Method for merging superpixels

The present invention relates to a method of merging superpixels in an image from an initial number of superpixels into a final number of superpixels, the method being performed by a user device (100). The method comprises receiving the image (S100) comprising the initial number of superpixels and the value, K, (S110) of the final number of superpixels into which the image is to be segmented. A similarity value for the similarity between each superpixel and its neighboring superpixels is calculated (S120). The similarity value is based on a Penalized Average Linkage Cuts (PALC) value between each pair of neighboring superpixels. The pair of superpixels that has the highest similarity value is selected (S140) and the selected pair of superpixels is merged (S180). The method is repeated until it is determined (S190) that the current number of superpixels in the image is equal to the received value of the final number of superpixels.