Diagonal Watermark Placement for AI Opt-Out
Learn how to use diagonal watermark placement to create a single large text overlay across your image. Ideal for bold statements that resist automated removal tools.
Detailed Explanation
Diagonal Watermark Placement
Diagonal placement renders a single large watermark text across the image from one corner to the other. It is the most visually prominent mode and sends an unmistakable message to both humans and automated systems.
When to Use Diagonal Mode
Diagonal placement works best when you want:
- Maximum visibility — The text spans the entire image, impossible to miss
- Simplicity — One large statement rather than a repeating pattern
- Quick application — No need to fine-tune spacing or grid density
How It Works Internally
The tool calculates the diagonal length of your image using the Pythagorean theorem:
diagonal = √(width² + height²)
It then sizes the text to span approximately 80-90% of this diagonal and rotates it to match the corner-to-corner angle:
angle = arctan(height / width)
The result is a single line of text that cuts across the image from bottom-left to top-right (or the reverse, depending on your rotation setting).
Customization Options
- Text content — "DO NOT USE FOR AI TRAINING" is the default, but you can customize it
- Font size — Auto-calculated from diagonal length, but you can override
- Opacity — 20-30% is recommended for diagonal mode since there is only one text instance
- Color — White with dark stroke works on most images; switch to black for light backgrounds
- Stroke width — Adding a contrasting outline ensures readability on varied backgrounds
Limitations
The main weakness of diagonal placement is that it leaves the corners and edges relatively clear. A determined scraper could crop a section from a corner that contains minimal watermark coverage. For higher security, consider combining diagonal with the tiled mode or adding symbol overlays in the corners.
Visual Impact
Because diagonal placement uses one large text, the visual impact is stronger than tiling at the same opacity level. Use a lower opacity (15-20%) if you want the image to remain pleasant for human viewers while still being clearly marked.
Use Case
An artist creating a tutorial wants to share a final artwork as a reference image in a blog post. They apply a single diagonal 'DO NOT USE FOR AI TRAINING' watermark to make their stance explicit while keeping the image useful for educational context.