Add Text Watermark
Apply responsive text stamps on images to claim copyright ownership before uploading publicly.
Ad placeholder slot
Medium Rectangle (300x250)
Protect Creative IP with Local Text Watermarking: Alpha Blending & Placement Geometry
Sharing digital illustrations, photography, or interface designs on websites exposes work to scrapers and theft. Overlaying text watermarks guarantees your brand is credited. img-converter.in runs all canvas layering operations locally on the graphics rendering hardware of your device, preventing exposure to external networks.
1. Alpha Blending and Transparency Mathematics
To overlay a watermark cleanly without obscuring the underlying art, our script implements **Alpha Blending**. The rendering context blends the text pixels with the source image pixels by computing final RGBA color values for each pixel $(x, y)$:
This alpha parameter determines opacity. Adjusting the slider scales alpha between $0.1$ and $1.0$, instructing the browser's GPU exactly how to calculate the pixel color mix.
2. Grid Coordinate Geometry and Font Scaling
To ensure watermarks appear identical regardless of target image dimensions, we calculate coordinate vectors dynamically. Instead of fixed pixel coordinates, fonts are scaled using a percentage of the total image width:
When placing text in standard positions (like the bottom-right corner), we calculate coordinate offsets dynamically, applying proportional margins so that watermarks remain perfectly aligned without slipping outside the boundary edges.
Optimal Placement Guidelines
Where you place your brand stamp determines how easily it can be cropped out. Follow these guidelines depending on your asset usage: