1. A method for determining a quality measure for a video image, comprising: selecting a first encoding unit of the video image as a measuring point; determining a context area of the selected first encoding unit, the context area comprising said selected first encoding unit and at least portions of a plurality of second encoding units that are directly adjacent to the selected first encoding unit; calculating a variance of pixel values in the context area; calculating a variance of pixel values in the selected first encoding unit; calculating a relation between the variance of pixel values in the selected first encoding unit and the variance of pixel values in the context area; and averaging for a plurality of selected first encoding units said relations, wherein the quality measure for the video image is obtained responsive to the averaged relations, wherein the first encoding unit is selected from a relevant area within the video image, the relevant area comprising all encoding units of the video image except those on the edge of the video image or those whose context block has a variance σ 2 cb outside a range (α,β) between α=2 and β=2000.