A local-browser watermark tool with batch export, saved copyright settings, PNG copyright metadata, and an optional dual-axis mid-frequency ownership signature designed for better resistance to moderate JPEG compression. Visual text reveal and blind signature detection are separate features.
1 · Image and copyright name
Select multiple photos for batch processing. Use a full-resolution original. Processing stays in this browser.
This exact name is encoded as a repeated tiled pattern.
Lower is more discreet; higher is easier to reveal but more likely to tint pixels.
Up to 8×. Larger lettering can survive more resizing, but may exceed the photo dimensions and become easier to notice.
Luminance changes all RGB channels together, reducing dependence on fragile blue/chroma information. Strong compression may still destroy the mark.
Adds a seeded, zero-mean 16×16 dual-axis spatial-frequency pattern. Detector uses your copyright name as a key; no original required. This is an experimental correlation watermark, not a guarantee.
Higher values improve recovery but can make fine texture more visible.
Settings are stored only in this browser on this device.
Individual mode prepares separate PNGs. On iPhone, use Share all PNGs; on desktop, download individually or try Download all.
Choose one or more images and enter a copyright name.
On iPhone, the export button opens the Share sheet when supported. Choose “Save Image” or “Save to Files”.
Copyright metadata · PNG iTXt
Metadata settings are saved in this browser only.
PNG exports include Creator, Copyright, Rights, Software, and UTC export date as standardized text fields. Metadata can be removed by re-encoding.
2 · Reveal it
High-pass subtracts a blurred luminance background to emphasize subtle local changes, but photo texture may still obscure the mark. Compare with original isolates the embedded signal exactly, and only works while the original image is available.
Preview-only amplification. This does not change the downloaded file.
The reveal preview amplifies small pixel changes so you can inspect the signature.
3 · Pattern detection
The detector correlates a name-derived mid-frequency signature with the image. It does not require the original, but it assumes the image dimensions and orientation are unchanged. It can be tested on a JPEG re-export. A score alone is not proof of ownership.
Important limitations
The reveal pattern is encoded into the selected pixel channel(s) using a repeated text mask. There is no separate transparent text layer.
Normal appearance is controlled by a small per-pixel channel delta. The reveal preset isolates that channel and amplifies its contrast.
The mid-frequency signature is repeated over many 16×16 blocks and tested by correlation. It is more compression-tolerant in principle, but not cryptographically secure and can produce false positives.
JPEG recompression may preserve the signature, but resizing, cropping, rotation, aggressive denoising, or platform-specific processing may defeat it. The detector expects the original pixel grid and dimensions.
Important: This is an experimental visual watermark, not a secure or tamper-proof forensic standard. A low-strength channel mark can be removed, and aggressive reveal adjustments also amplify image noise and texture. Keep original RAW files, unwatermarked masters, dated exports, and a separate ownership record.