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diff · pixel · visual · local

Compare two images and highlight pixel differences

Pixel-by-pixel diff with a desaturated base and red highlights where the images differ. Runs locally.

Image Diff
Image A
—
pick
Image B
—
pick
Pixels different
—
—
% different
—
threshold 8/255
input · image
Image A

image/* · runs locally · nothing uploaded

Image B

image/* · runs locally · nothing uploaded

output · preview
Preview appears here
Quick Start

How it works

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

  1. 01

    Load image A

    The first image is the reference shown desaturated under the diff highlight.

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

    Auploadcanvaslocaldecode
    image · bytesA · loaded
    load: ref.png
    loaded · decodedcanvas · ready
  2. 02

    Load image B

    The comparison image. Dimensions must match A.

    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.

    Boptionslive previewencoderquality
    image · tunableB · live
    load: target.png
    options applied · liveencoder · live
  3. 03

    Pixel compare

    RGB deltas summed; pixels where Δ > 8 are painted bright red.

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

    scanrenderCanvas 2Dpreviewpx-perfect
    Δ · resampled> 8 · px-perfect
    |dR|+|dG|+|dB| > 8
    preview · livepx-perfect
  4. 04

    Download diff PNG

    Save the overlay for tracking visual-regression changes.

    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
    diff.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.

Related toolsSliderHash CompareELADimensionsStitcherHex Viewer
Use Cases

When to use this tool

Common workflows it speeds up.

Visual regression

Spot pixel drift between deploy snapshots. 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

Design review

Quickly find what changed between revisions. 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

Render testing

Detect rendering quirks across browsers. 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

Asset re-export

Confirm a re-exported asset matches the original. 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

Build artifact check

Verify build output matches a golden image. 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

AB testing

Visualize how two variants differ visually. 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

Pixel-by-pixel comparison requires identical dimensions. Resize one image first or use the Comparison Slider.
RGB delta sum > 8 counts as different — small enough to catch real changes, large enough to ignore tiny encoding noise.
Only RGB is compared. Alpha differences don't count toward the diff.
Not in the UI — it's a fixed 8/255 sum, which works well for screenshots.
No. Everything runs locally in your browser.
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