autocolor (photoshop) inspired algorithm

autocolor_ps.py

def improved_auto_color(image: Image.Image) -> Image.Image:
    """
    Improved version of Photoshop-like Auto Color.
    It works by:
    1. Converting to float and normalizing.
    2. Computing per-channel percentiles (e.g., 0.5% and 99.5%).
    3. Stretching values between those percentiles to [0, 255].
    4. This avoids over-amplifying noise or outliers.
    """
    img_array = np.array(image).astype(np.float32)

    # Process each channel independently
    for channel in range(3):
        channel_data = img_array[..., channel]
        low_percentile = np.percentile(channel_data, 0.5)
        high_percentile = np.percentile(channel_data, 99.5)

        if high_percentile > low_percentile:
            # Stretch values between low and high percentiles to [0, 255]
            stretched = (channel_data - low_percentile) * 255.0 / (high_percentile - low_percentile)
            img_array[..., channel] = np.clip(stretched, 0, 255)

    return Image.fromarray(img_array.astype(np.uint8))