An electronic method for calibrating a display unit using a multicolour colourimetrically calibrated camera having a plurality of separate image sensors configured to separately capture red, green, and blue light, the method comprising: displaying (310, 320) a plurality of pattern images on the display unit, wherein displaying the plurality of pattern images comprises displaying separate red, green and blue test pattern images followed by displaying a multicolour calibration pattern image; capturing (315, 325) the plurality of pattern images displayed on the display unit with the camera; comparing RGB values extracted from captured images of the separate red, green and blue test pattern images with the separate red, green and blue test pattern images and calculating XYZ coordinates of the colors of the separate red, green and blue test pattern images in order to compensate for luma and chroma spatial non-uniformity of the display unit so as to obtain three image maps; transferring RGB values of each pixel of the captured image of the multicolor calibration pattern image to XYZ coordinates, wherein the XYZ coordinates are compensated for luma and chroma spatial non-uniformity by applying the three image maps to the captured image of the multicolor calibration pattern image in order to transfer RGB values for each pixel in the image captured by the camera to absolute XYZ coordinate based on the calculated XYZ coordinates of the colors of the separate red, green and blue test pattern images; comparing a set of reference absolute XYZ coordinates of a set of colours from the multicolour calibration pattern image with the XYZ coordinates obtained from the captured image of the multicolour calibration pattern image; and calibrating the display unit based on the comparison between the reference XYZ coordinates and the XYZ coordinates obtained from the captured image of the multicolour calibration pattern image. displaying (310, 320) a plurality of pattern images on the display unit, wherein displaying the plurality of pattern images comprises displaying separate red, green and blue test pattern images followed by displaying a multicolour calibration pattern image; capturing (315, 325) the plurality of pattern images displayed on the display unit with the camera; comparing RGB values extracted from captured images of the separate red, green and blue test pattern images with the separate red, green and blue test pattern images and calculating XYZ coordinates of the colors of the separate red, green and blue test pattern images in order to compensate for luma and chroma spatial non-uniformity of the display unit so as to obtain three image maps; transferring RGB values of each pixel of the captured image of the multicolor calibration pattern image to XYZ coordinates, wherein the XYZ coordinates are compensated for luma and chroma spatial non-uniformity by applying the three image maps to the captured image of the multicolor calibration pattern image in order to transfer RGB values for each pixel in the image captured by the camera to absolute XYZ coordinate based on the calculated XYZ coordinates of the colors of the separate red, green and blue test pattern images; comparing a set of reference absolute XYZ coordinates of a set of colours from the multicolour calibration pattern image with the XYZ coordinates obtained from the captured image of the multicolour calibration pattern image; and calibrating the display unit based on the comparison between the reference XYZ coordinates and the XYZ coordinates obtained from the captured image of the multicolour calibration pattern image.