texture forms photographs etc in the event of several reference images being taken under various shot conditions for a given hairstyle type the metadata of the various reference images will moreover be able to comprise one or more conversion matrices linked to each of the shot parameters and allowing conversion of the colorimetric values of each of the pixels of the reference image on the basis of those of each of the pixels of the image defined as principal reference image thus by way of example in the example from fig1 the images cha 0 form a set of reference images taken with various shot conditions for the person 100 a having the hairstyle type a and the images chb 0 form a set of reference images taken with various shot conditions for the person 100 e having the hairstyle type b among these images an image will be defined for each hairstyle type a or b which will form a principal reference image for the hairstyle type under consideration this step will be able to be reproduced for a number n of hairstyle types in a step s 12 high resolution digital images of persons 111 a 112 a 113 a 114 a etc having a hairstyle in a given hairstyle type for example a with hair of different type for example various natural colors are produced this step is reproduced for each of the hairstyle types for each hairstyle type it will be possible to record m images that each correspond to a color for example of the order of ten or so or one hundred or so natural colors according to the desired objective in the exemplary embodiment in question which are respectively indicated cha 1.