再抽样后，调制前，信后总要先被量化。这里提供一段程序用于解决这一问题。-after sampling, we always need to quantize the signal in order to do the modulation. here i provide a segment of code which can solve this problem

量化算法是数字水印技术嵌入算法的重要组成部分。通过修改数字图像的低频系数将所需嵌入的水印信息嵌入到载体图像中-Quantization Watermarking embedding algorithm is an important part. Digital image by modifying the frequency coefficients will be required to embed the watermark information is embedded into the

图像的差值脉冲编码调制，通过预测器中现有系数进行预测，并统计预测误差，再用量化器进行量化-Differential pulse code modulation of the image, through the existing coefficient in the predictor to predict, and statistical prediction error and quantize

灰度图像的量化和直方图均衡化直接调用函数。量化是指将像素灰度转换成离散的整数值的过程。量化等级越多，所得图像层次越丰富，灰度分辨率高，图像质量好，但数据量大。-Write MATLAB functions to quantize grayscale image with given quantization step Q. Process the given test images “Lena” with quantization steps Q=2, 4, 8 16, 32, 64, 1