When this tool is useful
Finding changed pixels between two exports, revisions, screenshots, or processing results when both images should align exactly.
How local processing works
After signature validation and local decoding, the browser compares alpha and alpha-premultiplied RGB at aligned pixels, deliberately ignoring hidden RGB in fully transparent pixels where alpha is zero. It counts changed pixels, calculates MAE, RMSE, and maximum channel delta, and encodes a separate difference heatmap.
How to use it
- Prepare Compare two images: Work from a copy and confirm source order, exact decoded width and height, alpha and transparent areas, the changed-pixel threshold, channel metrics, and heatmap interpretation. Keep the source unchanged.
- Apply Compare two images: Process locally in the browser. After signature validation and local decoding, the browser compares alpha and alpha-premultiplied RGB at aligned pixels, deliberately ignoring hidden RGB in fully transparent pixels where alpha is zero. It counts changed pixels, calculates MAE, RMSE, and maximum channel delta, and encodes a separate difference heatmap.
- Download and verify: Save under a new name. Confirm equal dimensions, inspect both originals beside the heatmap at 100%, and treat every metric as decoded-pixel evidence rather than a score that says which image is better.
Important limitations
The metrics describe alpha and premultiplied-RGB differences, not every stored RGB byte and not perceptual quality, semantic meaning, authenticity, or edit intent. Hidden RGB in fully transparent pixels is intentionally ignored; different dimensions are rejected, and color-profile decoding can affect values.
Verify the downloaded result
Confirm equal dimensions, inspect both originals beside the heatmap at 100%, and treat every metric as decoded-pixel evidence rather than a score that says which image is better.
Private by design
Your files stay in this browser. The tool does not upload the source or output to our servers.
Questions and answers
When should I use Compare two images?
Finding changed pixels between two exports, revisions, screenshots, or processing results when both images should align exactly.
What does Compare two images change?
After signature validation and local decoding, the browser compares alpha and alpha-premultiplied RGB at aligned pixels, deliberately ignoring hidden RGB in fully transparent pixels where alpha is zero. It counts changed pixels, calculates MAE, RMSE, and maximum channel delta, and encodes a separate difference heatmap.
Which limits and settings matter?
source order, exact decoded width and height, alpha and transparent areas, the changed-pixel threshold, channel metrics, and heatmap interpretation. The metrics describe alpha and premultiplied-RGB differences, not every stored RGB byte and not perceptual quality, semantic meaning, authenticity, or edit intent. Hidden RGB in fully transparent pixels is intentionally ignored; different dimensions are rejected, and color-profile decoding can affect values.
How do I verify the result?
Confirm equal dimensions, inspect both originals beside the heatmap at 100%, and treat every metric as decoded-pixel evidence rather than a score that says which image is better.