1. Process for use in a device for detecting faces in an image, the image being composed of a plurality of pixels, comprising the steps of: using a processor, to perform the steps of: detecting the flesh coloured pixels in the image, segmenting the image into regions of homogeneous colour, selecting, among the regions of homogeneous colour, of the regions comprising a number of flesh coloured pixels greater than a first predetermined threshold, the regions selected being said to be flesh coloured regions, merging of the neighbouring flesh coloured regions until the merge cost attains a second predetermined threshold, the merge cost linearly weighting a merge cost relating to the shape of the regions and a merge cost relating to the colour of the regions, and excluding false positives, wherein the merge step comprises the substeps of calculating the merge cost relating to the colour of the regions by calculating the mean difference in colour between neighbouring regions, and calculating the merge cost relating to the shape by calculating the overlap between the area of the region and the area of an ellipse having the same centre of gravity as the said region and overlapping it best, the elliptic nature of each region by calculation of the ratio of the sum of the number of pixels of the region outside the ellipse and of the number of pixels of the ellipse outside the region to the number of pixels of the ellipse, and the difference between the minimum of the measures of elliptic nature of the two neighbouring regions and the measure of elliptic nature of the merged region.