derotated

Derotated describes something that has been rotated back to a standard orientation. In practice, derotation is a preprocessing or correction step used to remove or compensate for rotation that occurred during capture, processing, or data acquisition. The result is an image, volume, or coordinate system aligned with a predefined reference orientation.

In computer vision and image processing, derotation aligns images so that features correspond across images. This facilitates tasks such as image registration, feature matching, stitching, and object recognition. Derotation can be performed by estimating a rotation angle using feature correspondences, line or edge detection, or learning-based approaches, then applying an inverse rotation to the image. Interpolation during rotation can introduce artifacts, so methods balance accuracy and quality.

In astronomy and optics, field derotation compensates for apparent rotation of the field of view caused by telescope motion or instrument geometry. Derotators are mechanical or optical devices that preserve a fixed orientation of the image or detector while the sky moves.

In medical imaging, derotation is used to standardize orientation across slices or modalities, enabling consistent 3D reconstruction and comparison between studies. In tomography and electron microscopy, derotation can refer to aligning projections or micrographs to a common orientation before reconstruction.

Limitations include estimation errors, interpolation artifacts, and potential distortion if the rotation is not rigid or if geometric operations are applied inconsistently. The term is widely used as an adjective (derotated) and as a process (derotation).