Merging multi-exposure image stacks into a high dynamic range (HDR) image
requires knowledge of accurate exposure times. When exposure times are
inaccurate, for example, when they are extracted from a camera's EXIF metadata,
the reconstructed HDR images reveal banding artifacts at smooth gradients. To
remedy this, we propose to estimate exposure ratios directly from the input
images. We derive the exposure time estimation as an optimization problem, in
which pixels are selected from pairs of exposures to minimize estimation error
caused by camera noise. When pixel values are represented in the logarithmic
domain, the problem can be solved efficiently using a linear solver. We
demonstrate that the estimation can be easily made robust to pixel misalignment
caused by camera or object motion by collecting pixels from multiple spatial
tiles. The proposed automatic exposure estimation and alignment eliminates
banding artifacts in popular datasets and is essential for applications that
require physically accurate reconstructions, such as measuring the modulation
transfer function of a display. The code for the method is available.

将多曝光图像堆叠合并为高动态范围（HDR）图像需要准确的曝光时间，为了解决从相机的 EXIF 元数据提取的曝光时间不准确导致的条纹伪影问题，我们提出直接从输入图像中估计曝光比率的方法，并通过线性求解器高效地解决了该问题，同时该方法还可以在多个空间块中收集像素以消除由相机或物体运动引起的像素错位问题，该自动曝光估计与对齐方法消除了流行数据集中的条纹伪影，对于需要物理上准确重建的应用非常关键，如测量显示器的调制传递函数。该方法的代码可用。