Depth from focus (DFF) is one of the classical ill-posed inverse problems in
computer vision. Most approaches recover the depth at each pixel based on the
focal setting which exhibits maximal sharpness. Yet, it is not obvious how to
reliably estimate the sharpness level, particularly in low-textured areas. In
this paper, we propose `Deep Depth From Focus (DDFF)' as the first end-to-end
learning approach to this problem. One of the main challenges we face is the
hunger for data of deep neural networks. In order to obtain a significant
amount of focal stacks with corresponding groundtruth depth, we propose to
leverage a light-field camera with a co-calibrated RGB-D sensor. This allows us
to digitally create focal stacks of varying sizes. Compared to existing
benchmarks our dataset is 25 times larger, enabling the use of machine learning
for this inverse problem. We compare our results with state-of-the-art DFF
methods and we also analyze the effect of several key deep architectural
components. These experiments show that our proposed method `DDFFNet' achieves
state-of-the-art performance in all scenes, reducing depth error by more than
75% compared to the classical DFF methods.

本文提出了一种端到端的学习方法，称为 “Deep Depth From Focus (DDFF)”，该方法基于深度神经网络，利用配备了 co - 校准的 RGB-D 传感器的光场相机进行数据采集，数据集比既有基准数据集大 25 倍，可以用于解决计算机视觉中的 “Depth from focus (DFF)” 逆问题，实验结果表明，所提出的方法 “DDFFNet” 在所有场景中都取得了最先进的性能。