Quantization Techniques

Quantization is the process of projecting input values with a large set onto output values with a smaller set, where a typical example is the analog-to-digital conversion. It maps the processed data range from large to small to reduce the data amount. In lossy compression, quantization is the main stage which results in losses of information. Specific to the field of point cloud compression, quantization includes geometry and attribute quantization. Geometry quantization maps the coordinates of points to a smaller range to facilitate encoding. Attribute quantization mainly maps the prediction residual or the transformed coefficient of the residual to a smaller range. On the decoding side, the data is reconstructed by inverse quantization, which is approximate to the original data.