A method of forming an image of an object, the method comprising - acquiring (21, 22) a series of source images of the object, the series comprising at least three source images of the object at temporally distributed time points; - generating a composite color image from the series of source images; - selecting a color pixel value for each particular pixel position in the composite image dependent on pixel values of the source images at positions that correspond to the particular pixel position; - displaying the composite image with pixels having pixel color values determined according to the preceding steps; characterized by - determining an amount of spread in the pixel values in the source images at the position that corresponds to the particular pixel position, and displaying a grey value at the particular pixel position when the amount of spread is zero and a color pixel with increased color saturation when the particular pixel position has an increased amount of spread; - computing information about a time point of a transition in the pixel values for the particular pixel position in the source images and controlling the hue of the color of the color pixel value dependent on said information about the time point; - determining, for the particular pixel position in the composite image, a value that is indicative of an extreme among the pixel values in the source images at positions that correspond to the particular pixel position; - controlling brightness of the color pixel value for the particular pixel position dependent on the value that is indicative of the extreme. - acquiring (21, 22) a series of source images of the object, the series comprising at least three source images of the object at temporally distributed time points; - generating a composite color image from the series of source images; - selecting a color pixel value for each particular pixel position in the composite image dependent on pixel values of the source images at positions that correspond to the particular pixel position; - displaying the composite image with pixels having pixel color values determined according to the preceding steps; - determining an amount of spread in the pixel values in the source images at the position that corresponds to the particular pixel position, and displaying a grey value at the particular pixel position when the amount of spread is zero and a color pixel with increased color saturation when the particular pixel position has an increased amount of spread; - computing information about a time point of a transition in the pixel values for the particular pixel position in the source images and controlling the hue of the color of the color pixel value dependent on said information about the time point; - determining, for the particular pixel position in the composite image, a value that is indicative of an extreme among the pixel values in the source images at positions that correspond to the particular pixel position; - controlling brightness of the color pixel value for the particular pixel position dependent on the value that is indicative of the extreme. - determining, for the particular pixel position in the composite image, a value that is indicative of an extreme among the pixel values in the source images at positions that correspond to the particular pixel position; - controlling brightness of the color pixel value for the particular pixel position dependent on the value that is indicative of the extreme.