The CCTV & Fisheye Lens Defisher flattens severe barrel curvature from ultra-wide security cameras, action cams, dashcams, and fisheye lenses into rectilinear perspectives.

### Inverse Radial Distortion Correction Ultra-wide optical lenses distort straight linear features—such as doorframes, room corners, and license plates—into pronounced radial curves. The defisher applies inverse polynomial radial remapping to reverse barrel curvature: - **Radial Coordinate Transformation**: For every destination pixel $(x, y)$ centered at image midpoint $(x_c, y_c)$: $$r = \sqrt{(x - x_c)^2 + (y - y_c)^2}, \quad \theta = \text{atan2}(y - y_c, x - x_c)$$ - **Corrected Radial Radius**: $$r_{\text{corrected}} = r \times (1 + k \times r^2)$$ where distortion coefficient $k = (\text{Strength} / 100) \times 1.5 \times 10^{-6}$. - **Source Pixel Sampling**: Evaluates source coordinates $(x_c + r_{\text{corrected}}\cos\theta,\; y_c + r_{\text{corrected}}\sin\theta)$, transferring RGBA pixel values to the corrected canvas. - **Defish Strength Slider**: Allows tuning correction intensity between 0% (unmodified input) and 100% (maximum inverse warp).

### Worked Workflow Example 1. Upload a wide-angle action camera or doorbell camera snapshot showing curved horizontal fence lines. 2. Adjust the **Defish Strength** slider to approximately **45%**. 3. The inverse radial transformation re-aligns curved edges into straight lines across the frame center. 4. Preview the corrected rectilinear canvas instantly in your browser. 5. Click **Download Corrected Image** to export the rectilinear PNG file.

### In-Browser Canvas 2D Processing Pixel extraction and radial coordinate mapping execute 100% client-side via the HTML5 Canvas 2D ImageData API. No surveillance photos, forensic camera captures, or personal dashcam images are uploaded to any server.