Image difference comparison
Compare pixel differences between two local images, heatmaps, overlay previews, average differences, and dHash.
How to use image difference comparison
Image difference comparison processes input only in the current browser; no data is uploaded, networked, or saved.
Input content
Select two local images; the tool will first check their dimensions and decoding results.
Select a processing method
Generate a pixel heatmap, overlay image, and calculate fixed-size dHash distance.
Check and export
View size differences and metrics, and download a visualized difference image.
Limitations and Notes
- Different dimensions are not disguised as pixel-for-pixel matches; both pixel and thumbnail comparisons are subject to limits.
- The result is not a medical, safety, or forensic conclusion; compression, scaling, and color settings all affect the metrics.
- The tool only provides locally processed results; important configurations, secrets, documents, and published content must still be reviewed in the target environment.
FAQ
Will the input be uploaded to a server?
No. The page only uses browser memory, the local file API, and local resources already provided with the site.
Why are only some metrics shown when the dimensions differ?
A per-pixel heatmap requires corresponding pixels; different dimensions are reported separately as size differences, while safe thumbnail metrics are retained.
Why do the results still require manual review?
Edge-case syntax, regional standards, third-party readers, and target runtime environments may differ; the tool does not replace final validation.