LABELING METHODS AND APPARATUS USING ENERGY OF TWO WAVELENGTHS

摘要

A method is provided for measuring a relative darkness of an image recorded on a recording medium (106), comprising: applying first electromagnetic energy (132) having a first wavelength to the recording medium (106) to record an image thereon, applying second electromagnetic energy (152) having a second wavelength different from the first wavelength to the recorded image on the recording medium (132), and measuring a reflection (153) of the second electromagnetic energy (152) from the recorded image to determine the relative darkness of the recorded image. Apparatus is provided for measuring a relative darkness of an image recorded on a recording medium 106, comprising: (a) first means 130, 134 for applying first electromagnetic energy 132 having a first wavelength to the recording medium 106 to record an image thereon, (b) second means 150, 154 for applying second electromagnetic energy 152 having a second wavelength different from the first wavelength to the recorded image on the recording medium 106, and (c) measuring means 140, 156 for measuring a reflection 153 of the second electromagnetic energy 152 from the recorded image to determine the relative darkness of the recorded image.