There is provided an apparatus (100) comprising one or more processors (102) configured to acquire a multi-/hyperspectral two-dimensional image of an object at respective wavelengths. For at least one pixel of the image corresponding to a first point on an object surface, a set of intensity values for said at least one pixel is compared to a characteristic curve to determine a similarity measure. A first angle of the first point is estimated from the similarity measure or a correction is applied to the image at the first point using the similarity measure. The characteristic curve is a difference between a spectrum of at least one second point on the object surface at a second angle with respect to a plane of the image and a spectrum of at least one third point on the object surface at a third angle with respect to the plane of the image.