Nimbus Major Image Effect Generator

function processImage(originalImg, bloomStrength = 15, glowIntensity = 0.6, vignetteStrength = 0.8, tintColor = "rgba(255, 230, 200, 0.25)") {
    // Create the main canvas
    const canvas = document.createElement('canvas');
    const width = originalImg.width;
    const height = originalImg.height;
    canvas.width = width;
    canvas.height = height;
    const ctx = canvas.getContext('2d');

    // 1. Draw the original base image with some basic enhancements (contrast/saturation)
    ctx.filter = 'contrast(1.1) saturate(1.2) brightness(1.02)';
    ctx.drawImage(originalImg, 0, 0, width, height);

    // 2. Create the "Nimbus" (glowing halo/bloom) effect using an offscreen canvas
    const bloomCanvas = document.createElement('canvas');
    bloomCanvas.width = width;
    bloomCanvas.height = height;
    const bloomCtx = bloomCanvas.getContext('2d');

    // Apply a blur for the glowing effect
    bloomCtx.filter = `blur(${Number(bloomStrength)}px) brightness(1.1)`;
    bloomCtx.drawImage(originalImg, 0, 0, width, height);

    // Blend the glow onto the main canvas using 'screen' to brighten and bloom highlights
    ctx.filter = 'none';
    ctx.globalCompositeOperation = 'screen';
    ctx.globalAlpha = Number(glowIntensity);
    ctx.drawImage(bloomCanvas, 0, 0, width, height);

    // 3. Apply the "Major" overlay tint for an ethereal or slightly vintage color grade
    ctx.globalCompositeOperation = 'overlay';
    ctx.globalAlpha = 1.0;
    ctx.fillStyle = String(tintColor);
    ctx.fillRect(0, 0, width, height);

    // 4. Create and apply a vignette to frame the glowing effect centrally
    ctx.globalCompositeOperation = 'multiply';
    const cx = width / 2;
    const cy = height / 2;
    // Calculate the maximum distance from center to corner
    const radius = Math.sqrt(cx * cx + cy * cy);
    
    const gradient = ctx.createRadialGradient(cx, cy, radius * 0.3, cx, cy, radius);
    gradient.addColorStop(0, 'rgba(0, 0, 0, 0)');
    gradient.addColorStop(0.6, `rgba(0, 0, 0, ${Number(vignetteStrength) * 0.3})`);
    gradient.addColorStop(1, `rgba(0, 0, 0, ${Number(vignetteStrength)})`);
    
    ctx.fillStyle = gradient;
    ctx.fillRect(0, 0, width, height);

    // Reset compositing
    ctx.globalCompositeOperation = 'source-over';
    
    return canvas;
}