This tool removes the SynthID invisible watermark from images generated by Google Gemini, Nano, and Imagen. Built on codeaashu/RemoveBanana, it uses a reverse alpha-blending algorithm to invert the watermark at the pixel level and restore the original colors. All processing runs in the browser — images are never uploaded. Supported formats: JPG, PNG, WebP.
How the removal works
SynthID embeds a semi-transparent white pattern in the bottom-right corner of generated images. The removal works by loading a pre-stored watermark template (48×48 px or 96×96 px), then solving the standard alpha compositing equation in reverse for each affected pixel: given the composited pixel value and the watermark's alpha value, the tool calculates what the original color was before blending. This is a deterministic math operation — on uncompressed images it is lossless.
Automatic watermark size selection
The tool runs a normalized cross-correlation against both the 48 px and 96 px templates in the image's bottom-right region, then picks the template with the higher correlation score. No manual selection is needed:
- 48 px template (32 px from right/bottom edge) — typically found on smaller generated images
- 96 px template (64 px from right/bottom edge) — typically found on images 1024 px wide and above
Viewing the result
After upload the tool shows a drag-to-compare panel. Slide the divider left and right to see the pixel-level difference in the watermark area. Download the cleaned image as a PNG once satisfied.
Works well for
- Images generated directly from Gemini, Nano, or Imagen
- Lossless or minimally compressed originals
- Full-resolution downloads without heavy re-encoding
Will not work for
- Visible text watermarks, logos, or overlaid graphics
- Images not from Gemini/Nano/Imagen
- Files that have been heavily re-saved as JPEG (compression noise interferes)
- Images with large crops removing the bottom-right corner