Method and image capturing apparatus for minimising error in ambient light corrected images

Abstract

According to an aspect, there is provided a method for minimising error in ambient light corrected image due to motion, the method comprising: capturing a plurality of primary images with controlled intensity of illumination varying over time, estimating an error value due to motion for each of a plurality of sub-sets of the plurality of primary images, and performing ambient light correction on an error minimised sub-set of primary images having the lowest estimated error value to generate an ambient light corrected (ALC) image with a minimised error. Estimating the error value for each sub-set of the plurality of primary images comprises identifying a pair of primary images in the sub-set including a first primary image and a second primary image, wherein the first primary image is captured temporally before the second primary image, determining a displacement vector matrix between the pair of primary images, and estimating the error value for the sub-set of primary images based on the displacement vector matrix between the pair of primary images. Determining the displacement vector matrix includes dividing the first primary image into a plurality of first grid elements and dividing the second primary image into a plurality of second grid elements, matching first grid elements to second grid elements which correspond to the same position on the object, and determining a displacement vector between each matched first grid element and second grid element to determine a displacement vector matrix describing the displacement vector of each grid element.