The image-scaling operation is one of the most commonly used video and imaging processing functions. The resizer hardware module in the DaVinci video processing subsystem (VPSS) provides scaling capability in hardware, thus off-loading the system for other processing tasks. To achieve high video quality while maintaining strong overall system performance, a better understanding of the hardware and the algorithm behind it is necessary.

This application report is intended to better acquaint developers with the resizer. Several commonly used image-scaling algorithms are compared and an overview of the resizer hardware is given. Several aspects of the resizer programming are discussed in detail as well, including constant input output sizing, calculation of filter coefficients, and register programming pitfalls. The Linux driver for the resizer is then described, followed by several examples of its use.