The Specular Glare Subtractor softens blinding specular hotspots, direct camera flash flare, and glossy surface reflections in digital photographs.

### Pixel-Level Luminance Attenuation Algorithm Rather than applying a global exposure decrease that darkens midtones and shadows, the tool processes raw RGBA pixel data on an off-screen HTML5 canvas: 1. Luminance Cutoff Threshold: Derived dynamically from the user's glare reduction slider (0% to 100%): $$\text{Cutoff} = 255 - (\text{Glare Reduction} \times 0.90)$$ 2. Perceptual Luminance Evaluation: Evaluates standard ITU-R BT.601 perceptual brightness for each pixel: $$\text{Luminance} = 0.299R + 0.587G + 0.114B$$ 3. Adaptive Specular Softening: When pixel luminance exceeds the cutoff threshold, the excess brightness is attenuated: $$\text{Excess} = \text{Luminance} - \text{Cutoff}$$ $$\text{Factor} = \max\left(0.40, 1.0 - \frac{\text{Excess}}{120}\right)$$ $$R = \text{round}(R \times \text{Factor}), \quad G = \text{round}(G \times \text{Factor}), \quad B = \text{round}(B \times \text{Factor})$$ 4. Output Generation: The altered pixel buffer is drawn back onto canvas and exported as a clean PNG image.

### Real Highlight Reduction Example Consider a portrait photo with an overexposed flash hot spot on eyeglasses measuring luminance = 245: - Setting Glare Reduction to 60% establishes a cutoff of $255 - (60 \times 0.90) = 201$. - Luminance excess above threshold: $245 - 201 = 44$. - Attenuation factor: $1.0 - (44 / 120) \approx 0.633$. - The blinding white flare is darkened by ~37%, revealing underlying surface texture without clipping to muddy gray.

### Private On-Device Processing All image decoding, canvas pixel array reading, and PNG encoding execute entirely within your local web browser session. No photos are ever uploaded to remote servers.