On the definition, utility, and practical implementation of X-ray omnidirectional differential phase contrast and dark-field imaging

The paper by Wang and Sawhney (1) describes the use of a speckle pattern in order to retrieve omnidirectional differential phase and dark-field images. Although the approach is methodologically correct and the claim that a simple modulator can have distinct benefits comparted to X-ray optics is true, there are a few passages in both the significance statement and the main text that we find to be inaccurate.