Patent ID: 7197980

Claim:
A method of engraving an engraving sheet with an engraving device in accordance with a picture signal, with the engraving sheet formed of a support layer and a whitened engraving layer arranged on the support layer with the engraving layer to be engraved down to the support layer, wherein the support layer is fabricated of biaxially oriented high-density polypropylene, the whitened engraving layer has an opacity of 40% or more, and the support layer is lower in opacity than the whitened engraving layer with a difference of 20% or more between the opacity of the support layer and the opacity of the whitened engraving layer, the method comprising the steps of: generating a picture signal in which a color signal of the whitened engraving layer becomes relatively lower in level when an original picture of a photograph of a face is picked up with an image pickup device; and producing an engraved picture to present a positive image under the presence of reflected light rays and a negative water-mark image under the presence of transmitted light rays entering from behind by allowing the engraving device to engrave the whitened engraving sheet down to the support layer in response to the picture signal depending on the magnitude of the picture signal.