | Flat levels per color channel. 2 or 3 gives bold pop-art blocks; 6 or more keeps more of the original shading. |
| `SMOOTH` | `1.5`   | Blur radius applied before banding, so grain doesn't break the band edges into speckles. 0 turns it off.       |

## Without the skill

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

```
Apply a posterize effect to all of input.mp4, from the first frame to the last. First soften it slightly with a Gaussian blur of sigma 1.5 (ffmpeg's gblur) so grain doesn't speckle the band edges. Then cut each of the red, green and blue channels separately to 4 levels with the same curve (ffmpeg's lutrgb): a value v becomes floor(v*4/256)*255/3, so 0-63 becomes 0, 64-127 becomes 85, 128-191 becomes 170 and 192-255 becomes 255. Smooth gradients should turn into flat, hard-edged bands of color. Don't change anything else. Keep the size, frame rate, length and audio the same. Use ffmpeg and save it as output.mp4.
```

## Run it without Claude

This is the exact command we tested. Save it as `posterize.sh` and run:

```
sh posterize.sh input.mp4 output.mp4
```

```
#!/bin/sh
# Posterize: cut each color channel down to a few flat levels, so smooth gradients turn into hard-edged bands.
# Usage: sh posterize.sh input.mp4 output.mp4
set -e
IN="$1"; OUT="$2"
LEVELS=4     # flat levels per channel (4 gives 0, 85, 170 and 255); fewer makes bolder, more graphic bands
SMOOTH=1.5   # blur radius before banding, so grain doesn't break the band edges into speckles; 0 turns it off

# Split 0-255 into LEVELS equal slices and set every value in a slice to that slice's level.
CURVE="floor(val*$LEVELS/256)*255/($LEVELS-1)"
ffmpeg -y -i "$IN" -vf "gblur=sigma=$SMOOTH,lutrgb=r='$CURVE':g='$CURVE':b='$CURVE'" \
  -c:v libx264 -crf 18 -pix_fmt yuv420p -c:a copy "$OUT"
```

## 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)