Image G-Major 3 Effect Generator

function processImage(originalImg, hueRotateDeg = 140, saturatePercent = 300, contrastPercent = 150, invertPercent = 100, mirrorMode = "none") {
    const canvas = document.createElement('canvas');
    const width = originalImg.width;
    const height = originalImg.height;
    
    canvas.width = width;
    canvas.height = height;
    
    const ctx = canvas.getContext('2d');
    
    // Apply classic "G-Major 3" visual style (heavy inversion, hue-shift, and contrast boost)
    ctx.filter = `invert(${invertPercent}%) hue-rotate(${hueRotateDeg}deg) saturate(${saturatePercent}%) contrast(${contrastPercent}%)`;
    
    const halfWidth = width / 2;
    const halfHeight = height / 2;

    // A common staple of this YTP meme is mirroring the footage. Apply based on selected mode.
    if (mirrorMode === "left") {
        // Draw the left half normally
        ctx.drawImage(originalImg, 0, 0, halfWidth, height, 0, 0, halfWidth, height);
        // Mirror the left half onto the right side
        ctx.save();
        ctx.translate(width, 0);
        ctx.scale(-1, 1);
        ctx.drawImage(originalImg, 0, 0, halfWidth, height, 0, 0, halfWidth, height);
        ctx.restore();
    } 
    else if (mirrorMode === "right") {
        // Draw the right half normally
        ctx.drawImage(originalImg, halfWidth, 0, halfWidth, height, halfWidth, 0, halfWidth, height);
        // Mirror the right half onto the left side
        ctx.save();
        ctx.translate(width, 0);
        ctx.scale(-1, 1);
        ctx.drawImage(originalImg, halfWidth, 0, halfWidth, height, halfWidth, 0, halfWidth, height);
        ctx.restore();
    }
    else if (mirrorMode === "top") {
        // Draw the top half normally
        ctx.drawImage(originalImg, 0, 0, width, halfHeight, 0, 0, width, halfHeight);
        // Mirror the top half down
        ctx.save();
        ctx.translate(0, height);
        ctx.scale(1, -1);
        ctx.drawImage(originalImg, 0, 0, width, halfHeight, 0, 0, width, halfHeight);
        ctx.restore();
    }
    else if (mirrorMode === "bottom") {
        // Draw the bottom half normally
        ctx.drawImage(originalImg, 0, halfHeight, width, halfHeight, 0, halfHeight, width, halfHeight);
        // Mirror the bottom half up
        ctx.save();
        ctx.translate(0, height);
        ctx.scale(1, -1);
        ctx.drawImage(originalImg, 0, halfHeight, width, halfHeight, 0, halfHeight, width, halfHeight);
        ctx.restore();
    } 
    else {
        // By default ("none"), just draw the full filtered image
        ctx.drawImage(originalImg, 0, 0, width, height);
    }

    return canvas;
}