Implementation of HDR Photographic Pipeline in Mobile Devices

摘要

The high dynamic range (HDR) photography offers significantly better quality than conventional digital images stored in low dynamic range (LDR) formats. We replace the standard image capture pipeline in mobile phones with an HDR acquisition pipeline based on the multi-exposure method. We discuss limitations of the mobile platforms that affect architecture of the proposed pipeline, then implementation of the pipeline on a smartphone with ARMv6 processor (Nokia N8) is described. We report timings for fundamental HDR algorithms and discuss programming techniques that speed-up execution and reduce RAM memory usage. The results compare favourably to proprietary iPhone 4 HDR implementation and show that the HDR pipeline can be efficiently implemented on existing camera phones using high-level APIs and no dedicated hardware.