High dynamic range (HDR) images have many practical applications because they offer an extended dynamic range and a more realistic visual experience. A HDR image is usually stored in floating-point format, so pre-processing is required to make the HDR image compatible with coding standards. A transfer function is also used to achieve better coding efficiency. Typically, HDR images are generated using several low dynamic range (LDR) images with different exposures. Instead of compressing the HDR image when it is generated from images with multiple exposures, this study proposes a technique to compress the multi-exposure images. The HDR image generation, as well as the multi-exposure images fusion, can be realized in the decoder. The proposed framework encodes the multi-exposure images using MV-HEVC where the inter-view redundancy is well exploited when an accurate intensity-mapping function between the multi-exposure images has been established. Multi-exposure image coding is used to produce a high-quality HDR image so the rate–distortion optimization (RDO) is modified by considering both the reconstruction quality of the current block and its effect on the multi-exposure fused image. A Lagrange multiplier is modified to maintain a balance between the rate and the modified distortion during the RDO process. Compared to encoding the generated HDR image using HEVC range extension, the experimental results show that the proposed technique achieves significant bitrate savings for equivalent quality in terms of HDR-VDP-2.

高动态范围（HDR）图像具有许多实际应用，因为它们提供了更大的动态范围和更逼真的视觉体验。HDR图像通常以浮点格式存储，因此需要进行预处理以使HDR图像与编码标准兼容。传递函数也用于获得更好的编码效率。通常，HDR图像是使用具有不同曝光量的几个低动态范围（LDR）图像生成的。这项研究提出了一种压缩多曝光图像的技术，而不是压缩从多次曝光的图像生成的HDR图像。可以在解码器中实现HDR图像生成以及多重曝光图像融合。所提出的框架使用MV-HEVC对多曝光图像进行编码，当在多曝光图像之间建立了精确的强度映射功能时，可以很好地利用视图间冗余。多曝光图像编码用于生成高质量的HDR图像，因此应通过考虑当前块的重建质量及其对多曝光融合图像的影响来修改速率失真优化（RDO）。修改了拉格朗日乘数，以在RDO过程中保持速率与修改后的失真之间的平衡。与使用HEVC范围扩展对生成的HDR图像进行编码相比，实验结果表明，针对HDR-VDP-2的同等质量，所提出的技术可节省大量比特率。