posterize · levels · png · local

Reduce color levels with posterize

Quantize each color channel to N evenly-spaced levels for a flat poster look. 2 = 8 colors total; 8 = 512. Runs locally.

Posterize Effect
Source
—
no file
Levels
4
per channel
Total colors
64
palette
Output
—
png
Levels:4
input · image

image/* · runs locally · nothing uploaded

output · preview
Original
—
4 levels
—
Quick Start

How it works

Pick an image, tune the options, then download the result. Everything runs in your browser.

  1. 01

    Pick an image

    Any image works — graphic photos posterize best.

    Files stay in memory as an HTMLImageElement — the original bytes are never uploaded, and EXIF metadata is preserved until you explicitly transform it.

    uploadcanvaslocaldecode
    input · bytesimage · loaded
    source.png
    loaded · decodedcanvas · ready
  2. 02

    Set levels

    2 produces 2³ = 8 colors; 8 levels gives 512 total.

    Encoder quality is exposed where the format supports it — JPEG and WebP get a 0–1 quality slider; PNG is lossless. Options re-render the canvas immediately.

    levelsoptionslive previewencoderquality
    levels · tunable4 · live
    q(v) = round(v / 255 * (3)) / 3 * 255
    options applied · liveencoder · live
  3. 03

    Preview the flatness

    Pop-art look becomes obvious below 4 levels.

    Pixel work runs on the Canvas 2D context — drawImage resamples with the browser’s bilinear filter and getImageData/putImageData back per-pixel passes.

    previewrenderCanvas 2Dpx-perfect
    palette · resampled64 · px-perfect
    total colors
    preview · livepx-perfect
  4. 04

    Download PNG

    Save the posterized image. PNG keeps the crisp transitions.

    Downloads ship via a hidden anchor with an object URL — no server round-trip, and the file on disk is untouched. The output filename inherits a sensible suffix.

    exportdownloadblobclient-sideobject URL
    ok · blobready · saved
    posterized.png
    shipped · ready to shipsuccess
Pro tips

Browser-only image work that scales

Convert with quality control

JPEG/WebP let you pick a 0–1 quality. Default 0.92 is a good compromise of size and visible quality.

PNG isn’t free

Use PNG only for transparency or sharp edges. For photos, WebP is smaller at the same perceived quality.

Strip EXIF for privacy

Photo EXIF often contains GPS, camera model, and timestamps. Strip before sharing public uploads.

Watch the colour profile

Convert to sRGB before web export. Wide-gamut images render oversaturated in non-managed browsers.

AVIF when it’s available

AVIF beats WebP on size at the same quality. Detect support via <picture> with fallbacks.

Lazy-load below the fold

Add loading="lazy" on <img>. The browser handles scheduling — no IntersectionObserver needed.

Use Cases

When to use this tool

Common workflows it speeds up.

Poster art

Screen-print-style flat color reduction. Decoded into a Canvas 2D context — original bytes never leave the tab, so you can process customer-uploaded photos, internal screenshots, or sensitive diagrams without privacy concerns.

px-perfect

Comic effects

Cell-shaded comic-book panels from photos. Encoders expose quality 0–1 where the format supports it (JPEG, WebP); PNG and AVIF stay perceptually lossless. Pick 0.85 for web, 0.95 for archival, 0.7 for thumbnails.

quality-tunable

Branding

Reduce a photo to your brand's color count. Pair with the EXIF Stripper before sharing user-uploaded photos publicly. Camera serial numbers, GPS coordinates, and timestamps often hide in image metadata and leak more than the picture itself.

format-aware

Visual abstraction

Simplify illustrations for icons. Output preserves colour profile (sRGB) so it renders consistently across browsers, monitors, and print pipelines. Wide-gamut workflows can opt into Display P3 for modern Apple devices.

EXIF-safe

Print prep

Cleaner output for limited-color printing. Re-runs only on option changes, never on window resize, so the canvas stays responsive on large images. drawImage uses the browser's bilinear filter for fast resampling.

client-side

Compression hint

Pre-quantize before PNG palette compression. Downloads as .png, .jpg, .webp, or .avif with the correct MIME so editors apply native handling on save. The filename inherits a sensible suffix derived from the input.

compression-ready
FAQ

Frequently asked questions

How many discrete values each color channel is rounded to. 2 levels per channel means 8 total colors (2x2x2); 8 levels gives 512.
Yes — alpha channel is untouched.
2 levels collapses each channel to off/on, giving only 8 saturated colors.
PNG, lossless.
No. Everything runs locally in your browser.
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