Movie Studio Of The Year Photo Remover

function processImage(originalImg, keyColor = '#00FF00', tolerance = 100, softness = 40) {
    // Create a canvas to process the image
    const canvas = document.createElement('canvas');
    canvas.width = originalImg.width;
    canvas.height = originalImg.height;
    const ctx = canvas.getContext('2d', { willReadFrequently: true });
    
    // Draw the original image onto the canvas
    ctx.drawImage(originalImg, 0, 0);

    // Get the image data for pixel-level manipulation
    const imgData = ctx.getImageData(0, 0, canvas.width, canvas.height);
    const data = imgData.data;

    // Use a temporary canvas to resolve the target CSS keyColor to exactly extraction-ready RGB values 
    const tempCanvas = document.createElement('canvas');
    tempCanvas.width = 1;
    tempCanvas.height = 1;
    const tempCtx = tempCanvas.getContext('2d', { willReadFrequently: true });
    tempCtx.fillStyle = keyColor;
    tempCtx.fillRect(0, 0, 1, 1);
    
    // Deconstruct RGB
    const [rKey, gKey, bKey] = tempCtx.getImageData(0, 0, 1, 1).data;

    // Parse numeric limits to handle input robustness
    const tol = Number(tolerance);
    const soft = Number(softness);

    // Iterate through every pixel for "Movie Studio" Chroma Key (Greenscreen) Removal
    for (let i = 0; i < data.length; i += 4) {
        const r = data[i];
        const g = data[i + 1];
        const b = data[i + 2];
        const a = data[i + 3];

        // Skip fully transparent pixels
        if (a === 0) continue;

        // Calculate Euclidean distance mapped in 3D RGB color space
        const distance = Math.sqrt(
            Math.pow(r - rKey, 2) +
            Math.pow(g - gKey, 2) +
            Math.pow(b - bKey, 2)
        );

        // Subtractive color mixing logic
        if (distance < tol) {
            if (distance < tol - soft) {
                // If it squarely falls within the strict tolerance - remove background entirely
                data[i + 3] = 0;
            } else {
                // Anti-aliasing soft edges: transition nicely out of transparency
                // to avoid jagged borders commonly seen in harsh background removers
                const alphaRatio = (distance - (tol - soft)) / soft;
                data[i + 3] = Math.floor(a * alphaRatio);
            }
            
            // Optionally, we can also perform spill suppression on remaining semi-transparent edge pixels 
            // by draining out matching component chroma, but fading transparency suffices mostly.
        }
    }

    // Put the modified image data back
    ctx.putImageData(imgData, 0, 0);
    
    return canvas;
}