Image · Processed locally
Image Comparator
Find visual changes between an original image and a revised copy. Compare screenshots, design exports or compression results using a slider, overlays and pixel differences, then inspect the changed regions and download the results.
All tools- Choose files
- Set options
- Process locally
- Review & download
Or drop a file here. JPG, PNG or static WebP · up to 25 MB / 24 MP.
Original · first image
Or drop a file here. JPG, PNG or static WebP · up to 25 MB / 24 MP.
Comparison · second image
Fine-tune alignment
Move the comparison image on the shared canvas. Positive values move right or down; clipped edges are excluded.
No automatic registration. Transparent areas and extra canvas are white. Large images use a maximum 4 MP working canvas; small variations may be lost when downsampling.
Choose a file to begin.
Files stay in this browser’s memory. Originals are unchanged. Clear files or leave this page to release the studio’s copies.
See what changed between two image versions
Use the original as the first image and the revision as the comparison image. A matching crop and alignment make a comparison more useful: a one-pixel shift can mark edges across the whole picture. The tool compares decoded image pixels, not the meaning of a design or the words inside it.
How to use Image Comparator
- Choose the original image and Choose comparison image, or try the sample differences. Each must be JPG, PNG or static WebP within 25 MB and 24 megapixels.
- Choose Image alignment: align top left, centre both images on a shared canvas, or resize the comparison to the original dimensions. Fine-tune alignment offers horizontal and vertical pixel offsets.
- Set Ignore channel differences up to. A lower value reveals smaller pixel changes; a higher value can reduce noise from encoding or antialiasing. Select Compare images.
- Switch between Highlights, Side by side, Slider, Fade, Heatmap, Subtract and optional Flicker. Zoom or pan, use Next change to inspect regions, then download the PNG views or comparison-report.json.
Choose a view for the question you are asking
Use Slider or Fade to inspect an edit in context. Highlights and Heatmap make changed areas easier to locate. Subtract shows identical pixels as black. Side by side keeps both versions visible. Flicker is optional and alternates images; avoid it if flashing or motion is uncomfortable, and use a static view instead.
Understand the changed-pixel percentage
The percentage counts pixels whose largest RGB-channel difference exceeds your threshold on the working canvas. It is not a perceptual similarity score, proof of plagiarism or a judgement of image quality. Transparent areas and extra canvas are compared on white. Resizing, alignment and downsampling affect the result.
Supported files and limits
- Comparison uses a working canvas of at most 4 megapixels and 8192 pixels per edge. Exports and statistics describe that working size, so tiny changes can disappear when large images are downsampled.
- The report counts connected change regions and includes the largest 200. Filtering the region list changes what is displayed, not the underlying changed-pixel statistics.
- There is no automatic registration, perspective correction, OCR comparison or EXIF comparison. This tool does not compare PDFs, animated images or original file bytes.
Local processing and privacy
ToolDock processes the files you select in your browser and does not upload them for this tool. Originals stay unchanged. Loading the website, processing code and Google libraries still makes network requests; local file processing does not mean a network-silent page. Read what is requested and stored.
Questions about Image Comparator
Why do almost all pixels appear different?
Check the crop, dimensions and alignment first. A shifted screenshot, a resized export, a different colour profile or compression noise can affect many pixels even when the content looks similar. Try the alignment controls and an appropriate threshold; do not hide meaningful edits by raising it too far.
Does 0% changed prove the files are identical?
No. The displayed percentage is rounded; check the changed-pixel count for tiny differences. Even a zero changed-pixel count means only that no working-canvas difference exceeded the selected threshold. Downsampling, white compositing or resizing can hide differences, and file metadata is not compared. It is not a byte-for-byte file check.
Can it compare the text inside screenshots?
It can highlight changed pixels around text, but it does not recognize or compare words. Use Image to Text separately if you need a plain-text transcription of a supported image.
What can I download?
The result includes working-size PNGs such as difference, region and subtraction views, plus a JSON report with settings, changed-pixel statistics and the largest region bounds. Review those outputs in the context of your chosen alignment and threshold.