A printed substrate may include a substrate that may be a paper or a thermoplastic foil. At least one digitally printed decor and at least one patch may be provided on the substrate. The at least one patch may include at least one color reference area having at least one digital ink. The patch may be located on a part of the substrate that is substantially free of the at least one printed decor.

A method to produce a building panel, including: providing a substrate, applying a thermosetting binder in dry form on the substrate for forming a sub-layer, applying a sheet on the sub-layer, and pressing the substrate, the sub-layer and the sheet together to form a building panel, thereby the thermosetting binder of the sub-layer impregnates the sheet from below. Also, a semi-finished product.

A method to produce a building panel, including: providing a substrate, applying a thermosetting binder in dry form on the substrate for forming a sub-layer, applying a sheet on the sub-layer, and pressing the substrate, the sub-layer and the sheet together to form a building panel, thereby the thermosetting binder of the sub-layer impregnates the sheet from below. Also, a semi-finished product.

A method for formulating an ink for a gravure printing press may involve digitally printing of a decor and a patch onto a substrate. The patch may include at least one color reference area. The color reference area may include at least one digital ink. The patch may be located on a part of the substrate that is substantially free of the dcor. A color of the at least one color reference area may be measured. A tone of an ink for gravure printing may be adjusted to match the color of the at least one color reference area.