1. A method comprising: capturing an image with a flash; forming at least one weighted masked area of the image by masking at least one central area of the image with a weighting mask; masking at least one further area of pixels of the image by weighting the at least one further area with a further weighting mask to form a further weighted masked area; determining an average brightness measure and an average maximum pixel colour component value for the at least one weighted masked area; determining an average brightness value and an average maximum pixel colour component value for the at least one further weighted masked area; and determining an impact metric indicating the combined impact of the brightness and pixel colour components for the at least one weighted masked area by combining the average brightness measure and average maximum pixel colour component value relating to the weighted masked area and combining the average brightness measure and average maximum pixel colour component value relating to the at least one further weighted masked area.