Image Watermark Detector
Detect 5 watermark types in any image: visible overlay, LSB tracking, DWT+DCT invisible copyright, AI generation markers, and EXIF metadata. No upload.
Drop your image here or click to browse
PNG, JPEG, BMP, WebP · Max 50 MB
All processing runs locally — your image never leaves your device
100% Client-Side Processing
Your image is decoded using the Canvas API in this browser tab. Nothing is uploaded. Output is always lossless PNG — watermarks are preserved exactly.
How to Check if an Image Has a Watermark (4 steps)
- Upload any PNG or JPEG image — detection starts automatically across all 5 watermark types simultaneously.
- The simple result shows a plain-language verdict: is this image copyright protected? Risk level HIGH/MEDIUM/LOW.
- Expand 'Full technical details' for per-category confidence scores, the watermark location heatmap, and extracted EXIF metadata.
- Download the detection report as JSON documentation — useful as evidence of due diligence before commercial use.
5 Watermark Detection Types
| Category | Technique | Speed | Best For |
|---|---|---|---|
| Visible watermark | Edge contrast and alpha-channel analysis to detect text/logo overlays and semi-transparent regions | < 0.3 seconds | Check for obvious copyright marks, logo overlays, tiled patterns |
| LSB steganography | Chi-square analysis per R/G/B channel — detects sequential and adaptive LSB steganographic embedding | < 0.5 seconds | CTF challenge images, tracking watermarks in spatial domain |
| DWT+DCT frequency watermark | QIM quantization pattern analysis in DCT coefficients of Haar LL subband | ~1–2 seconds | Professional invisible copyright protection (this tool, watermark.ninja, etc.) |
| AI generation markers | Statistical power spectrum and cross-channel correlation analysis for SynthID-like frequency perturbations | ~2–3 seconds | AI content policy compliance, editorial use verification |
| EXIF / metadata | Parses EXIF Copyright, EXIF Artist, XMP Rights, XMP Creator URL, IPTC Byline fields | < 0.1 seconds | Most reliable — direct copyright declaration in file header |
Frequently Asked Questions
If the detector shows no watermark, is the image free to use?
No. Absence of a detectable watermark does NOT mean an image is public domain or free to use. Copyright exists automatically at creation — no watermark required. Always verify the image's source and license before commercial use.
What does 'AI generation markers detected' actually mean?
This tool uses statistical analysis of pixel patterns to detect anomalies consistent with AI watermarking techniques (like Google's SynthID). It is probabilistic — not definitive. A score of 0.7 means statistical anomalies were found, not that the image is confirmed AI-generated. Only the original AI system can confirm with certainty.
Can this detector verify watermarks I embedded with the Watermark Embedder?
Yes — DWT+DCT detection will flag invisible watermarks embedded by this tool. However, the detector cannot read WHAT the invisible watermark says (that requires the companion Watermark Verifier which knows the original text). The detector only confirms the watermark's presence.
Why is my image flagged HIGH risk when it looks unprotected?
Multiple detectors may have flagged low-confidence signals that aggregate to HIGH. Check the individual detector confidence scores in Full Technical Details. If no single detector exceeds 0.7 confidence, the HIGH risk rating may be from multiple weak signals rather than confirmed protection.
Is this image uploaded to a server during analysis?
Never. All five detection algorithms run in a WebWorker in your browser. The image never leaves your device — even the SHA-256 hash is computed locally. This is the only watermark detector that guarantees client-side processing.