public static int getImageType(BufferedImage img) {
    int imageType = img.getType();
    switch (imageType) {
        case BufferedImage.TYPE_CUSTOM: // If the source image type is not set...
            imageType = img.getAlphaRaster() != null ? BufferedImage.TYPE_INT_ARGB_PRE : BufferedImage.TYPE_INT_RGB;
            break;
        // Handle both TYPE_BYTE_BINARY (1-4 bit/pixel) and TYPE_BYTE_INDEXED (8 bit/pixel).
        case BufferedImage.TYPE_BYTE_BINARY:
        case BufferedImage.TYPE_BYTE_INDEXED:
            if (img.getColorModel() != null) {
                imageType = img.getColorModel().hasAlpha() ? BufferedImage.TYPE_INT_ARGB_PRE : BufferedImage.TYPE_INT_RGB;
            }
            break;
        default:
            break;
    }
    return imageType;
}