A method of reducing artifacts in an image previously processed by block transform encoding may comprise the steps of:

• determining block boundaries;
• determining an approximate metric of artifact visibility;
• optionally interpolating across block boundaries;
• adaptively filtering luminance;
• optionally adaptively filtering chrominance;
• adaptively adjusting local saturation variation; and
• adaptively simulating high spatial frequency image detail;

  wherein the adaptive steps are executed to an extent or in an amount depending on the metric or standard or measurement of artifact visibility.