Herein is disclosed a method for ink or coating density compensation by means of applying calculated additional ink/coating to the pre-decorated substrate or film, and by additionally, if needed, apply colour-correction to pre-decoration print files to compensate for higher-than-desired ink density colour shifts. The method includes the steps of providing a flat polymer web having a uniform grid pattern of grid markers printed thereon, and then thermally transforming the web to form a three-dimensional target grid. The target grid is then digitized and the change in the spacing of the grid markers is measured and recorded. The recorded transformed spacing for each grid marker is then used to modify the initial graphics file to compensate for ink-density irregularities resulting from the shrinking and stretching deformations of the substrate during thermal transformation.