Golden Hour Glow Image Effect Generator

function processImage(originalImg, intensity = 0.6, warmth = 0.7) {
    // Restrict parameters to sensible boundaries for safe math
    const safeIntensity = Math.max(0, Math.min(1, Number(intensity) || 0));
    const safeWarmth = Math.max(0, Math.min(1, Number(warmth) || 0));

    const width = originalImg.width;
    const height = originalImg.height;

    // Create the main canvas
    const canvas = document.createElement('canvas');
    canvas.width = width;
    canvas.height = height;
    const ctx = canvas.getContext('2d');

    // 1. Base Image - Boost contrast and saturation slightly
    ctx.filter = `contrast(${1 + 0.15 * safeIntensity}) saturate(${1 + 0.4 * safeWarmth})`;
    ctx.drawImage(originalImg, 0, 0);
    ctx.filter = 'none';

    // 2. Warm Color Overlay
    // Soft-light blends gently into the mid-tones, increasing warmth
    ctx.globalCompositeOperation = 'soft-light';
    ctx.fillStyle = `rgba(255, 140, 0, ${safeWarmth * 0.5})`; // Golden/orange tint
    ctx.fillRect(0, 0, width, height);

    // 3. Directional Sun Overlay (Radial Gradient)
    // Simulates a sun source coming from the top center
    ctx.globalCompositeOperation = 'overlay';
    const sunGradient = ctx.createRadialGradient(
        width / 2, 0, height * 0.05,        // Inner circle (top center)
        width / 2, 0, Math.max(width, height) // Outer circle
    );
    sunGradient.addColorStop(0, `rgba(255, 210, 120, ${safeWarmth * 0.6})`);
    sunGradient.addColorStop(0.5, `rgba(255, 120, 20, ${safeWarmth * 0.2})`);
    sunGradient.addColorStop(1, `rgba(0, 0, 0, 0)`);
    
    ctx.fillStyle = sunGradient;
    ctx.fillRect(0, 0, width, height);

    // 4. Bloom / Glow Effect
    // Draw the image again with 'screen' blending and high blur to create the soft, glowing light
    ctx.globalCompositeOperation = 'screen';
    ctx.globalAlpha = safeIntensity * 0.45;
    
    // Calculate a proportional, bounded blur radius
    const blurRadius = Math.min(Math.max(width, height) * 0.03 * safeIntensity, 60); 
    
    // Add sepia to the glow to make it extra warm and bright
    ctx.filter = `blur(${blurRadius}px) contrast(1.3) sepia(${0.6 * safeWarmth})`;
    ctx.drawImage(originalImg, 0, 0);

    // Reset context before adding the final touch
    ctx.globalAlpha = 1.0;
    ctx.filter = 'none';

    // 5. Subtle Vignette
    // Focuses the light on the center/top by gently darkening the edges
    const vignette = ctx.createRadialGradient(
        width / 2, height / 2, Math.max(width, height) * 0.4,
        width / 2, height / 2, Math.max(width, height) * 0.85
    );
    vignette.addColorStop(0, 'rgba(0,0,0,0)');
    vignette.addColorStop(1, `rgba(40,10,0,${0.35 * safeIntensity})`); // Warm dark vignette
    
    ctx.globalCompositeOperation = 'multiply';
    ctx.fillStyle = vignette;
    ctx.fillRect(0, 0, width, height);

    return canvas;
}