Thin horizontal lines and edges are vulnerable to flickering on an interlaced monitor. To reduce flickering filtering is adaptively applied to the pixels of lines or edges to reduce the flicker energy or contrast of the pixel to a level less than a threshold energy or contrast necessary for flickering under the local conditions. The flicker energy or contrast is a function of the luminance of the line pixel and vertically adjacent background pixels, the number of intensity transitions in the vertical vicinity of the line, and the line length. Adaptive filtering by the described method is computationally conservative and does not adversely effect the detail in the remainder of the image.