Schematic of the algorithm. Left panels: Representation of the original data showing the wavelength-dependent spatial shift. The line center location is shown by the green star in the middle row. Middle panels: Representation of the data after the shift (or skew) is removed, showing that a leftover spatial shift is present – the line center position has moved compared to the input. Right panels: After line fitting, the deskewing moves the position of the fit parameter images back to the original line center position.