- Does this tool upload my images anywhere?
- No. All processing happens inside your browser using the HTML5 Canvas API. Your images are read from disk into memory and never sent to any server. You can use this tool entirely offline once the page has loaded.
- What image formats are supported?
- Any format your browser can decode works: JPEG, PNG, WebP, HEIC (on Safari), GIF, AVIF, and BMP. For best results use a high-contrast scan or photo taken in good lighting — the cleaner the scan, the easier it is to spot stroke differences in the overlay.
- How do I use the Overlay mode to practise tracing?
- Upload the reference image as "Reference" and leave "Your writing" blank (or use a blank/light practice sheet photo). In Overlay mode, set the reference on top at around 30-50% opacity. Print the overlay view and practise tracing the ghosted strokes. Alternatively, take a photo of your trace attempt, upload it as "Your writing", and switch back to Side by Side to compare.
- The two images are different sizes — will they align correctly?
- In Side by Side mode each image fills its own half-panel, so size differences do not matter. In Overlay mode both images are scaled to fill the canvas at the same zoom level. If your practice sheet is photographed at a very different scale from the reference, use the Zoom controls to scale the view until the letterforms look roughly matched in size. For precise work, crop and resize your images to the same pixel dimensions before uploading.
- Can I annotate only one panel in Side by Side mode?
- Yes. When you draw an arrow or circle, the annotation is pinned to the canvas coordinate where you draw it, which maps to the left panel (reference) or right panel (practice) depending on where you click. As you zoom and pan, all annotations move with the images so they stay attached to the correct region.