Class DWTUtil

StegaPy/util/dwt_util.py:9–89

离散小波变换工具类

class DWTUtil:
    """离散小波变换工具类"""
    
    @staticmethod
    def forward_dwt(image_data, wavelet='db1', level=3):
        """
        执行正向小波变换
        
        Args:
            image_data: 2D numpy数组，图像数据
            wavelet: 小波基名称，默认'db1'（Daubechies 1）
            level: 分解层数，默认3
        
        Returns:
            小波系数列表，格式为 [cA, (cH, cV, cD), ...]
        """
        coeffs = pywt.wavedec2(image_data, wavelet, level=level)
        return coeffs
    
    @staticmethod
    def inverse_dwt(coeffs, wavelet='db1'):
        """
        执行逆向小波变换
        
        Args:
            coeffs: 小波系数列表
            wavelet: 小波基名称
        
        Returns:
            重构后的图像数据
        """
        return pywt.waverec2(coeffs, wavelet)
    
    @staticmethod
    def get_subbands(coeffs):
        """
        从小波系数中提取子带
        
        Args:
            coeffs: 小波系数列表
        
        Returns:
            子带列表，每个元素为 (level, subband_type, data)
        """
        subbands = []
        cA = coeffs[0]  # 近似系数
        
        for i, (cH, cV, cD) in enumerate(coeffs[1:]):
            level = i + 1
            subbands.append((level, 'H', cH))  # 水平细节
            subbands.append((level, 'V', cV))  # 垂直细节
            subbands.append((level, 'D', cD))  # 对角细节
        
        return subbands
    
    @staticmethod
    def reconstruct_subbands(subbands, original_coeffs, wavelet='db1'):
        """