Dzzz

Image Diff

On-device

See exactly what changed between two images — compared entirely on your device.

Compare two images entirely on your device: see a live percentage of pixels changed, a count of distinct changed regions with jump-to-next navigation, and five ways to look at the difference — side by side, a swipe slider, an onion-skin opacity blend, a numbered difference-region overlay, and an A/B blink. Adjust sensitivity and choose whether to ignore anti-aliasing noise. Nothing is uploaded.

About this tool

What you provide

  • Two images in any format your device can decode — JPEG, PNG, WebP, GIF or AVIF.
  • A sensitivity slider (perceptual colour-distance threshold) and an ignore-anti-aliasing toggle.
  • For mismatched sizes, a choice between comparing the shared overlap or scaling image B to match.

What you get

  • A live percentage of pixels changed and a count of distinct changed regions.
  • Five view modes: side by side, swipe, onion-skin opacity blend, a numbered difference-region map, and A/B blink.
  • Prev/next navigation over the changed regions, sorted largest first.

Limits

  • The difference view shows bounding boxes around changed regions, not a per-pixel heat map.
  • Very large images may take a moment to decode and compare — everything still runs on your device.
  • Comparison is visual only; it does not read metadata, EXIF data or file structure.

How to use it

  1. Choose image A

    Pick the first image from your device — it's decoded locally and never leaves your device.

  2. Choose image B

    Pick the second image to compare it against. If the two differ in size, a banner appears with an Overlap/Scale choice.

  3. Tune sensitivity

    Adjust the sensitivity slider and, if needed, toggle Ignore anti-aliasing noise to control how strict the comparison is.

  4. Pick a view mode

    Switch between side by side, swipe, onion skin, the difference map, or blink to see the change in the way that's clearest.

  5. Step through the differences

    Use Previous/Next to jump between changed regions, sorted largest first, with the current region highlighted.

Frequently asked questions

Are my images uploaded anywhere?

No. Both images are decoded and compared entirely on your device using JavaScript — nothing is sent to a server, and it works offline once the page has loaded.

Why doesn't a resized or re-compressed image show as completely different?

The comparison uses a perceptual colour distance rather than exact byte equality, so ordinary resampling or compression noise stays under the sensitivity threshold while a real edit still crosses it. Turning off “Ignore anti-aliasing noise” makes the comparison stricter.

What happens if the two images aren't the same size?

A banner tells you the two sizes and lets you choose: compare only the top-left region the images have in common (Overlap), or resample image B onto image A's grid first (Scale to match). Neither option is applied silently — the choice and the exact compared size are always shown.

What's the difference between the five view modes?

Side by side and Swipe show both full images; Onion skin fades one over the other with an opacity slider; Difference map draws a numbered box over each changed region on image A; Blink alternates the two images on a timer you control (or a manual button if your device prefers reduced motion).