An illumination head (1) for machine vision has an annular support (2) with first, second, third, and fourth illumination sections (3, 4, 5, and 6). The third section (5) has three sets of LEDs (12, 13, 14) arranged in a pattern so that each set illuminates at approximately the same angle. Each set is driven in succession so that a series of three monochrome images at the same angle are captured. These are superimposed by an image processor to provide a color image, although the camera is monochrome. More information can be obtained in such a color image and the high resolution and robustness of monochrome cameras is availed of.