ComparePicture

Pixel-by-pixel comparison, down to a single value

Exact mode counts every pixel whose colour differs at all. The inspector shows the two RGB values side by side at any point, magnified up to 20× with a pixel grid.

Private · Browser-based · No uploads

Two pictures in, every difference out.

  1. 1. Drop, paste or choose the earlier picture as A.
  2. 2. Add the later one as B — or drop both at once.
  3. 3. The comparison starts by itself; switch views any time.

PNG, JPEG, WebP, GIF (first frame), AVIF, BMP and HEIC where this browser can decode it. Different sizes are fine — they are aligned for you.

Both files are read by this page on your device. There is no upload step, because there is no server to upload to.

Or try an example pair

AReferenceChoose image Adrag & drop, or paste with Ctrl/⌘ VPress Enter to choose image A, or drop a file here.
BCandidateChoose image Bdrag & drop, or paste with Ctrl/⌘ VPress Enter to choose image B, or drop a file here.

What “identical” means here

With the Exact preset, two pictures are reported as pixel-identical only if they have the same dimensions and every compared pixel has the same red, green, blue and alpha value. That is a stronger statement than “visually identical”, and it is the one you want when checking that an export, a conversion or a cache returned exactly what went in.

Pixel-identical files can still differ. Metadata, compression settings and the bytes on disk are separate questions — the Metadata view answers them.

Reading a single pixel

Pick the inspect tool and click anywhere. The rail shows the frame coordinates, both colours as RGB and hex, the per-channel difference, luminance and alpha, how many of the surrounding 81 pixels changed, and the local structural similarity. Two magnifiers show the same neighbourhood from A and B at 5×, 10× or 20×. Past 12× zoom the main view draws a pixel grid as well.

Full resolution or fast

By default the comparison runs on a copy no larger than 2048 pixels on its long edge, which keeps phones responsive. For a true pixel-by-pixel answer on a larger picture, switch Analysis resolution to Full: every pixel is compared, up to 8192 px on the long edge on a computer.

Questions people ask

›Can I compare images pixel by pixel?

Yes. Choose the Exact preset (threshold 0, anti-aliasing tolerance off) and Full resolution. Every differing pixel is counted, highlighted and included in the exported mask.

›Why do two PNGs of the same screenshot differ?

Colour profiles, gamma chunks and different rendering of fonts or gradients produce one- or two-level differences that are invisible but real. Exact mode shows them; the UI Screenshot preset ignores them.