Lights Out Movie Poster

async function processImage(originalImg, darknessLevel = "0.85", contrastLevel = "1.6", addPosterText = "true") {
    // Parse parameters
    const darkness = Math.min(1, Math.max(0, parseFloat(darknessLevel) || 0.85));
    const contrast = parseFloat(contrastLevel) || 1.6;
    const includeText = String(addPosterText).toLowerCase() === "true";

    // Setup 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');

    // Draw original image
    ctx.drawImage(originalImg, 0, 0);

    // Get pixel data
    const imgData = ctx.getImageData(0, 0, width, height);
    const data = imgData.data;

    // Apply "Lights Out" Color Grading & Contrast
    for (let i = 0; i < data.length; i += 4) {
        let r = data[i];
        let g = data[i + 1];
        let b = data[i + 2];

        // 1. Contrast Adjustment (Center around 128 mid-gray)
        r = ((r / 255 - 0.5) * contrast + 0.5) * 255;
        g = ((g / 255 - 0.5) * contrast + 0.5) * 255;
        b = ((b / 255 - 0.5) * contrast + 0.5) * 255;

        // Clamp values
        r = Math.min(255, Math.max(0, r));
        g = Math.min(255, Math.max(0, g));
        b = Math.min(255, Math.max(0, b));

        // 2. Calculate Luminance
        let lum = 0.299 * r + 0.587 * g + 0.114 * b;

        // 3. Cinematic Horror Color Grading (Teal Shadows, Pale Yellow Highlights)
        
        // Deepen shadows and tint them cyan/teal
        if (lum < 128) {
            let shadowIntensity = 1 - (lum / 128); // 1 at pitch black, 0 at mid-gray
            r -= shadowIntensity * 40;
            g += shadowIntensity * 15;
            b += shadowIntensity * 40;
        } 
        // Tint highlights slightly sickly warm
        else {
            let highlightIntensity = (lum - 128) / 128; // 0 at mid-gray, 1 at pure white
            r += highlightIntensity * 10;
            g += highlightIntensity * 10;
            b -= highlightIntensity * 20;
        }

        // Clamp again after color grading
        r = Math.min(255, Math.max(0, r));
        g = Math.min(255, Math.max(0, g));
        b = Math.min(255, Math.max(0, b));

        // 4. Overall Darkening
        const darkeningFactor = 1 - (darkness * 0.4); 
        r *= darkeningFactor;
        g *= darkeningFactor;
        b *= darkeningFactor;

        // 5. Add Film Grain / Noise
        const noise = (Math.random() - 0.5) * 25; // Random value between -12.5 and +12.5
        r += noise;
        g += noise;
        b += noise;

        // Assign back to data array
        data[i] = r;
        data[i + 1] = g;
        data[i + 2] = b;
    }

    // Put modified pixels back
    ctx.putImageData(imgData, 0, 0);

    // Apply Heavy "Lights Out" Vignette / Spotlight Effect
    const centerX = width / 2;
    // Spotlight slightly higher than center (usually where faces are)
    const centerY = height * 0.4;
    const maxRadius = Math.max(width, height);

    const gradient = ctx.createRadialGradient(centerX, centerY, maxRadius * 0.1, centerX, centerY, maxRadius * 0.8);
    gradient.addColorStop(0, 'rgba(0, 0, 20, 0)'); // Clear/slight blue tint in center
    gradient.addColorStop(0.4, `rgba(0, 5, 15, ${darkness * 0.7})`); // Mid-darkness
    gradient.addColorStop(0.8, 'rgba(0, 0, 0, 0.98)'); // Almost pitch black
    gradient.addColorStop(1, '#000000'); // Pitch black edges

    ctx.fillStyle = gradient;
    ctx.fillRect(0, 0, width, height);

    // Add subtle film scratch overlays
    ctx.lineWidth = 1;
    const numScratches = Math.floor(width * 0.05); // Density based on image width
    for(let i = 0; i < numScratches; i++) {
        let x = Math.random() * width;
        // Mostly dark scratches, occasionally light
        ctx.strokeStyle = Math.random() > 0.85 ? 'rgba(255, 255, 255, 0.03)' : 'rgba(0, 0, 0, 0.15)';
        ctx.beginPath();
        ctx.moveTo(x, 0);
        let y = 0;
        while(y < height) {
            y += Math.random() * 50;
            ctx.lineTo(x + (Math.random() - 0.5) * 3, y); // Slight horizontal waving
        }
        ctx.stroke();
    }

    // Add Movie Poster Text
    if (includeText) {
        // Prepare text dimensions
        const mainTitleSize = Math.max(24, Math.floor(width * 0.09));
        const subTitleSize = Math.max(12, Math.floor(width * 0.025));
        
        ctx.textAlign = "center";
        
        // Attempt to use letter spacing if supported natively by the canvas API in modern browsers
        if ('letterSpacing' in ctx) {
            ctx.letterSpacing = `${Math.floor(mainTitleSize * 0.25)}px`;
        }

        // Draw Subtitle / Tagline
        ctx.textBaseline = "bottom";
        ctx.font = `bold ${subTitleSize}px Arial, sans-serif`;
        ctx.fillStyle = "rgba(220, 230, 240, 0.7)"; // Ghostly cool-white
        ctx.shadowColor = "rgba(100, 150, 255, 0.3)";
        ctx.shadowBlur = 5;
        const taglineY = height - (mainTitleSize * 1.5) - (height * 0.03);
        ctx.fillText("YOU WERE RIGHT TO BE AFRAID OF THE DARK.", width / 2, taglineY);

        // Draw Main Title
        ctx.font = `bold ${mainTitleSize}px "Helvetica Neue", Helvetica, Arial, sans-serif`;
        ctx.fillStyle = "#FFFFFF"; // Stark white
        // Apply a glowing/light bleed effect from the dark
        ctx.shadowColor = "rgba(255, 255, 255, 0.6)";
        ctx.shadowBlur = 15;
        const titleY = height - (height * 0.05);
        ctx.fillText("LIGHTS OUT", width / 2, titleY);
        
        // Overlay a second layer for the title with slightly dark gradient to mimic rough lighting
        const textGradient = ctx.createLinearGradient(0, titleY - mainTitleSize, 0, titleY);
        textGradient.addColorStop(0, "rgba(255, 255, 255, 1)");
        textGradient.addColorStop(1, "rgba(150, 150, 160, 1)");
        ctx.fillStyle = textGradient;
        ctx.shadowBlur = 0; // Disable blur for sharp overlay
        ctx.fillText("LIGHTS OUT", width / 2, titleY);
        
        // Reset letter spacing
        if ('letterSpacing' in ctx) {
            ctx.letterSpacing = "0px";
        }
    }

    return canvas;
}